IGS Winter Issue 2017 by IGS Magazine

INTELLIGENT GLASS SOLUTIONS Winter 2017

www.igsmag.com

Meet James O’Callaghan Multiple Industry Award Winner

Elke Harreiss Discusses FENSTERBAU FRONTALE’S 30 year milestone

pages of choice GPD papers

The Glass Supper 2017 – Let’s talk!! Inside Apple HQ, Photo courtesy of Foster + Partners • Copyright Nigel Young

Proven performance. Accelerated innovation.

ENABLING

VISIONARY DESIGN 50+ years of proven performance and continuing advances Decades after Dow Corning helped pioneer the four-sided silicone structural glazing technology that opened architects’ eyes to a new era of design, hijY^Zh XdcÑ gb djg higjXijgVa h^a^XdcZ hZVaVcih ]VkZ an expected service life of at least 50 years. Emphasizing silicone’s high performance, these sealants – and our full line of proven highperformance building products – will soon be available as DOWSIL™ brand, with the same trusted silicone chemistries, features and product WZcZÑ ih ndjÈkZ XdbZ id ZmeZXi [gdb Dow Corning® brand products.

Imagine a future that’s possible with long-service-life sealants. www.dowcorning.com/50plus ®™

IgVYZbVg` d[ I]Z 9dl 8]Zb^XVa 8dbeVcn Å9dlÆ dg Vc V[Ñ a^ViZY XdbeVcn d[ 9dl# The Corning portion of the Dow Corning trademark is a trademark of Corning Incorporated, used under license. © 2017 The Dow Chemical Company. All rights reserved. AGP15298. dow_42218047915.

FOREWORD

Its nice to come “Home” In June 2017 we celebrated the 25th anniversary of GPD in Finland where, arguably, one of the worlds most respected and best attended glass industry conferences underwent a facial. The venue changed from Tampere Talo where it had been since before Jesus turned water into wine, to the Tahti Arena, allowing for the first time an open plan setting with all presentations in the same hall, plus the space was shared with exhibitors. 24 hours before the show got underway anxious delegates were discussing amongst themselves if the speakers were too close to the exhibitors and therefore be a disturbing factor to one or the other, however once the event began those fears disappeared and the majority of delegates were happy. Here, on the occasion of the 25th anniversary of the event, the Chairman of the Organising Committee Jorma Vitkala was given a 2 minute standing ovation and presented with an award for his significant contribution to the glass industry. The Jorma Vitkala Award of Merit was born. In future the award will recognise one individual who has made a major contribution to the sustainable development of the industry. Huge congratulations also to James O’Callaghan who was named “Glass Person of the Year” and the recipient of the much coveted Phoenix Award. James was the first Brit to receive this international award for 36 years, since Sir Alistair Pilkington was presented as the award winner back in 1981. 2017 was a fantastic year for both Jorma & James, very well done to both these gentlemen whose stars have risen and their status as global game changers is unable to be challenged or denied. And whilst on the subject of change, the eagle-eyed among you would have noticed that similar to GPD, your favourite industry publication has itself undergone a fair amount of plastic surgery. There’s a fresh new look to IGS, a new logo, and new style layout inside the magazine. The ethics, principles, focus and excellence of the magazine remain unchanged and unchallenged, not just as a glass industry magazine, but as the best of its kind in the world. They say the best fruit is out on a limb, we’re going out on that precarious limb fearlessly determined to bring you the best fruit. To complement the fresh new look of IGS magazine we have also created a website. Yes you happy good looking people, you have been blessed by the Good Lord Himself because he made all IGS readers in his own image, after 14 years we have now created www. igsmag. com. This website has been created with you in mind, it’s the place that the architectural glass industry can call “Home”. Excuse the well used cliche but as much as possible igsmag. com is designed to be your ultimate one stop shop for information on global architectural glass technology. We have a dedicated Marketing Director in Lewis Wilson who will update your material onto our website fast, within the hour. Subscribe to igsmag.com and become one of our Private Members, you will find its nice to come home.

Our dedicated Marketing Director, Lewis Wilson

Companies that consistently look to innovate know that the free flow of conversation through friendly discussion invigorates the mind, it is what feeds and waters fresh ideas and innovation. This in turn leads to improvements in products and processes, advancement in systems and technologies and so on. The Glass Supper series of events in London on the first Thursday of December each year facilitates initiatives that foster the free flow of friendly conversation and fruitful discussion, a fundamental cornerstone to the global nature and sustainable growth of the architectural glass economy. The water has been turned into wine, all of us at IGS raise our glass and wish all of you at the Tate Modern and beyond a fruitful Glass Supper, a very merry Christmas and a profitable 2018!

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INTELLIGENT GLASS SOLUTIONS

INSIDE THIS ISSUE James O’Callaghan, Founding Partner, Eckersley O’Callaghan page 4 With rapid societal change, our challenge is how best to shape and transform our built environment so that it is not only ﬁt for purpose in the future but it is the very best that human endeavour can offer.

Ms. Elke Harreiss, Exhibition Director, FENSTERBAU FRONTALE page 11 One of the central focuses this year is on solutions for the automation of windows and facades and this will be presented in a new and very special show

Ms. Stephanie Akkoui-Hughes, Founder & CEO Akka Architects page 20 To be leaders in the mature sense of the word we have to shift from “designing for” to “designing with”. We need to shift our leaders roles from being disctators to being facilitators.

2 | Intelligent Glass Solutions | Winter 2017

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INTELLIGENT GLASS SOLUTIONS

INSIDE THIS ISSUE Dr. Jochen Mignat, Mignat Pr for Josef Gartner GmbH page 29 The new landmark of the Russian Port Metropolis is being built right by the sea and looks like a glass needle that is twisting smoothly upwards into the sky.

Stanley Yee, Dowsil page 34 Evolving code requirements and their interpretation can leave architects scrambling to update construction details while trying to maintain the original design content

Rouven Seidler, Seen GmbH page 38 While the pattern shows only black inside so that the view through the pane is hardly, or not at all disturbed, the outer shell of the building shimmers and shines in a multi-facetted way.

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INTRODUCTION

Why

As I take on the privilege of writing the introduction to IGS ahead of our industryâ&#x20AC;&#x2122;s annual celebration, the Glass Supper, I wonder if it is strange that I wish to reafďŹ rm that we are more relevant than ever. But why preach to the converted? 4 | Intelligent Glass Solutions | Winter 2017

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INTRODUCTION

Matters

James O’Callaghan Founding Partner Eckersley O’Callaghan

The reason is that I truly believe we are at a point in time when society is looking squarely at us to deﬁne tomorrow’s built environment. This year, we have achieved great feats of design and construction; but to remain relevant we must redouble our efforts, collaborate and continue to innovate. The world is changing very quickly, we must keep up, else we may not leave the legacy that our next generation deserves when they take over the reins. The truth is that progress is made incrementally, project by project, and it is a process that does not simply just happen without concerted toil. The other truth is that there is huge potential to be realised for glass, arguably more so than for most other construction materials. We have proven time and time again that joint enterprise between clients,

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designers, makers, and researchers is the key to realising innovation. It is therefore paramount that we accumulate our collective experiences and knowledge, not divide and conquer. Our industry is relatively small, but there are opportunities for us all to succeed. The recently opened Apple Michigan Avenue in Chicago represents a landmark that challenges us to reconsider where the boundary lies between public and private realms. I have engineered many glass structures with Apple, but this is the ﬁrst to offer customers a complete 360 degree view of their surroundings at store level. In collaboration with Foster + Partners, we have created something of an anti-building that lightly choreographs a patch of space, inviting the community to seamlessly ﬂow through. In stimulating regeneration, it’s a powerful piece of architecture. ³

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INTRODUCTION

This blurring between public and private realms is apt and perhaps represents our time. We no longer have a problem with full disclosure, in fact we rather expect it. This is a time when society is characterised by shared ownership and knowledge, working practices deconstructed and reformed, modes of communication freed of traditional constraints. In more than one sense, transparency is a valued commodity. In response, we are now changing the way we design the built environment for society to live, work and play.

The beneﬁts of natural daylighting on human wellbeing are well researched and documented, as is the need for connection with the outdoors

Urbanisation, the relentless population shift from rural to urban areas, is a key theme of our generation. A Megatrend, if you will. Today, more than half of the world’s population lives in towns and cities. It is expected that 70 percent of the world population will be urban by 2050, and that most urban growth will occur in less developed countries. With rapid societal change, our challenge is how best to shape and transform our built environment so that it is not only fit for purpose in the future but it is the very best that human endeavour can offer. Frankly, land and resources are far too finite to settle on the mediocre and for innovation not to happen. Our work in glass may occupy a niche within the construction industry, perhaps sitting at the margins of this greater narrative, but we all understand its impact. The benefits of natural daylighting on human wellbeing are well researched and documented, as is the need for connection with the outdoors (as we spend more time inside) and with each other (as we spend more time at work!). This is the fundamental and unique proposition of glass as a construction material. The i360 in Brighton was the deservedly winner at this year’s Structural Awards – an observation tower elevating the public up to 162m above ground. Make no mistake – the needle is the engineering achievement here, but ultimately it is the enabler for the curved glass enclosure that offers views across the South Coast. The glass provides both connection and haven. The past decade’s dominant line of enquiry for glass has been undoubtedly large format. I recently saw a LinkedIn post showing a lorry ready to transport a 18m long

Internal view of pod. Photo: Kevin Meredith

panel of glass. Wow. We have made signiﬁcant strides in synthesising design and technology to reach this point, and large format glass is now at a maturity where it can be delivered by suppliers from all around the world. In the pursuit of transparency, size certainly mattered but energy now governs, and we must refocus our collective efforts in this direction. With increasingly stringent codes in energy performance, glass will always be the easy target. Unless innovations addressing this issue are realised, we are likely to see smaller windows at work and

We may not control our clients’ purse strings, but we must embrace our role as advocates of the value of progressive design and long-term thinking.

External views of pod. Photos: Paul Raftery

at home. This is not only bad news for the glass industry but completely at odds with the needs of future society. We must fight to keep glass relevant. Designers and engineers have collaborated to create ingenious and resourceful ways of providing solar control through static and mechanical means. The new Bloomberg HQ in London is a fine example that it is possible to create an exceptionally sustainable building with extensive glazing, as is the Apple Park which collates many of the latest advances in the industry. Both projects make use of crafted shading structures that complement rather than detract. Glass technology has also evolved such that large format can be coated, printed, and insulated. In combination, we have been able to incorporate glass into responsible building solutions in even the most challenging of climatic environments. The emerging field of dynamic and responsive glass technologies offers a tantalising alternative by intelligently moderating the energy entering our buildings in the material itself. Such as through electrochromics and liquid crystal. Glass can change its light transmittance

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characteristics and so enter the 4th dimension (controllable by an app?!). If design has challenged technology to innovate in the past, technology must take the lead again and ignite the imaginations of designers to ﬁnd the opportunities that bring their products to market. This model of delivering innovation is a complex process but we have already seen an example of success with Merck and Google’s ambitious headquarters in California where their take on adaptive glass will be reportedly extensively employed. We may not control our clients’ purse strings, but we must embrace our role as advocates of the value of progressive design and long-term thinking. This may feel like a battle that is stacked against us, but there will be small victories along the way and I call for collective resilience and resolve. This is a huge responsibility and we must be accountable as an industry in keeping glass relevant. Transparency matters. It always has. But to keep glass relevant, we have to fully participate in deﬁning our rapidly changing world.

Winter 2017 | Intelligent Glass Solutions | 7

INTELLIGENT GLASS SOLUTIONS

CONTENTS

Introduction

Industry Insight

Stanley Yee, Dowsil Thin proﬁle insulation creates space for design freedom

Rouven Seidler, Seen GmbH All Shiny and new *World Exclusive*

Marcin Brzezicki, Wroclaw University of Science and Technology New trends in the architecture of transparent facades

The Paul Bastianen IGS Column Windows getting smart faster

Paul Bastianen Pt.2 The Glass Supper over 7 years - A never ending story

James O’Callaghan, CEO & Founding Partner Eckersley O’Callaghan

Executive Boardroom Commentary 11.

Elke Harreiss, Exhibition Director FENSTERBAU FRONTALE 2017 A world Class Event in Nuremburg

igsmag.com • Website Introduction 11

15.

Lewis Wilson, Marketing Director igsmag.com Intensiﬁed engagement with the industry - Welcome to our World!

Executive Boardroom Commentary 20 29

Stephanie Akkoui-Hughes, CEO & Founder AKKA Architects People-centric, buildings designed with people in mind

Celebrating 25 years of GPD in Finland 60

Sophie Pennetier, Mark Bowers, Guillaume Evain, ARUP & BIG Architects Shaping ultra-thin glass

Benjamin Beer, Meinhardt Facade Technology Free form shape cold bent structural silicone glazed facades - design concept and challenges

Case Study 29

Dr.Jochen Mignat, Mignat Pr Europe’s tallest skyscraper in St.Petersburg, Lakhta Center

8 | Intelligent Glass Solutions | Winter 2017

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CONTENTS

100 ARUP & BIG Sustainable facade design for glazed buildings in a blast resistant urban environment

ENAR Envolventes Arquitectonicas UPM New concept of horizontal structural elements in glass, self-bearing....shape

Graham Dodd, ARUP Structural glass sandwich panels

102

Fabio Favoinoa, Luigi Giovanninic, Roel Loonend Smart glazing in intelligent buildings, what can we stimulate?

Miguel Angel Ruiz, Pedro Rodriguez, Martifer Metallic Constructions Transparent Collaboration, Banco Popular HQ - Auditorium, Madrid Spain

105

Sandro Casaccio, Kuraray Europe GmbH Exciting architectural case studies from all around the world

Viviana Nardini, Florian Doebbel, SIKA Services AG Structural silicone joints in cold bent SSG units

112 AUTHORS DETAILS

Front Cover Photo: Inside Apple HQ, Photo courtesy of Foster + Partners Copyright Nigel Young INTELLIGENT GLASS SOLUTIONS Winter 2017

www.igsmag.com

Intelligent Glass Solutions is Published by Intelligent Publications Limited (IPL) ISSN: 1742-2396

Meet James O’Callaghan

Publisher: NIck Beaumont

Multiple Industry Award Winner

Elke Harreiss Discusses FENSTERBAU FRONTALE’S 30 year milestone

INTELLIGENT GLASS SOLUTIONS

pages of choice papers 50 GPD

The Glass Supper 2017 – Let’s talk!! Inside Apple HQ, Photo courtesy of Foster + Partners • Copyright Nigel Young

Accounts: Richard Marks Editor: Sean Peters Production Manager: Kath James

100

102

Director of International Business Network Development: Roland Philip Manager of International Business Network Development: Maria Jasiewicz Marketing Director: Lewis Wilson Design Director: Antony Parselle Page Design Advisor: Arima Regis Design and Layout in the UK by: aparselledesign Tel: +44 (0) 1727 811842

Intelligent Glass Solutions is a quarterly publication. The annual subscription rates are £79 (UK) , £89 (Ireland & Mainland Europe), & £99 (Rest of the World) Email: nick@intelligentpublications.com Published by: Intelligent Publications Limited 3rd Floor, Omnibus House, 39-41 North Road, London N7 9DP, United Kingdom Tel: +44 (0) 7703 487744 Email: nick@intelligentpublications.com www.igsmag.com

The entire content of this publication is protected by copyright. All rights reserved. None of the content in this publication can be reproduced, stored or transmitted in any form, without permission, in writing, from the copyright owner. Every effort has been made to ensure the accuracy of the information in this publication, however the publisher does not accept any liability for ommissions or inaccuracies. Authors’ views are not necessarily endorsed by the publisher.

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Winter 2017 | Intelligent Glass Solutions | 9

www.martifer.com

FENSTERBAU FRONTALE

EXECUTIVE BOARDROOM COMMENTARY

A World Class Event in Nürnberg In keeping with the long standing tradition before one of the world’s leading trade fairs for construction, windows, facades and materials at the Nürnberg Fair Ground, Maria Jasiewicz of IGS Magazine spent some quality time with Elke Harreiss, Director of this well established super event – FENSTERBAU FRONTALE. This meeting took place in the bustling city of London in October 2017. tradition, from 21st until the 24th March 2018 exhibitors and guests will return to the Nürnberg Exhibition Centre, to witness the event which takes place every 2 years. How much has it grown? IGS takes a look at the figures. 2016 was a record-breaking year with 110,581 visitors, from 119 countries and almost 794 exhibitors from 37 different countries. The future looks bright as visitor numbers are set to rise slightly, although exhibitor levels will stay the same. Ms Elke Harreiss explains, “the space is limited and we expect the same number of exhibitors in 2018, it’s all booked.’’ 2018 is a special year for FENSTERBAU FRONTALE as the successful trade show celebrates its 30th Anniversary of being held in Nürnberg. A slightly modified logo reflects its 30th jubilee, a fitting design to commemorate this celebration. We delve into the past with some interesting facts from the history of this event. The fair was organised for the first time by “Fachverband des Glaserhandwerks und verwandter Berufe in Württemberg-Baden e.V.” (English: Trade Association of glassing craftsmenship and related professions in Württemberg-Baden e.V) in Mosbach/ Baden in 1949, when it was called “Maschinen-, Werkzeugund Rohstoffschau” (English: “Machines, Tools and Material Show”) and featured 41 exhibitors. From 1968 on, it was called “fensterbau”. In 1988, it moved to Nürnberg. In 2000, an iconic year, the name FENSTERBAU FRONTALE was cemented and the fair developed and increased in size, diversity and geographical spread in terms of exhibitors and visitors. However, one thing remained the same; 30 years later FENSTERBAU is still held in the same grounds where it was moved after the original fairground in Mosbach/Baden became too small. In keeping with

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The biennial event brings together window and façade manufacturers, carpenters, architects and specialist tradesmen who gather in Nürnberg to showcase and find out about the latest developments in the sectors of profile systems, structural elements, glass in architecture, fixing equipment, safety equipment, machines, installations, the list is almost endless. If you are interested in keeping up with the trends and technologies in these evolving sectors and want to know the pertinent issues affecting and driving the window, door and façade industries, then FENSTERBAU FRO NTALE is a MUST SEE event. The success of FENSTERBAU FRONTALE is not only down to the hard working people who organize the event, but first and foremost the success has to be attributed to the very high standard of products on display and the quality of information provided. The exhibition of products and services is immense whilst the support is second to none. Deservedly, Elke is rightly proud of the show and its achievements and sums it up adequately in her motto,

Winter 2017 | Intelligent Glass Solutions | 11

EXECUTIVE BOARDROOM COMMENTARY

FENSTERBAU FRONTALE

“The greatest reward for our efforts is not what we receive for them, but what we have become as a result.” Much like the event, there has been an evolution in her own thoughts about the trade fair and the industry, “To be honest, before I was in charge of the trade fair, for me windows and doors were something that simply ﬁlled in the gaps in the outside walls of a building. But since I have been so heavily involved with the topic and the industry, I ﬁnd it fascinating how much technology it contains and how many different types of windows and doors there are all over the world.’’

Even after 17 years in the trade fair business I am still fascinated every time by all the hustle and bustle in the halls on the last set-up day.

As the saying goes, the proof of the pudding is in the eating, so when it comes to this event, an independent survey by the NürnbergMesse seeking the opinions of visitors and exhibitors on their thoughts, and how they perceive the trade fair, you taste the full ﬂavour of this world leading event.

The Verdict: • Out of the 794 exhibitors from 37 countries that took part in this survey, 95% rated the event an overall positive experience. • Nearly all respondents were able to reach their most important contact groups • 94% made new business contacts • Nine out of ten are expecting follow-on business from the show • Around two thirds of exhibitors considered the volume of visitors’ traffic and professional quality of visitors to be good or very good. • 95% were satisfied with the range of products and solutions on display at the stands • 9 out of 10 visitors rated the benefits of the trade show highly. The facts and figures don’t lie, and the outlook from this event is clear: a lot of satisfaction and fulfilled expectations from both visitors and exhibitors.

FENSTERBAU FRONTALE EVENT EXIBITOR DEMOGRAPHICS Joiners and carpenters (9%)

IGS: How much has FENSTERBAU FRONTALE changed since you became its leading lady in 2014 and what are you most proud of?

Shutter and Sunshade technicians (10%)

Component suppliers (11%)

12 | Intelligent Glass Solutions | Winter 2017

The IGS Interview:

Window manufacturers (62%)

Elke: I am very proud of the changing image of the interior of the trade show, particularly the individual stands. They have evolved from being very simple ﬁlled spaces with a lack of imagination and now resemble designer stands, with a cosmetic facelift. First impressions are very important, as is showcasing inviting products.

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FENSTERBAU FRONTALE

EXECUTIVE BOARDROOM COMMENTARY

Elke Harreiss In addition to this we are very proud of the innovations that are brought to the event with most companies coming to Nürnberg to debut and introduce their technologies to the large audience that the event attracts. Many companies exclusively wait to introduce their products and solutions speciﬁcally at our trade fair, and this is something that greatly pleases us. In recent years, companies have put a lot of effort and hard work with regard to the display of their innovative solutions and making

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their exhibition spaces look attractive and appealing. A desire for more sustainability and comfort continues to drive innovation in the window, door and facade construction sector, and that is one of the reasons that architects, manufacturers and the trade meet in Nürnberg to discuss the most important trends in the design, construction and management of energy-efﬁcient buildings. One of the central focuses this year is on solutions for the automation of windows and facades and it will be presented in a new and very special show.

Winter 2017 | Intelligent Glass Solutions | 13

EXECUTIVE BOARDROOM COMMENTARY

FENSTERBAU FRONTALE

IGS: FENSTERBAU FRONTALE runs parallel with the HOLZ-HANDWERK Fair dedicated to woodworking craft. Which one is more important to you? Elke: Both are dedicated to the same solution, sustainability and innovation with equal importance. We are a little bit like twins with both events representing innovation and change in their respective industries. They work together in synergy and form a unique and special combination.

IGS: What does the future hold for FENSTERBAU FRONTALE? Elke: There is no physical space to grow as we are limited in terms of the size of the grounds that the NürnbergMesse occupies. However we will develop and re-design the new South Entrance and adjoining halls. Hall 3C is currently being built and is going to be the latest show-stopper in the south-west corner of the exhibition grounds. Once again designed by Zaha Hadid’s architectural ofﬁce, hall 3C will meet the same quality and energy standards as hall 3A, which is one reason why it is so popular with our customers. The new south axis will give the impression of a slightly bigger space and add something to the imagery and special ambiance that this event has. IGS: And here we come to the most important question that everybody is asking: What will be the highlights for 2018? Are there any exciting new programmes FENSTERBAU FRONTALE will offer it’s visitors and exhibitors this year? Elke: In keeping with past events a number of traditional programme highlights will be kept, including the architects area, innovation awards and the architecture forum. However we are proud to debut two new programmes that we are sure will be well received: guided tours and an impulse forum. The Architects Area includes a small red Logo which leads visitors to relevant exhibitors with interesting products for architects and designers. As always, it will be very popular with architects coming to ﬁnd solutions and inspiration. There will be another edition of the Innovation Awards. As in past events, we will have the awards ceremony: The Innovation Awards for Architecture + Window Door Façades that will be presented by AIT and Xia Intelligente Architektur magazines to FENSTERBAU FRONTALE exhibitors. The Architecture forum is a combination of informative presentations on windows and facades exclusively run for architects and designers. Another collaborative programme will be run by the University of Applied Science in Bern (BFH), Switzerland and

14 | Intelligent Glass Solutions | Winter 2017

a number of Swiss industry associations that will present a series of seminars in a special show, ‘Windays Light on innovations from Switzerland’. For the first time we are introducing guided tours which will be very interesting and useful for craftsmen visiting the exhibition. We will guide them to the specific exhibitors and stands of leaders in the latest developments in sectors such as Smart Home/ Building Automation, Doors and their Metal Fittings,Ð Security Technology/Anti-Theft Protection, and Modern Windows for every Purpose. This will allow visitors to make the most of their time at the exhibition and steer them to exactly where they need to be to get the most value. Smart homes will be a focal topic in 2018 with a large bulk of the event dedicated to this expanding industry. We will have a special show Windows & Doors 4.0 organised in conjunction with ift Rosenheim, which will present the latest innovative research on the digitalisation of windows and doors for smart homes. It is our hope to build awareness on the planning, assembling and configuration of electronic components and the use of smart home technologies. This year, I am especially excited to present the newly established FENSTERBAU FRONTALE FORUM. For the first time in the events history there will be a designated presentation area in Hall 3A on various industry topics. It will focus on current industry issues like digitalisation, building automation, safety and practical tips for trade’s people. Experts in these fields will impart their knowledge in TED-style presentations and there will be a dedicated lounge for networking and meetings. In addition, we are very pleased to include job boards that will connect potential employees with employers, this is a fantastic initiative that adds to the other programmes and opportunities introduced for the first time.

IGS wraps up the interview with some final thoughts from Elke Elke: Even after 17 years in the trade fair business I am still fascinated every time by all the hustle and bustle in the halls on the last set-up day. There’s hammering and drilling going on, display cases are being filled and staff are getting their instructions at the exhibition stands. When you walk through the halls it’s hard to imagine that the trade fair will begin just 24 hours later. But the next morning everything is spick and span and organised and the exhibitors are ready to receive their visitors. The greatest feeling is when the hall doors open and the event that we have been focused on and working very hard on for two years finally gets under way. For more information visit: www.frontale.de Contact Details: frontale@nuernbergmesse.de

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IGSMAG.COM WELCOME TO OUR WORLD

Welcome to

our world!

Over the next 10 years 18 billion sqm of space will be designed by architects and engineers to shelter 1.5 billion people. An unbelievable stat provided by our hardworking brothers and sisters at ArchDaily and worth repeating to you here. Intelligent Glass Solutions magazine (IGS) serves as the source for inspiration, innovation and building design trends. With igsmag.com we pledge to complement the print magazine and bring you the latest news, technologies, developments and projects in the architectural glass and facade design and construction ďŹ eld. Our readers can enjoy absorbing content from authentic leaders of the industry, featuring amazing projects and case studies predominantly focused on glass, with informative and educational content that is rarely obtainable elsewhere.

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IGSMAG.COM

IGS magazine has reﬂected the industry’s momentum over the past 14 years by publishing expert testimony on the central issues that really matter

WELCOME TO OUR WORLD

FOR THE INDUSTRY

FOR OUR READERS

igsmag.com embraces exemplary projects and best practice within the industry. We work with pioneers who are spearheading technology in this transforming sector, and strive to bring their ﬁndings and results to our readers, fast. From magazine partners, videos, full length editorials and adverts, we offer you the perfect platform to reach your intended audience.

FEATURES: The features section within igsmag.com brings you the best of glass and facade architecture, Case studies, exclusive interviews, opinions from respected industry ﬁgures, and stunning architectural projects focused on glass. Many of our articles and content are written by renowned ﬁgures from inside the industry, giving our readers access to the thoughts and minds of key innovators in this transforming sector.

ADVERTS: Full and half page adverts in our print edition, prime advertising banners on our website, newsletter sponsorships plus unique products available in the IGS Shop. EDITORIALS: Interviews, press releases, articles on projects and products, events and innovative technology. PORTFOLIOS: We offer our partners in the glass industry a prominent spot on our website by creating a personalized portfolio page of your past, present and future projects with your beautiful pictures and project descriptions. A picture paints a thousand words. It’s an exciting time to strengthen your connections and intensify your engagement with this amazing architectural glass industry. Subscribe to: www.igsmag.com, do it now!

PORTFOLIOS: View past, present and future architecture from some of the most prominent architectural practices in the world. With amazing photography and project descriptions, readers can access inspiration and knowledge from the best and the brightest minds. PRESS RELEASES: Keep up to date with the latest press releases from glass, facade and architectural companies. Find out fast about the latest projects, technological developments, innovations in glass processing and gripping news stories.

MARKET TRENDS: igsmag. com brings you the latest in glass development, the hottest topics and industry trends. • Complex Geometry • Daylight in Buildings • Environmental/Sustainable/ Energy Efﬁciency • Glass Media Facades • Innovations in Glass • Intelligent Smart Glass • Super Tall Buildings TECHNOLOGY: We look at the latest developments in advanced glass technology, glass processing, glass protection, research, hurricane resistant/bomb blast resistant glazing, safety and security glazing, surface treatment, enhancement and modiﬁcation... EVENTS: Discover what is happening in the glass industry calendar. All about the events before and after they happen. We bring you exclusive news from relevant events and connect you with the world of facade engineering and glass architecture assemblies from all around the globe.

TO SUBSCRIBE GO TO: igsmag.com

IGSMAG.COM WELCOME TO OUR WORLD

We work with pioneers who are spearheading technology in this transforming sector, and strive to bring their ﬁndings and results to our readers, fast.

THE MEMBERS AREA – IGS ONLINE

HISTORY

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Winter

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Glass Intelligent

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EXECUTIVE BOARDROOM COMMENTARY

PEOPLE-CENTRIC

People-Centric Buildings designed with people in mind By Stephanie Akkaoui-Hughes, AKKA Architects

Stephanie Akkaoui Hughes Founder & CEO of AKKA Architects. Architect, speaker and author. AKKA is driven by Stephanie’s vision of Architecting Interaction. Based on Stephanie’s belief that interactions are the seeds of innovation, Architecting Interaction explores how spaces and contexts can foster human interactions. Stephanie is also an author and speaker. Stephanie’s book Architecting Interaction: How to Innovate through Interactions was launched early 2017.

20 | Intelligent Glass Solutions | Winter 2017

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PEOPLE-CENTRIC

EXECUTIVE BOARDROOM COMMENTARY

ALL OUR ACTIONS ARE INTERACTIONS An architect was asked to design a university campus. She designed the 3 department buildings and built them on site. Contrary to the expectation of the staff and students of the university she didn’t design any routes or pathways, instead she planted the whole campus with grass. After the ﬁrst semester, path formed in the grass and the architect then came back and paved these pathways as they emerged. Not only were the paths in unusual locations that she couldn’t have predicted, none of them were straight. The most important aspects of this story are the intelligence of users, the honesty of behaviour and the quality of time.

How can we gather the intelligence of users? Imagine you are standing at point A with a collection of bricks. You need to get the bricks to point B – which is about two meters away – without leaving your point A. What do you do? You may think of throwing the bricks. That would work. Now, imagine you are still standing at point A, but this time instead of bricks, you have a collection of birds. You need to get the birds to point B without leaving point A. Throwing the birds will not necessarily work, since they can ﬂy away wherever they please. Assuming that killing the birds and then throwing them – as

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some might suggest – is not an option. A better, more mature alternative would be to throw food for the birds to follow. This is an example of leadership by pull, not by push. It serves as an example of encouraging certain interactions by designing a fruitful context. To be leaders in the mature sense of the word, we have to shift from ‘designing for’ to ‘designing with’. We need to shift our leaders’ roles from being dictators to becoming facilitators. But what is facilitation? Let’s look at the architect story again. There are 3 provocative design guidelines I would like to emphasize

Winter 2017 | Intelligent Glass Solutions | 21

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PEOPLE-CENTRIC

from this story: the 3 qualities of facilitation.

need to facilitate their interactions.

• Incompleteness. The architect did not ﬁnish and seal the design, she didn’t dictate where the paths should be. Instead she left the campus incomplete as an invitation to the staff and students to participate designing incomplete invites interaction.

How can we harness the honesty of the user’s behaviour?

• Impermanence. The architect didn’t cover the site with asphalt, but grass, which is intrinsically ﬂexible, adaptable and allows for future change and development. Designing impermanent creates ﬂexibility and allows entities to be regenerated, recreated over time designing impermanent invites interaction • Imperfection. Remember the paths were in unusual location and none of them were straight. Facilitation is creating contexts that are incomplete, impermanent and imperfect, to invite other people’s inputs. Designing incomplete, impermanent & imperfect is how we facilitate. So to gather the intelligence of users, we

Even though I am an architect and trained to deal with form, I am not interested in form. I am much more interested in the ﬂow of things, in how people use a space for example, move around it, and interact with it. It is the void, what is not, that is the value of this space for example, allowing people to ﬂow. It is not what is built, but what is not, it is not the context, but rather the behaviour that the context empowers. It is not what it is, it is what it does.

This is not to say that the context does not matter, on the contrary. But it is not an end in itself, it is as important as the quality of interactions that it triggers.

This is not to say that the context does not matter, on the contrary. But it is not an end in itself, it is as important as the quality of interactions that it triggers. So to harness the honesty of behaviour, we need to move beyond conversation and into observation.

How can we utilise the quality of time? Oxford University in England is a very old college with very old buildings. One building

DO NOT DESIGN INTERACTIONS, INSTEAD DESIGN THE CONTEXT FOR INTERACTIONS

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PEOPLE-CENTRIC

in particular, a 150 years old building, is very special: its roof was made out of special oak beams – full length long beams of oak. After 150 years, the oak beams were beginning to rot and fall apart. So, the faculty came together and consulted about what needed to be done. What needed to be done was they had to replace the oak beams in the ceiling. They enquired about the cost and only one oak beam would cost them 100.000 pounds. Because, of course, it was the full length they were looking for. The faculty could not afford this. One of the younger members then said: ‘please, let me do some research on this’. Two weeks later, she came back and said: ‘I am very pleased you gave me the time to do the research, since we discovered that the architect who built this building 150 years ago planted a group of oak trees, speciﬁcally for this purpose’. This is sustainable design. Sustainability, green design, environmental design are not new concepts, they are very old concepts. Thinking into the future and facilitating the process, even 150 years ahead is how we can create systems that survive, that sustain themselves, sustainable systems. So to utilise the quality of time, we need to foster interactions along the 4th dimension.

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EXECUTIVE BOARDROOM COMMENTARY

Even though it is all about the interactions, I believe we should not design interactions. If we design interactions, we fall back into the role of dictators. Instead we need to facilitate interactions. We facilitate interactions by designing the context for interaction to emerge. Do not design interactions, instead design the context for interactions The question is how can we create contexts that foster interactions? This question is what drives my work, a few years ago I founded AKKA, an architecture and urban planning studio based in Amsterdam. Our work at AKKA is driven by the philosophy of architecting interaction. I believe that interactions are the seeds of innovation and so my vision focuses on fostering interactions to drive innovation.

We help companies innovate, since seeds of innovation is interactions we facilitate the right interactions. We do that not by dictating interactions, but by creating contexts where interactions emerge so by designing the space we help companies innovate through their space. Some of you might be thinking, that’s all good when building a new headquarters, or even when there is a plan to renovate

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EXECUTIVE BOARDROOM COMMENTARY

and move into an existing building, but what about when you have no plans to go anywhere? One of our clients came to us 3 months after moving into their brand new headquarters. They had hired a world famous architect, paid a few million euros only to move in the building and experience an epic failure. The building looked beautiful and did not work for them at all. This is where we came in and redesigned their space, without demolishing and while they continued to use it. We optimised it and made it into a living space. Instead of forcing people into beautiful form, we create the form around their ﬂows, the result is always beautiful, because it is natural and elegant. This is what we call a living space, a space that can support its users’ interactions. Even if you are not planning on building a new building or even moving to an existing one, you can always transform your current space into a living space, a context that fosters the interactions you want and helps you innovate. So the question is: how do we, practically speaking, help businesses innovate? How do we optimise their space to foster the right interactions? With our own process. Before I tell about our process and what it is about, let me share the usual architecture

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PEOPLE-CENTRIC

process. Traditionally architects design and build buildings. They work from the very beginning of design and until the end of construction when the building is ready to be inhabited. The minute people move in the space, architects’ leave. That is something I’ve personally never understood. I think that it is precisely when people move into the space that the building’s life begins and that is when as an architect, I want to be the most involved. I believe that our responsibility as architects extends into the life of the building. It is our responsibility to accompany the living building and its people as they settle with each other. Static architecture needs to extend into living architecting. One is the study of form, the other is facilitating ﬂows. Architecture deals with the form, architecting is dealing with the ﬂow.

So the question is: how do we, practically speaking, help businesses innovate? How do we optimise their space to foster the right interactions? With our own process.

This arch process does not work for us, we had to develop our own when designing for interactions, the deliverable goes beyond the physical. We created the AKKA process. An intrinsically collaborative process. Based on the communal creation of knowledge, this process is a 4 phased process, in which 3 of these stages take place before the delivery of the space, and the last phase happens postdelivery, after the space is born and people have moved into it.

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PEOPLE-CENTRIC

EXECUTIVE BOARDROOM COMMENTARY

DO NOT DESIGN INTERACTIONS, INSTEAD DESIGN THE CONTEXT FOR INTERACTIONS The underlying principle of the entire process is to gather the collective insights of the different proﬁles of people concerned by the projects. That is because we believe users are the experts in how they use the space. What we have discovered with many of our clients is that your space is holding your innovation back instead; it needs to hold your innovation path, support it, guide it. Your space is not only a backdrop to our activities. Most people, including architects think of space as a backdrop, the most beautiful, functional & inspiring backdrop. But space has another 2 roles to play. It needs to be a communicator, and communicate to anyone using or even visiting the space what your company is about, not by having the logo on the wall, but by communicating your values, vision, and

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strategy by the energy of the space. The 3rd and most important role of space is to be an active enabler. It is responsible to enable its users to live the values, strategy and vision of the company. Your space is a strategic tool that has the potential to support your corporate innovation, it is an asset, a strategic tool, so use it!

In summary, Architecting Interaction as a vision is bigger than architecture or urban development, it is about how to innovate your businesses through interactions.

In summary, Architecting Interaction as a vision is bigger than architecture or urban development, it is about how to innovate your businesses through interactions. I apply Architecting Interaction to architecture and urban development, those are my ﬁelds; you can apply it to your own ﬁeld, whatever that may be, because every area of our world needs to foster interactions, only different interactions and only to varying degrees.

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PEOPLE-CENTRIC

IT IS NOT WHAT IT IS IT IS WHAT IT DOES

CT 2: VISIE VAN AKKA OP DE ONTWERPOPGAVE

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26 | Intelligent Glass Solutions | Winter 2017

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PEOPLE-CENTRIC

EXECUTIVE BOARDROOM COMMENTARY

The essence of designing sustainably is creating contexts where interactions strive, and our role is not to dictate them but to facilitate them. Remember, we don’t design interactions; instead we design the context for it. We design the contexts for interactions by designing incomplete, impermanent and imperfect contexts and spaces, through a process that is in itself incomplete, impermanent and imperfect.

For more information about AKKA’s vision and process please visit our website www.akkaarchitects.com or download our book Architecting Interaction: How to innovate through Interactions written by Stephanie Akkaoui Hughes on Amazon.

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Winter 2017 | Intelligent Glass Solutions | 27

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trosifol@kuraray.com www.trosifol.com

INDUSTRY

LAKHTA CENTER INSIGHT

Europe’s tallest skyscraper in St. Petersburg Author: Dr. Jochen Mignat, DR. MIGNAT PR, Hanau

ith a preliminary height of 390m, the Lakhta Center in St. Petersburg, still under construction, is already the tallest skyscraper in Europe. When ﬁnished in time for the opening of the FIFA World Cup 2018, the tower is expected to reach a height of 462 m. The building is clad with a curved glass façade and a wide variety of façade types and sizes. Glazed atria at the ﬁve outside edges will be naturally ventilated and, together with other energy saving

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technologies, the Lakhta tower has been designed to fulﬁl the requirements of Green Building standards.

Like a winding needle, the tower is twisting up into the sky The new landmark of the Russian port metropolis is being built right by the sea and looks like a glass needle that is twisting smoothly upwards into the sky. The German company Josef Gartner GmbH is cladding the

The new landmark of the Russian port metropolis is being built right by the sea and looks like a glass needle that is twisting smoothly upwards into the sky.

Winter 2017 | Intelligent Glass Solutions | 29

INDUSTRY

LAKHTA CENTER INSIGHT

Business centre with several public functions Located right at the Gulf of Finland, the Lakhta Center is built on a construction site with a total of 170,000 m2. The Primorsky District, at a distance of 10 km north of the city centre of St. Petersburg, will also be home to a modern seaport for sea and river shipping. As a modern business centre with a number of public functions, Lakhta Center is expected to become the pumping heart of a new city thus providing relief to the historical city centre and strengthening the city’s function as the westernmost port metropolis of Russia. The tower is designed to be part of a building complex with a variety of freely accessible attractions including a viewing platform, cafés and restaurants, an amphitheatre, a health centre, a sports complex, research and educations facilities, cinemas and areas for events and exhibitions. This amazing building, the Lakhta Centre, will also accommodate the headquarters of the Gazprom group. In total, the tower has a gross storey area of approx. 163,000 m2.

Dr. Jochen Mignat

tower with an aluminium and steel façade and cold bent functional glass panels. The exterior façade with a total of 73,240 m2 consists of approx. 4.2 x 2.7m parallelogram shaped units with up to 40mm cold curved glass panes and opening vents in the corner areas of the building while the 25,410 m2 interior façades for the two-storey high atria mainly consist of rectangular units. The dynamic and slim shape of the new skyscraper results from its unique geometry. Designed by the British architect Tony Kettle and Gorproject SAO architects from Moscow, the tower reaches its greatest width in the middle and then tapers like a needle towards a spire-shape. Therefore, each of the 100 storeys of the tower has its unique size. The floor plan of each floor is based on the five building wings which are arranged around a cylindrical core. Furthermore, the ceilings of each storey are twisted towards each other at a degree of 0.82. Nevertheless, the tower seems to elegantly spiral up into the sky. Such an effect can be achieved with cold formed glass facades.

30 | Intelligent Glass Solutions | Winter 2017

The new building complex is characterized by energy-saving technologies for heating and cooling as well as for lighting, allowing for energy savings of up to 40 percent when compared to traditional buildings. For the expected international LEED Gold sustainability certiﬁcation, the façade plays a key role due its high level of thermal insulation, vastly improved use of daylight with panoramic glazing and as already mentioned, natural ventilation.

Approx. 100,000 square metres of facades made of aluminium, steel and cold bent glass With a total of approx. 100,000 m2, the façade made of aluminium, steel and cold curved glass represents the size of around 14 football ﬁelds. Large parallelogram shaped façade units give the skyscraper a very high degree of transparency. On the levels below ground, the façade is inclined outwards while the upper levels are inclined inwards. The special geometry of the building

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INDUSTRY

LAKHTA CENTER INSIGHT

with different storey sizes and the 0.82° twisted ceilings have been tremendously challenging for façade construction. Eight different main façade types had to be produced, with a total of 16,505 individual units, all different in size. The 4,210 units of type WT 1 for example, have an axle width of 2,780mm and are suspended at each storey of the building, the 3,470 units of type WT 2 still have the same axle width, however, they are fixed at steel beams over two storeys. Other façade types are different in their axle widths or they are especially designed for corner areas or for the spire as from floor level 90. Furthermore, the exact sizes of the units within one façade type differ depending on the individual storey. In addition, each individual unit is twisted in a different way. The spire is clad with steel facades and a stainless steel mesh as well as stainless steel profiles. Its elegant design is nearly as transparent as glass.

Uniformly curved glass panels without unevenness The façade has to follow the slight twisting of the floors towards each other. The three-dimensional frame of the individual units is composed of four straight profiles which are assembled to yield a non-planar unit. The aluminium profiles have been connected to one another with specific, spatially twisted mitres in order to achieve smooth transitions of the individual façade units without unwanted offsets. During production, the glasses are then cold-formed up to 40mm along one edge, pressed into position and then sealed. This process allows to achieve a seamlessly bent glazing. The real challenge is to bend the glasses at the same time as maintaining the high physical properties such as thermal und sun protection. This allows for production of uniformly curved glass panels without unevenness and without restrictions as to coating and printing. A key point is the mechanical fixing of the glass pane. The aluminium glass façade is fixed to steel beams spanning over two storeys despite the twisting of the storey ceilings. Such a steel beam has to absorb the wind loads of the two superposed façade units. As for the coldformed glazing, the planar glass panes are bent at one corner of the frame. This yields

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a ﬂat, twisted glass panel which creates a uniform twisting of the façade at each single storey as well as uniform reﬂections which are not broken by offsets.

Glazed atria with windows for natural ventilation

The exterior façade is suspended at slightly twisted steel beams which span across two storeys and absorb the wind loads of the superimposed façade units.

Between the five wings of a storey there are five glazed atria each which span over two storeys. This so-called buffer zone which is designed as a lounge or communication area, comprises approximately one fifth of the exterior façade area. In winter, this area serves as a heat buffer while in summer the exterior façade can be opened for natural ventilation by means of two window sashes (1.188 mm x 938 mm). Opening is realised by means of an electric motor and a central bus controller. This makes Lakhta Center one of the tallest buildings worldwide with the possibility of natural ventilation. The exterior façade is suspended at slightly twisted steel beams which span across two storeys and absorb the wind loads of the superimposed façade units.

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INDUSTRY

LAKHTA CENTER INSIGHT

units. This WT1 internal has the same shape as the exterior façade units, however, with a different glass composition. The WT4 is glazed with double insulating glass with 8mm low iron single glazing towards the buffer zone outwards and low-E coating at #2. To the room side, glazing is laminated safety glass made of 2 x 10 mm heat-strengthened low-iron glass with a reﬂective sun coating at #4 „Cool-Light ST Bright silver“ and black frit for edge covering at #5. WT1 internal is double insulating glass with 8 mm low iron single glazing to the exterior buffer zone and low-E coating at #2. To the room side, glazing is laminated safety glass made of 2 x 10mm heat-strengthened lowiron glass with reﬂective sun coating at #4 „Cool-Light ST Bright silver“.

The exterior façade is composed of parallelogram shaped units with a height of approx. 4.2m and a width of 2.7m.

Interior and exterior façades with differently coated glass Since the glass panes of the interior and the exterior facades are coated differently, special contrast effects arise at the five building edges of the tower. The WT 1 exterior façade and the WT 4 interior façade are glazed with highly reflecting glass panes for visual protection while glazing of the exterior façade towards the atria is very transparent. The exterior façade is composed of parallelogram shaped units with a height of approx. 4.2m and a width of 2.7m. One façade area has been glazed with double insulating glass made of 1 x laminated safety glass with 2 x 8 mm heat strengthened low-iron outwards and HP coating at #4 „ Cool-Lite SKN 176 II“. The glass pane to the room side is 8mm low iron single glazing. The other façade area in front of the buffer zone has been glazed with double insulating glass made of 1 x VSG with 2 x 8mm heat strengthened low-iron outwards, reflective sun coating at #2 „Ipasol Bright white“ and HP coating at #4 „Stopray vision 72CT“. The glass pane to the room side is 8mm low iron single glazing. The interior façade is mainly composed of the WT4 façade with rectangular glass panels and, for a minor part, of WT1 internal façade

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Aluminium profiles and steel manufacture in Gundelfingen, assembly in Levashovo The aluminium profiles have been mainly produced at the Gartner headquarters in Gundelfingen (Germany). The WT1 and WT2 units have then been assembled in Saint Petersburg at the Gartner plant Levashovo while the WT3 units and the corner posts to close the corners have been assembled in Gundelfingen. Steel manufacture has been completely made at Gartner in Gundelfingen. The finished units have been stored in Levashovo and carried to the constructions site when needed. Adjustment of the façade units at the construction site has also been taken care of by the Levashovo plant.

Construction Project Signboard Architect: Tony Kettle und Gorproject SAO, Moskau Building owner: JSC Lakhta Center, a subsidiary of Gazprom Neft General contractor, site management, client for Josef Gartner: RENAISSANCE CONSTRUCTION CJSC Façade : Josef Gartner GmbH www.lakhta.center/en

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IGS 09 2013 IFC-OBC indd 3

23/09/2013 11:10

INDUSTRY

THIN-PROFILE INSULATION INSIGHT

Thin proﬁle insulation creates space for design freedom By Stanley Yee, Dowsil

Gone are the days when inexpensive energy made it possible to design buildings with little regard for energy performance but…. constructing environmentally responsible buildings are perceived to be at the risk of compromising design freedom. As energy codes continue to evolve and mandate increased thermal performance in insulation – and, in turn, reductions in energy consumption – building construction is subject to a range of local, state and national building standards, as well pressure to comply with voluntary standards and certifications. But with help from industry-leading construction innovators, architects are meeting and exceeding those challenges, delivering performance with aesthetics. A new thin profile high performance insulation is providing architects with some additional working and tolerance spaces – enabling energy code compliance in tight, space confined areas. Achieving higher performing construction and meeting stringent building codes often comes with the concessions made in the architectural detailing, along with the need for extraordinary equipment and techniques. Recognizing the need for solutions that meet new requirements but are consistent and familiar with existing building and construction processes, Dow Corning?? has developed a new high-per-

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INDUSTRY

THIN-PROFILE INSULATION INSIGHT

formance insulation material. Based on aerogel technology originally used in specialized applications such as those in the aerospace industry, Dow Corning® HPI-1000 Building Insulation Blanket is a silica based aerogel incorporated into a blanket medium that gives rise to a comparatively more thermally resistant insulation solution that is finding a niche, providing thermal resistance in tight, space restricted construction areas. Dow Corning HPI-1000 Building Insulation Blanket is a flexible, thin profile, construction friendly material that can be cut to size on the job site and applied to reduce the thermal bridging at specific locations in a building envelope assembly. It is highly resistant to flame, with an ASTM E84 Class A fire rating (flame spread index 5, smoke developed index 10). This flexible and thin insulation material is already helping architects and building engineers meet their sustainable building challenges, as illustrated in two recent installations.

Meeting changing code requirements Evolving code requirements and their interpretation can leave architects scrambling to update construction details while trying to maintain the original design intent. Construction of the Stadium Place West Tower in Seattle, Washington, faced just such a challenge. Situated in Pioneer Square, one of downtown Seattle’s most historic districts, the Stadium Place project aimed to offer a mix of commercial and residential development to revitalize the neighborhood, beginning with the development of the 11-story Nolo apartment building. All stakeholders involved in the project wanted to make certain this building and the entire complex embodied the architectural qualities of the area. To reﬂect the historical style of the neighborhood, architects designed the West Tower to have depth and relief in the façade, with the brick surrounding the windows to have a step back – a challenging situation for conventional insulation materials in an era of lightweight construction in contrast to solid masonry construction used when the neighborhood was originally built.

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Figure 1. Dow Corning® HPI-1000 Building Insulation Blanket. Further complicating the design challenge were the energy performance criteria put in place by the City of Seattle in 2009, intended to reduce the amount of thermal bridging allowed in the exterior wall assemblies of newly constructed buildings. The code stipulates inclusion of a layer of insulation outside of the building’s air barrier to avoid one of the most common forms of thermal bridging.

Evolving code requirements can leave architects scrambling to update construction details without losing sight of their vision. Construction of the Stadium Place West Tower in Seattle, Washington, faced just such a challenge.

To meet these requirements at recessed brick conditions, the architects had limited options. They could offset the exterior sheathing line from a 150mm exterior stud to 100mm and sheath around it, but this would be complicated and messy. Or, they could find a thinner insulation product with the same R-value, which would enable the cleaner, easier-toframe window jamb originally envisioned. Morrison Hershfield, an engineering consultancy, recognized the unique problem facing the Stadium Place development. Working with ZGF Architects, the consultancy specified Dow Corning HPI-1000 Building Insulation Blanket as the solution to insulate the resulting thermal bridge where brick returns to meet the window wall. The higher thermally resistant thin, and flexible insulation material was cut to fit to insulate this gap around the window like a picture frame. Its thin profile and flexibility allowed the building to meet the City of Seattle’s requirements for both continuous insulation and thermal bridging. The capacity to use an insulation material that could provide the separation between the exterior brick and its supporting wall enabled the capacity to continue to achieve a visually clean return and superior R-value without compromising aesthetics.

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INDUSTRY

THIN-PROFILE INSULATION INSIGHT

Figure 2. Thin-profile Dow Corning® HPI-1000 Building Insulation Blanket was cut to fit, then installed around window jambs to insulate the area where brick returns to meet the window wall – satisfying Seattle’s requirements for both continuous insulation and thermal bridging. As an added benefit, the building insulation blanket is very vapor-permeable, which is especially important in wetter climates like Seattle’s. The required R-value could be obtained without creating concerns about unintended moisture accumulation in the wall assembly.

windows. Bolted to the wall, the 18 x 457mm metal shades created thermal bridging challenges, essentially operating as “reverse radiators.” The stringent insulation requirements to meet Passive House standards made minimizing heat loss in this area crucial.

For the Stadium Place development, use of the Dow Corning HPI-1000 Building Insulation Blanket resolved a design challenge without signiﬁcant cost implications. It simpliﬁed the detail and kept its function while also improving integrity within the air barrier.

GBD Architects, Inc., worked with Dow Corning to specify Dow Corning HPI-1000 Building Insulation Blanket, which was cut to ﬁt the sunshade attachment area (see Figure 3). Featuring R 9.6 per inch insulation performance, the blanket reduces heat loss and minimizes the potential for thermal bridging – without altering aesthetics of the window shade design.

Isolating thermal bridging challenges High-performance thin insulation also can help buildings meet the toughest standards, such as those targeted by the Kiln Apartments in Portland, Oregon.

Builders of the Kiln Apartments not only met Oregon building codes that are more rigid than the national average, but also achieved their goal of obtaining Passive House Institute US (PHIUS) Certiﬁcation.

With the goal of becoming one of the most energy efficient multi-family housing buildings in the U.S., the Kiln Apartments building pursued the aggressive “Passive House” standard for energy efficiency. The standard, which originated in Germany, often results in buildings 80 to 90 percent more efficient than the average home in the U.S. For the Kiln Apartments, meeting this standard would require more than simply increasing the amount of conventional insulation – which would be neither practical nor aesthetically pleasing. One design feature of the Kiln Apartments is sunshade thermal shims that were installed like visors on the top edge of the building’s

36 | Intelligent Glass Solutions | Winter 2017

Figure 3. Dow Corning® HPI-1000 Building Insulation Blanket thermally isolates a stainless steel sunshade support.

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INDUSTRY

THIN-PROFILE INSULATION INSIGHT

Predicting performance benefits through modeling Even when standards are less demanding than those of Passive House, addressing thermal bridging concerns is important. To determine how effective thin profile blanket insulation can be in mitigating thermal losses, three common construction details were modeled: • Curtainwall-at-grade detail with the aerogel blanket applied from the neck of the curtainwall to the below-grade rigid insulation, resulting in a reduction in linear thermal transmittance approaching 25% • Curtainwall jamb at the exterior and interior insulated steel stud assembly with the aerogel blanket applied around the adjacent steel stud and at the wall-to-curtainwall transition, resulting in a reduction in linear thermal transmittance approaching 70% • Rehabilitated window-wall system with the aerogel blanket at the slab edge and around vertical and horizontal glazing mullions, resulting in a reduction in linear thermal transmittance approaching 53% Two conceptual whole-building energy models were run to demonstrate the effect of using building insulation blankets with both conventional and higher-performance assemblies to minimize thermal bridging: • For a building with the glazing system covering 100% of the façade area, addition of the aerogel blanket and conventional assemblies resulted in a 3.56% energy savings. • For a façade with curtainwall glazing and a steel stud wall assembly, addition of the aerogel blanket and higher-performing assemblies resulted in a 6.78% energy savings. The determined linear lineal transmittance values can readily be incorporated into thermal models, eliminating guesswork and improving the predictability of the heat loss, helping architects and builders achieve their sustainability goals without sacrificing design freedom. Additionally, 3-D thermal modeling is an enabler of more informed design choices – for system selection and for detail development

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Inside minimum temperature indices without Dow Corning® HPI-1000 Building Insulaton Blanket

Figure 4. Thermal modeling demonstrating the use of Dow Corning® HPI-1000 Building Insulation Blanket along slab face and vertical and horizontal mullions of a window-wall spandrel section.

for visual impact. One of the outputs of 3-D thermal modeling is the isotherms – a depiction of material surface temperatures showing the variation as one reads them from the exterior of the building towards the interior. This variation is expressed in different colors: blue for cold and red for hot.

When compared to conventional insulation, Dow Corning HPI-1000 Building Insulation Blanket delivers signiﬁcantly improved thermal resistance.

Using an interior temperature of 21°C and an exterior temperature of -14.5°C, 3-D thermal modeling of a typical thermal bridging condition shows the impact that using Dow Corning HPI-1000 Building Insulation Blanket has on the surface temperatures of the system (see Figure 4). Using the insulation blanket, the minimum temperature showed a 10.6% improvement on the glazing, a 13.3% improvement on the frame and a 15.2% improvement on concrete.

Solutions for tomorrow’s sustainable building challenges When compared to conventional insulation, Dow Corning HPI-1000 Building Insulation Blanket clearly delivers significantly improved thermal resistance. Its unique combination of thermal conductivity, fire resistance, vapor permeability, flexibility and ease of installation makes it an ideal material for use in building and construction. For architects and design engineers, this thin insulation technology may be a key material in meeting next generation sustainable building challenges.

Stanley Yee, a LEED® Accredited Professional, is a façade design and construction specialist for Dow Corning Corporation in Midland, Michigan. Yee’s specialties include design assistance and support; building enclosure air, water and thermal control; waterprooﬁng; and testing of enclosure performance. For more information about high performance insulation solutions from Dow Corning, visit dowcorning.com/HPInsulation.

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WORLD EXCLUSIVE: It must be SEEN to be believed

Waldstatt, December 2017. Products with that special something – at SEEN, individuality and attention to detail are of particular importance. This is where the variety of products are just as impressive as the projects in which they are used. The latest offer by the company: shiny shapes in glass.

Squares, reﬂective, regular

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Circles, reﬂective, regular

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It must be SEEN to be believed

Author: Rouven Seidler, Seen GmbH

WORLD EXCLUSIVE:

All those who are looking for exceptional implementation options in architecture, interior design or the execution of their design ideas, will find SEEN to be just the right partner. The high-quality product range is extremely versatile and provides a wide range of optics, haptics, light, and shapes. Among other things, it includes thin stone with its unique naturalness, which can be used in various ways through the connection with glass or on different carrier materials. In addition, extravagant acrylic glass with special, three-dimensional insertions represents a special highlight for every room. A particular shine is also shown by the latest development, which now extends the range: a special, two-sided inlay for laminated glass or laminated safety glass. It consists of individual, small forms, which exhibit a high degree of flexibility in shape and size – anything from square, rectangle or circle to company logos is possible. In addition to various non-shiny wood veneers, the specificity of the product lies in a version of the partial pieces out of a metallic reflective material with the two high, and semi-reflective basic versions. The individual small forms with a size between two and twenty millimeters

Circles, black rear, regular

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Circles, reﬂective, regular

Winter 2017 | Intelligent Glass Solutions | 39

WORLD EXCLUSIVE: It must be SEEN to be believed are ﬁxated on a transparent substrate. Up to ﬁve different types can be used per glass, while the maximum pane width is 3.2 meters with a maximum possible length of up to twenty meters which will accommodate todays most advanced glass panels, so here too, there is plenty of room for creative leeway. Uniformly applied rows and grid structures are just as possible as partial surfaces, gradients, and lettering. The space between the shapes can be determined freely. A simple PDF template is enough to transfer the personal preferences onto the inlay.

introduction took place in mid-November at the World Architecture Festival in Berlin. The planning of projects that incorporate the “new look” can therefore begin straight away. Starting from January, additional tests are to be undertaken at a German testing institute, so that from April 2018 queries regarding durability can be confidently answered on the basis of an official and independent test report. The UV tests will take a further three months before the results will be known. The classification as a laminated safety glass can be assumed.

A particularly beautiful effect is achieved if the desired elements are coated black on one side. In the lamination process, the different expansion coefficients of differently weighted surfaces cause the individual forms to curve slightly so that a threedimensional effect arises, which is particularly visible on the metallic side. In addition to the significant depth of view, this provides a distinct vitality in the glass element, as the reflections of incident light and colors are thrown back on all sides.

And of course, SEEN will not stop creating new ideas, as further design variants and combinations are already in the pipeline. This is where, in addition to the described design options, the photometric characteristics of the overall glazing play an important role. It is assumed that depending on the percent coverage of the glass surface, a signiﬁcant reduction of the g value and the light transmission can be achieved through the forms. This ensures a wide range of options for the glass coating as both a curtain laminated glass façade or an outer element of an insulating glass unit. Particularly for Central Europe, depending on the degree of coverage, one will predominantly have to work with a low-e coating on the inner insulated glass, which is normally more neutral in colour than a sun protection coating. Furthermore, the sparsely reﬂective exterior suggests a positive impact on the protection of birds, which is also an important factor and is being tested accordingly.

This two-sided processing is often the case with façade applications, as it enables a perfectly opposite effect for interior and exterior spaces. While the pattern shows only black inside, so that the view through the pane is hardly or not at all disturbed, the outer shell of the building shimmers and shines in a particularly multifaceted way. In addition, the possibilities of digital printing on the metallic insert are currently being ascertained. This would make all colors feasible, while the reﬂections actually remained to a large extent. Experience gathered in the past shows that the chances in terms of UV stability of the surfaces are very good. So far, the development of the product has taken approximately eight months, and the tests with different glass processing facilities have shown positive results without exception. After an initial presentation for architects, designers, and engineers in New York and also in London, the ofﬁcial market

Rectangles, black rear, regular

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Thus, the company is well-positioned with the different types of thin stone applications, its special acrylic glass types, as well as the new inhouse development. And the fact still applies that all manner of project-speciﬁc, cross-industry, and individual items that already exist can be developed at any time. For further information and ideas please visit: www.seengmbh.com

Circles, black rear, regular

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We’re far from done yet…

There’s still plenty more to come… Just turn the page to read Marcin Brzezicki of Wroclaw University in Poland’s feature about the growing popularity of glass ﬁns, horizontal or vertical, decorative or functional you name it and read about it here on page 42, it’s great. Then of course the inimitable Paul Bastianen rounds up the GPD conference from the summer of 2017 and when you get to page 55 he provides us with an historic overview of the Glass Supper, just because.... It was such a monumental occasion we are compelled to herald our tribute to GPD by publishing some 50 pages of technical papers from Finland, folks this is IGS, get your glass engineering degree right here starting on page 60.

Enjoy your reading!

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MARKET INTELLIGENCE: TRANSPARENT FACADES

New trends in the architecture of transparent facades Its been observed recently that the use of glass fins (ribs) has been rapidly growing and has been marked as a strong emerging trend – not to dive into the complicated definitions – long glass strips mounted in a perpendicular fashion to the surface of the façade. The fins can be mounted in both: horizontal and/or vertical positions. Fins are used as decorative (formal enrichment of the facade), functional (sun shade) and structural (stiffening and load-bearing) element of the facade. Overall, the trend of using glass fins is a result of the abundance of proper quality glass, that allows for safe use of relatively small elements that are point mounted. This trend with the increased use of glass fins deserves a closer look which we will do in a short review, illustrated with photographs taken on-site showing the different areas of application. Auth Au tho orr: Ma Marrc ciin n Brz rze ez zic cki ki, W ki, Wrroc ocla law aw U Un niv iver ersi sity ty of S Sc cie ienc nce a an nd T Te ech chno chno nolo og gy y

42 | Intelligent Glass Solutions | Winter 2017

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42 | Intelligent Glass Solutions | Winter 2017

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MARKET INTELLIGENCE: TRANSPARENT FACADES

Contemporary architectural transparency (understood as the optical property of transmitting light through material) is constantly being redefined and, over the last decade, new design trends have developed related to transparent façades in architecture. Those trends are the result of dynamic technological progress and of the advancement in the field of materials science. Transparency is no longer limited to specific functions (e.g. illumination of the interior), but has become a tool of formal expression itself. Apart from the standard understanding of transparency as the use of light-permeable materials in façade design, one can find other innovative and creative interpretations. Glass fins became one of the fundamental elements of this abundant transparency trend around the 1950’s.

Methodology This short preview of the application of glass ﬁns is based on general morphology studies of transparent facades that the author conducted from 2015 to 2017. This allowed for the isolation of one of the main trends – a glass ﬁn trend that, as the author believes, deserves a short review. Its description is followed by on-site made photographs showing different areas of application.

Glass fin trend Glass fins (also called ribs or lamellas) could be defined as long glass strips mounted to the surface of the façade. The fins are mounted in both: horizontal and vertical position and at different angles in the relation to the façade’s surface. Fins are used as structural, functional and decorative element of the facade. The occurrence of this trend is obviously related with the development in the area of glass fittings, mounting and lamination. This allows narrow strips to be manufactured and safely point or edge mounted to the façade at a varying heights.

Glass ﬁn as a structural element

Fig 6: Swiss Tech Convention Center (arch. Richter Dahl Rocha & Associés, 2014)

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This short preview offers no space for the detailed presentation of structural characteristics of glass fins, but at least some of the issues can be discussed. Structural glass fins are mainly the result of the architect’s and their clients desire to create so-called all glass facades. The use of this system dates back to the 1950s, when fins were used to stabilize shop windows with one of the first applications being at the Maison de la Radio in Paris (arch. Henry

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MARKET INTELLIGENCE: TRANSPARENT FACADES

Bernard, 1952-1963). Glass fins from the structural point of view replaced the opaque vertical mullions in classic curtain-wall façade systems. The successful application of this system in the first buildings – e.g. Willis Faber & Dumas Headquarters by Foster and Partners, where the façade is partially hung from above using glass fins – facilitated the spread of this type of system and pushed the technology for the creation of new developments. Glass fins are connected to the façade glazing by means of patch fittings, corner connections or point mount fittings. Available systems are numerous, offering the fin height up to 12-15 meters [3]. The patch fittings and point-mounting systems were subsequently introduced. Steel plates are also laminated between the layers of glass forming glass fins. Plates are later used to connect elements of the facade and to provide the proper load transfer. The most challenging aspect of a glass-fin wall “occurs when the span is too great to be accommodated by a single piece fin, and a splice detail must be developed to create a fin comprised of multiple glass pieces” [5]. Initially longer fins had to be connected by the means of patch plates to fix smaller fins together, but laminated tempered glass fin technology allows for laminated fins to be

Fig 1: Apple Store Boylston Street in Boston (arch. Bohlin Cywinski Jackson, 2008)

produced over 40 feet tall in one piece (e.g. by Sedak). Structural engineers use glass fins as means of stiffening the structure. Their orientation is usually perpendicular to the surface of the glazed façade. Fins are used to make glazed walls more rigid, to reduce deflections and to improve bearing capacity of horizontal loads – they usually “carry wind positive pressure and suction forces” [1]. Dr.Jan Wurm writes, that from the structural point of view, fins are “normally suspended and any movements in the primary structure are accommodated at the bottom support of the fin” [1, p. 108].

Fins are used make glazed walls more rigid, to reduce deﬂections and to improve bearing capacity of horizontal loads – they usually “carry wind positive pressure and suction forces”

Fins are usually made of laminated glass but might be also monolithic. Beside the structural differences, there are some visual constrains concerning the use of laminated fins as “these systems may seem thicker than monolithic fins when viewed from the inside on an angle or from directly behind (…) even with ultra-clear, low-iron glass” [2]. Even if the interlayer used to laminate the glass is clear, it will still be somewhat visible from inside. This effect could be seen in the Apple Store Boylston Street in Boston (arch. Bohlin Cywinski Jackson, 2008), where glass fins are manufactured from 5 panes of glass with structural interlayer material, visibly

Fig 2: Tamedia Ernst-Nobs Platz Headquarter (arch. Atelier WW, 2001)

Fig 3: Canada Place at Canary Wharf, (arch. Zeidler Partnership Architects, 2003)

44 | Intelligent Glass Solutions | Winter 2017

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MARKET INTELLIGENCE: TRANSPARENT FACADES

affecting the transparency of this element (see Fig. 1). In this particular case fins are rigidly connected with the beams forming one continuous element (a portal frame). Although beam looks similar to the fin, it is subjected to bending force and resulting buckling, thus has to be designed differently. The elements are connected by means of polished stainless steel fittings.

Glass fin as a functional element Functional glass fins are used as shading elements, thus fins become louvers. Usually horizontally oriented they block the sun and allow users of the building to enjoy Fig 4: Federal Office Building in San Francisco (arch. Morphosis, 2007)

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uninterrupted outside views. Louvers used as shading require more maintenance, as the horizontal position facilities the dirt accumulation. In some cases horizontal glass louvers are motorized and adjust to the sunlight angle. One of the most complicated mechanical glass louver retracting systems was developed at the end of 1990’s in Zurich, at the Tamedia Ernst-Nobs Platz Headquarter (arch. Atelier WW, 2001). Opaque glass louvers are motorized using the pantograph system that lowers them into the correct position by means of regulating the length of steel cables. The bona ﬁde glass transparent ﬁns are used as support for guiding rails for this mechanism (see. Fig. 2).

Louvers used as shading require more maintenance, as the horizontal position facilities the dirt accumulation. In some cases horizontal glass louvers are motorized and adjust to the sunlight angle.

Fig 5: INES – French National Solar Energy Institute (arch. Atelier Michel Rémon + Agence Frédéric Nicolas, 2013)

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MARKET INTELLIGENCE: TRANSPARENT FACADES

Fins for shading are also used in a vertical position, this makes them less prone to dirt and soiling. External vertical glass fins are also used as a light diffusing element, and are therefore called baffles (performing the function of what’s commonly called a vertical light shelf). For even more effective light scattering vertical glass fins are manufactured as translucent elements, e.g. sandblasted or frit-printed as “when they are (…) diffusive, they can help evenly distribute light without reducing the total amount of light significantly” [4] and might contribute to the overall glare reduction in the office rooms e.g. like in Canada Place at Canary Wharf, (arch. Zeidler Partnership Architects, 2003), see Fig 3. Sandblasted fins located on the northern façade of Federal Office Building in San Francisco (arch. Morphosis, 2007) are used as a light redirecting device (see Fig. 4) while screen printed fins on the western façade of INES – French National Solar Energy Institute (arch. Atelier Michel Rémon + Agence Frédéric Nicolas, 2013) are used as both: light redirection (during the peak hours of the day) and as a shading device (in the afternoon – see Fig. 5). Glass fins in INES could be pivoted around the vertical axis by means of electric actuators (one actuator controls four fins at one floor height). A

Fig 7: Istituto Atesino di Sviluppo (arch. Renzo Piano Building Workshop, 2013)

46 | Intelligent Glass Solutions | Winter 2017

similar system was applied in Galizia Fashion Plaza building, in German city of Metzingen. Glass fins are also used as a PV cells carrier producing so-called shadovoltaic element. PV cells are usually laminated between two panes of glass which facilitates the process of production and protects the cells from the influence of weather. Installation orientation might vary depending on the prospected outcome. In Swiss Tech Convention Center (arch. Richter Dahl Rocha & Associés, 2014) dyed transparent cells are installed in the form of glass lamellas in vertical orientation and slanted at a slight oblique angle, allowing for easy air flow but still remaining visible from the inside of the building (see Fig. 6. Main Image on title page). Good ventilation results in the surface temperature drop of PV cell making them more effective in terms of energy production [6]. In Merck’s Innovation Center in Darmstadt (arch. Henn Architekten, 2015) the company Colt installed a total of 74 photovoltaic fins for generating electrical energy. Some of them are static and located perpendicular to the surface of the façade, but 17 fins are vertically pivoted to follow the sun and increase the energy gain. The rotatable solar cells generate electricity and at the same time provide shading and heat reflection. Efficiencies

The rotatable solar cells generate electricity and at the same time provide shading and heat reﬂection.

Fig 8: Dichroic Light Field in New York (arch. James Carpenter, 1995)

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MARKET INTELLIGENCE: TRANSPARENT FACADES

beyond 12 percent can be reproduced in the laboratory, while range from 2 to 3 percent is achievable in large-scale applications. Similar application of glass ﬁns can be observed at the headquarters of private equity ﬁrm Istituto Atesino di Sviluppo (arch. Renzo Piano Building Workshop, 2013) located in Le Albere district in Trento. In this case the PV elements laminated between panes of glass form horizontal louvers, that both protect the building from the sun and generate electricity (see Fig.7).

Glass fin as a decorative element Glass fins are used also as an eye-catching element. Fins (usually in this case called lamellas) that are located perpendicular to the façade allow to change the façade appearance depending on the viewer’s position. The buildings seem massive from the oblique perspective and light and airy if viewed frontally. This is also frequently connected with the experiments with the material itself; the decorative fins are sand blasted, pattern decorated, painted, and coated in special coatings (e.g. the spectral selective coatings) like in an art installation called Dichroic Light Field in New York (arch. James Carpenter, 1995) – see. Fig 8. G fins are also frequently used as a

Fig 9: W16 building in Brussels (arch. Conix RDBM Architects, 2009)

substitution of sculptural decoration that flat glazed facades lack. Many efforts in this field lead to the creation of impressive cases in the application of glass fins as strictly decorative elements. One of the most impressive cases of the decorative fins application is the W16 building in Brussels (arch. Conix RDBM Architects, 2009), where glass fins are twisted around a vertical axis and edge mounted to the floor plates projecting from the building. The glass in the fins is cold bent, offering an unprecedented amount of distorted reflections when viewed from the oblique angle (see Fig. 9).

At the same time, ﬁns are shading and energy harvesting elements, while simultaneously producing an interesting optical outcome.

Conclusion Glass fins can be used as either a functional element or a decorative one. As structural glazing develops over time, the fins are systematically included in the facades as load-bearing elements, allowing for the replacement of non-transparent mullions. At the same time, fins are shading and energy harvesting elements, while simultaneously producing an interesting aesthetical outcome. The fins have undoubtedly become part of the contemporary glazed facades of today, fulfilling many functions and offering multiple visual effects.

Acknowledgments This paper was funded by the Polish National Science Centre grant entitled: “New trends in architecture of transparent facades – formal experiments, technological innovations ”, ref. no. 2014/15/B/ ST8/00191. References 1. Wurm J., Glass Structures: Design and Construction of Self-supporting Skins, Springer Science & Business Media, 2007 2. http://www.wwglass.com/blog/post/laminatedglass-fins-vs-tempered-monolithic-glass-fins/ 3. http://www.sentechas.com/glass_fin_structures. html 4. https://sustainabilityworkshop.autodesk.com/ buildings/redirecting-light 5. Glass Fin, at http://www.enclos.com/service-andtechnology/technology/structural-glass-facades/ facade-structures/glass-fin 6. Magdalena Muszynska-Lanowy, Fotowoltaiczne systemy przeciwsłoneczne, Swiat Szkła, 6/2010

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Winter 2017 | Intelligent Glass Solutions | 47

MARKET INTELLIGENCE: TRANSPARENT FACADES

Windows getting smart

This year, the organization switched venues from Tampere Hal, to the TĂ¤hti Areena, a large event hall that accommodated the plenary sessions, parallel presentations, the exhibition, and a new initiative that allowed companies to exhibit innovations for the glass industry, with a particular focus on startups.

48 | Intelligent Glass Solutions | Winter 2017

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MARKET INTELLIGENCE: TRANSPARENT FACADES The IGS Column of Paul Bastianen

This year’s GPD (glass performance days) in Finland was a special one, representing it’s 25th anniversary. The inaugural event in 1992 began with a small group of 30 participants, customers of the tempering oven producer Tamglass (known today as Glaston), and has become one of the most important congresses in the glass sector. In these 25 years there have been an astounding total of 14,000 participants, 1,000 keynote speakers, 3,000 presentations and 10,000 pages of technical documents.

FASTER

The expectation of Bernard Savaëte for the future are heavily inﬂuenced by macro trends and parallel industries and sectors: global population growth and urbanization, developments in building and construction, diversifying technologies like 3D printing, the continued focus on CO2 emissions, self-driving cars and growing internet applications with new functionalities.

This year, the organization switched venues from Tampere Hal, to the Tähti Areena, a large event hall that accommodated the plenary sessions, parallel presentations, the exhibition, and a new initiative that allowed companies to exhibit innovations for the glass industry, with a particular focus on startups. The initiative supported and alluded to the main focus and trend of this year’s congress: the willingness of the industry for more cooperation and attention to startups. In addition, emphasis was placed on development, particularly signiﬁcant developments in the ﬁelds of smart-and power windows, integrated systems to windows that generate energy, while still maintaining a focus on great displays.

The world has changed dramatically over the last 25 years; globalization and the rise of ‘interconnectivity’, multinational corporations and mass knowledge have shaped the way forward. The Internet, google, linkedIn, facebook, twitter, mobile phones, renewable energy, climate change, terrorism and the ﬁnancial crisis of 2008 have all contributed in some way to the changing face and technologies within the glass industry.

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Winter 2017 | Intelligent Glass Solutions | 49

MARKET INTELLIGENCE: TRANSPARENT FACADES

The first opening keynote speaker, Bernard Savaëte, looked back over the last 25 years of GPD and how the glass industry has developed during this period and expectations for the future. This section provides IGS readers with a brief synopsis of this engaging presentation. As highlighted by Mr Savaëte, the world has changed dramatically over the last 25 years; globalization and the rise of ‘interconnectivity’, multinational corporations and mass knowledge have shaped the way forward. The Internet, google, linkedIn, facebook, twitter, mobile phones, renewable energy, climate change, terrorism and the financial crisis of 2008 have all contributed in some way to the changing face and technologies within the glass industry. To substantiate this notion, below is a look at some telling figures. Moreover, during this period selling prices have dropped, the glass industry has expanded and become active worldwide, while processors have still remained local. The last 25 years have, however, not been characterized by breakthrough innovations except in the field of coatings. 4 key words stand out: triple (triple insulation glass), low for low emissivity and low iron, temperable (coatings in particular) and extra for extra bright and extra large (insulation and laminated glass with dimensions of 18 x 3 meters). There have been significant efforts towards development, prime examples include glass tempering under 3mm thickness with improved flatness, complex bending for buildings and the automotive industry, laminated glass without autoclaves, digital printing on glass, machinery that is able to handle “soft” coatings, automatic lines to produce insulation glass, quality improvement during glass production, and overall automation of processes.

The ﬁrst opening keynote speaker, Bernard Savaëte (left), looked back over the last 25 years of GPD and how the glass industry has developed during this period and expectations for the future.

However, as Bernard Savaëte pointed out, the last 25 years have not been void of mistakes: Underestimating Chinese capacity, overinvestment and overestimation of solar controlled glass capacity needs in Europe, total lack of co-operation and collaboration, a large disparity in quality levels and weak, inefﬁcient R&D; the proverbial outcome being no breakthrough innovations in processing and products. The expectation of Bernard Savaëte for the future are heavily inﬂuenced by macro trends and parallel industries and sectors: global population growth and urbanization, developments in building and construction, diversifying technologies like 3D printing, the continued focus on CO2 emissions, self-driving cars and growing internet applications with new functionalities.

Four expectations for business and processing; 1. Consolidation and restructuring 2. Focus on energy and the environment 3. Changes to melting or even alternative melting processes 4. Recycling flat glass (currently flag shipped by the Netherlands who recycle 88% of flat glass)

Three key expectations for products; 1. Bigger, thinner and more complex 2. Improved durability (reducing breakage, improvement of surface durability)

1992

2017

150 ﬂoat ovens

more than 500 ovens world-wide

25 lines ﬂoat in China

more than 250 lines

60% of production in EU, USA, Japan

less than 20% production in the EU, USA and Japan

4 dominants parties in the market

There are new providers in the marketplace

322 Chinese patents for glass

over 7000 Chinese patents

80 Korean patents

now more than 1000 patents from Korea

50 | Intelligent Glass Solutions | Winter 2017

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MARKET INTELLIGENCE: TRANSPARENT FACADES

3. Focus on comfort (thermal comfort, visual comfort in conjunction with energy management. Smart and power windows are a pertinent example of this marriage of thoughts)

Two main expectations for fabricators; 1. Complexity of demand 2. Global competition Expectations with regard to the market include growth in China, India, Africa, Asia and South America. In terms of demand, trends in development are forecast in renewable energy efficient glass, renovation of existing buildings (especially in low growing regions) and glass recycling. Moreover, the expectation is that there will only be 4 to 5 new float ovens per year to keep track of population growth. Bernard Savaëte touched on the area of industry investment and its future needs, including research and development (especially in cooperation with universities and other industries), marketing, glass for integrated energy generation, logistics and transport, energy efficient production and the development of an improved and efficient melting process. Opening keynote speaker Prof. Pen Shou, from Bengbu design & research Institute focused on trends and developments in the Chinese market. This area is relevant to today’s glass industry, with the largest market share in the world and the highest number of patents. Most notably, China produced 38.7 million tons in 2016, which was more than 60% of the total global glass production.

People who have had great inﬂuence over the last 25 years in the industry Russ Ebeid

Alev Yaraman

Eric Trösch

Cho Tak Wong

Jacques Scheuten

Luc Willame

Peter Lisec

Roger O’Shaughnessy

James O’Callaghan

George Hesselbach

Peng Shou

Flat glass production between 2000 and 2016 in China (in 1000 tonnes)

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Winter 2017 | Intelligent Glass Solutions | 51 autumn 2017 | intelligent glass solutions | 51

MARKET INTELLIGENCE: TRANSPARENT FACADES

China is currently a world leader in development, particularly in glass production with the ability to produce thicknesses of 0.15 mm to 25 mm, the quality that clients require for display glass, solar panels and the automotive industry. 1200 ton ovens cater to the market representing the largest daily production capacity in the world. In comparison, within the EU, a 1000 tons/day capacity production plant is in the works in Poland. As we stand today, more than 80 float ovens have been built using Chinese technology; this production quality has to some extent, been extracted and made its way to international markets and assimilated globally. New melting processes have also led to energy savings of up to 30%, paving the way forward for energy efficiency in the glass industry. China is also at the forefront of glass processing machinery and has a large stake in various process industries where 1.6 billion m² of laminated, coated and insulating glass is produced. ‘Business is booming’ in relatively new fields, including: renewable energy, architectural design, the automotive industry, aircraft construction, deep-sea research and ultrathin glass of 0.10 mm for displays and touch screens for smartphones. The Chinese industry has incorporated development strategies to further the market for these applications that are trending towards very thin glass. A strong focus has been placed on cooperation with other industries

No.

Province

Numbers of furnace (set)

Melting capacity (t/d)

Lines ratio (%)

Hebei

34120

24.80

23.47

Guangdong

15450

10.16

10.63

Shandong

10470

8.54

7.20

Hubei

9600

5.69

6.60

Liaoning

8900

5.28

6.12

Jiangsu

7760

5.69

5.34

Anhui

7000

4.47

4.81

Sichuan

6900

3.66

4.75

Fujian

6830

4.47

4.70

Tianjin

5800

3.25

3.99

Zhejiang

5450

4.07

3.75

Shaanxi

3000

2.03

2.06

Henan

2870

2.85

1.97

Hunan

2700

2.03

1.86

Chongqing

2350

1.63

1.62

Shanxi

2300

1.63

1.58

Yunnan

2000

1.63

1.38

Xinjiang

2000

1.63

1.38

Hainan

1800

1.22

1.24

Guizhou

1600

0.81

1.10

Jiangxi

1500

1.22

1.03

Jilin

1200

0.81

0.83

Neimeng

1000

0.81

0.69

Gansu

1000

0.41

0.69

Heilongjiang

600

0.41

Ningxia

600

0.41

Qinghai

600

0.41

246

145400

100.00

Total

Ratio of melting capacity(%)

Flat glass production in China in 2016

Thin ﬁlm cells of ﬂexible glass(above). Flexible display glass (right)

52 | Intelligent Glass Solutions | Winter 2017

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MARKET INTELLIGENCE: TRANSPARENT FACADES

for solar energy, displays, smart phones and automobiles. It is believed that glass can be a modern multi-functional material, throwing caution to the old adage that glass is primarily purposed for construction. Further technology can be commercialised in a growing private market in China. In addition to the keynote addresses and 2 full days of scheduled presentations, guests were also given the opportunity to network through a new initiative and smart tool called “The Meeting Manager’, allowing them to make appointments with other participants. As covered extensively by the press, Dow Chemical and Corning’s long term partnership (since 1994) under the name Dow Corning is almost at an end. From November 2017, under the directorship of Jean-Paul Hautekeer (Global Strategic Market Director), it will be known as DowSil; building, construction and the product portfolio will be marketed under the name Dowsil. Since the first structural glazing project was realized in 1971, 46 years of experience and testing have always accompanied projectcalculations for sealant dimensions, account tests, with new materials and associated best practices are all needed for sustainable structural glazing. The changing market will require necessary developments, speeding up processes and more organic hybrid solutions, a prime example being liquid crystal switchable glass solutions. Corning received international recognition for their youtube video “A day made of glass” where exciting new technologies and innovations were exhibited in the field of smart and display glass. In conversation with Michel Prassas (Corning’s Director for new business in France) he confirms that Corning has focused on developing smart, powerful display glass, and furthered their efforts towards digitization. In addition a joint venture with Saint Gobain with production based in China, has begun, targeting automotive glass, accentuating light weight, ultra-thin glass that will benefit emissions and heat management in cars. The movement towards ultra-thin, energy generating glass for windows with large display applications looks unstoppable. It is not beyond the imagination that future homes will be equipped with ultra-thin glass,

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replacing conventional wallpaper and walls, allowing digital displays and ‘in-glass’ wall-towall televisions. You will be able to wake up to a beautiful sunset, a stunning beach setting or peaceful rippling stream, previously, winter in Europe never seemed so appealing. At the GPD, Merck showed some impressive technology that is pushing the current boundaries of switchable glass based on their years of experience with plasma screen systems.

At the GPD, Merck showed some impressive technology that is pushing the current boundaries of switchable glass based on their years of experience with plasma screen systems. Above: Mock up of switchable glass presented by Merck at GPD.

This technology has jumped leaps and bounds from the old system. Switchable glass has traditionally been based on electrochromics or gas chrome, which has been applied to large scale projects. While it is a formidable technology, it was previously disadvantaged because it had to be turned on using solar control, it previously came in just a single colour (blue) and it previously took up to 20 minutes for full switching and peak performance. The system introduced by Merck switches the plasma instantly and can be switched to a diverse range of colours, you choose. In addition to solar controlled technology, there is an existing system for switching to diffused glass, similar to the well kown and popular Priva-lite developed by St.Gobain. The GPD opening day congress was wrapped up by keynote Speaker and respected Dutch architect Stephanie Akkaoui Hughes who provided an engaging presentation. Stephanie founded Amsterdam based architects AKKA after working 5 years for the renowned Rem Koolhaas architect ﬁrm.

Winter 2017 | Intelligent Glass Solutions | 53

MARKET INTELLIGENCE: TRANSPARENT FACADES

Stephanie is now an in-demand speaker; notable appearances include a seminar at TEDx focused on her book ‘Architecting Interaction’, delving into her philosophy regarding architecture and urban development. On July 29th 2017 the financial daily newspaper (Netherlands) published an interview that elaborated on infrastructure, traffic management projects in the city of Rotterdam and ‘mobility of the future’. As outlined by Stephanie, Rotterdam does not need new roads, but must make better use of the existing road network. This notion is carried throughout her philosophy; architecture is not an art form but a service, instead of imposing the architects ideas on a client, architects need to be more aware of the client’s needs. Architects are not only hired to design buildings, they should exist to increase productivity and serve the needs of those working inside of a building. The enduser is thus the frame of reference for future design, innovation, and interaction. This year’s GPD event drew significantly more participants than previous years, with over 600 guests present on the occasion of the Jubilee. Attending the 25th Anniversary of GPD was well worth the trip to Tampere in Finland. Exciting new projects, technologies and start-ups (many arising through universities) assured the glass industry that there is a bright future and glass in architecture remains a focal topic and as strong a passion as ever.

Stephanie Akkaou Hughes: Architects are not only hired to design buildings, they should exist to increase productivity and serve the needs of those working inside of a building. The end-user is thus the frame of reference for future design, innovation, and interaction.

Stephanie Akkaou Hughes

Paul Bastianen If you would like to comment on this column or on other topics, I would be pleased to hear from you by phone +31 643 888 728 or email p.bastianen@planet.nl

This year’s GPD event drew signiﬁcantly more participants than previous years, with over 600 guests present on the occasion of the Jubilee.

54 | Intelligent Glass Solutions | Winter 2017

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THE GLASS SUPPER OVER 7 YEARS

The Glass Supper over 7 years:

A never ending story The IGS Column of Paul Bastianen UI %FDFN CFS

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2012 Where will the architectural glass industry be in 100 years time? 2013 High performance faĂ§ades, what does this mean? 2014 Battersea Power Station featuring the â&#x20AC;&#x153;Best of Britishâ&#x20AC;? 2015 Connections â&#x20AC;&#x201C; Making friends in high places 2016 Pollution- the architectâ&#x20AC;&#x2122;s role 2017

People-centric; Buildings designed with people in mind

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The Glass Supper

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By sheer coincidence this yearâ&#x20AC;&#x2122;s Glass Supper in London is the seventh time the event is taking place and itâ&#x20AC;&#x2122;s happening on the 7th December, continuing the line of successful events. A bud that started as a simple idea for an intimate gathering of knowledgeable individuals who share a burning passion for glass architecture has grown and ďŹ&#x201A;owered into an event with over 400 star-studded guests who can legitimately be called Spearheads of the architectural glass and faĂ§ade industry. On 7th December 2017, guests from 28 countries, including Emirates, China, Russia, Turkey, Canada, Australia, Hong Kong, India, Saudi Arabia, South Korea and the European contingency will come face to face inside the Tanks at the New Tate Modern in London to join a one-day experience that facilitates open, leadership level discussion, addressing high performing systems and solutions in todayâ&#x20AC;&#x2122;s global architectural glass construction industry. The event historically attracts architects, engineering consultants, material specialists, contractors, real estate and academia with a very high number of Founding Partners, CEOâ&#x20AC;&#x2122;s, Managing Directors, Business developers and Consultants; facilitating the perfect environment for top line networking in what has always been a ďŹ ercely competitive industry. The Glass Supper is not all business though, it offers guests a great evening to wind down and reďŹ&#x201A;ect on the past yearâ&#x20AC;&#x2122;s hard work, whilst at the same time making plans for the year ahead.

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Historic overview i 2011 Glass Supper: Complex Geometries The inaugural Glass Supper was held on Thursday, 8th December 2011 in The Radisson Edwardian Bloomsbury Street Hotel in the very heart of London. The aim was to bring together around 60-70 people, although as with most years, visitor numbers exceeded expectations with 117 happy guests. The event was designed as an intimate gathering of a few visionary individuals noted for their passion when it comes to high performance architectural glass. The day was focused on topical discussions and debates based on disruptive technologies that would shake up the industry in the future, and show signs indicative of the way the industry intends to move collectively forward. The Glass Supper Speakers have always been chosen with great consideration; representing the best and brightest minds in each ďŹ eld. In 2011, the line-up of speakers included: Henry Bardsley, Dr Mikkel Kragh, Bernhard Rudolf, Dr Werner Wagner, Paul Savidge, Dirk Schulte, Jeppe Hundevad, Johann Sischka, Marie Elliott and Graham Dodd who shared the podium and addressed the trending topics within the glass faĂ§ade and architecture industries. UI %FDFNCFS t 5IF 3BEJTTPO &EXBSEJBO #MPPNTCVSZ 4USFFU )PUFM )PMCPSO -POEPO

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THE GLASS SUPPER OVER 7 YEARS

In 2012, the Glass Supper was moved to one of the most iconic and recognisable glass buildings in London: City Hall, Queens Walk, designed by Foster & Partners. The building was and is still the residence of The Mayor of London It was in this year that 150 guests and his local Government. Gove broke and shared the proverbial Glass Supper bread. Architects have made their love for glass clear. It is, to them, the material of choice. But…far from this nostalgic notion, the understanding at that time, was that architectural glass had lost its glamour and despite their love for this sexy see-through material, less glass was being specified in buildings by certain architects, most notably Ken Shuttleworth (MAKE). The event began with an afternoon of open discussion (bull fighting) taking a long hard look at the architectural glass industry and all its imperfections. Guests looked at the ancient Vitruvian Virtues of firmness, usefulness and delight and discussed how they influenced building design and human lifestyles in the modern day. The focus was on the future of glass in the architectural realm: what should the glass industry really be doing, future contributions to designing complex cities and the on-going symbiotic relationship between architecture and glass. 'SJEBZ UI %FDFNCFS t $JUZ )BMM -POEPO

Where will the architectural glass industry be in 100 years time?

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Speakers at the Glass Supper 2012: • Albert Dubler, President of UIA, Opening Speaker. Topic: The thing about glass • Tristram Carfrae, Arup Fellow & Chairman. Topic: A Global overview, architectural trends around the world and what the glass industry should really be doing • Ian Ritchie, Ian Ritchie Architects. Topic: Looking at glass architecture through the eyes of Vitruvius • Hugh Dutton, Principal HAD Paris. Topic: Life in the world to come- likely trends in the complexity of designing future cities • Ken Shutleworth, Principal Make Architects. Topic : Throwing stones. Straight talk from a straight talker on the symbiotic relationship with glass and how things have changed. • Graham Fairley, Chairman of the SFE Topic: The importance of widening membership of the SFE to ensure façade engineers have a recognised mark of approval –a brand

2013 Glass Supper: High performance façades, what does this mean? 2013 saw the event move to The London Hilton in Canary Wharf where presenters from two uncompromising yet inextricably linked sectors (architects and glass people) convened and provided anecdotal evidence of how to use new intelligent glass solutions to their full potential in a clear, unrestricted open-air ope energized debate. The event focused on high performance facades and the encompassing issues including the use of daylight, sun control, ventilation and cooling systems, reducing the use of heating, enhancing occupant health and comfort and the on-going debate on sustainability, the environment and climate control in façade design. In 2013, the International Award for Façade Engineering Excellence was introduced at the Glass Supper with the inaugural award won by AEDAS for the façade engineering work on Al Bahr Towers in Abu Dhabi. Wednesday 20th November at The London Hilton Canary Wharf

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Speakers at the Glass Supper 2013: • Stephen R. Hodder, RIBA President and Chairman at Hodder + Partners. Opening Speaker • Mikkel Kragh, Dow Corning. Topic: The Value of Design • Bjorn Sanden, then DuPont. Topic : Global megatrends impacting the market • Stacy Eisenberg, Atelier Jean Nouvel. Topic: Presentation of 4 recent projects by Atelier Jean Nouvel with an emphasis on the Envelope • Hani Rashid, Asymptote Architects. Topic: Glass and the transparency as the most important weapon in the Asymptote designs. • Scott Thomsen, Guardian Industries. Topic: Glass awakening • James O’Callaghan, EOC. Topic: The evolution of structural glass over the last twenty years. • David Richards, Arup. Topic: High performance from urban scale to buildings. • Professor David Fisher, Dynamic Architecture. Topic: Transparency of glass takes barriers away between humans and nature.

2014 Glass Supper: “Best of British” 2014

2012 Glass Supper: Where will the architectural glass industry be in 100 years time?

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• Arieta Attali, Professor at GSAPP, Columbia University, NYC. Topic: Reﬂected transparency • Danny Lane, an artist/ sculpture in glass. Topic: Taking the material to extreme limits- Sculpting in glass

56 | Intelligent Glass Solutions | Winter 2017

GLASS SUPPER EVENT PARTNERS

The 4th “Glass Supper” is presented by Intelligent Glass Solutions

In 2014, the Glass Supper was held in the historic and quintessentially English Merchant Taylor’s Hall, a space most notably associated with the London Stock Exchange. With its theme, the “Best of British”, the Glass Supper afﬁrmed the engineering artistry that made England the most exciting country under the sun

THE GLASS SUPPER OVER 7 YEARS

and in London, most notably, a city which is the envy of the world. The event recognised the best British architects, the best construction projects, the best glass suppliers, the best innovators, the best glass solutions, celebrating and paying homage to this eclectic country and its architecture. Most appropriate at the time, a large emphasis was placed on the development of Battersea Power Station, a historic landmark in London described as the â&#x20AC;&#x153;jewel in the crownâ&#x20AC;? of construction projects in the UK by the Mayor of London who at the time was the enigmatic Boris Johnson. To date, work continues on transforming this grade 2 listed building into a working and living space for future generations.

Speakers at the Glass Supper 2014 Speakers were British architects directly involved in the design and construction of Battersea Power Station development: â&#x20AC;˘ Ian Simpson, Ian Simpson Architects â&#x20AC;˘ Philip Marsh, dRMM â&#x20AC;˘ Jim Eyre, Wilkinson Eyre Architects â&#x20AC;˘ Grant Brooker, Foster and Partners

Following the success of the inaugural SFE Awards at the Glass Supper 2013, the SFE called for entries for the FaĂ§ade 2015 competition. The second international SFE awards was designed to recognise, promote and reward excellence in increasingly important elements of building design and construction. RIBA President Jane Duncan, presented prizes for three categories: the best of New Builds, Refurbishments and for Outstanding FaĂ§ade Innovation.

And the winners were: â&#x20AC;˘ Flynn Group from Canada for the FaĂ§ade of the Year 2015 in the New Build category for the Ryerson Student Learning Centre in Toronto; â&#x20AC;˘ Arup, the FaĂ§ade of the Year 2015 in the Refurbishment category, for the Guys Hospital Tower â&#x20AC;˘ Arup & Bellapart from Spain jointly awarded the Outstanding FaĂ§ade Innovation 2015 category for the Bombay Sapphire Distillery.

Speakers at the Glass Supper 2015 â&#x20AC;˘ Amanda Reynolds: Moderator, Architect and Urban Designer.

2015 Glass Supper: â&#x20AC;&#x153;The Virtue of Delightâ&#x20AC;? In 2015 the Glass Supper was held high up on the 37th ďŹ&#x201A;oor in the sky garden of 20 Fenchurch Street, a building otherwise known as The Walkie2015 Talkie. Designed by architect Rafael Vinoly, the building quickly became an unmistakeable feature fe in the London skyline. It was loved and hated in equal measure, with urban myths seeping through the grapevine as to its power to melt cars and fry eggs on the adjoining pavement due to the reďŹ&#x201A;ection of the sun from the building. Subsequently this gave rise to a few comical nicknames, including the â&#x20AC;&#x2DC;Fry-Scraperâ&#x20AC;&#x2122; and â&#x20AC;&#x2DC;Walkie-Scorchieâ&#x20AC;&#x2122;. The speakers on this occasion were all female and reďŹ&#x201A;ected on various aspects of delight (the third Vitruvian virtue) in their presentations; what it means to them and how they incorporate delight into their day to day work. Is delight an important virtue in buildings today when we are faced with incredibly urgent energy efďŹ ciency issues and pressing climate change challenges? Should delight in architecture be sacriďŹ ced for more practical building energy management and/or safety and security solutions in order to satisfy the needs of today? The answers to these and the most critical industry issues were debated and answered in this historic edition of the Supper. 2015 was a special year as the Glass Supper celebrated women and their contribution to the glass industry. The event operated a no men on stage policy which we were told was the ďŹ rst time in this industry anything like this had taken place. Making friends in high places

The Virtue of

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â&#x20AC;˘ Jane Duncan (the newly appointed President of RIBA). Jane presented an engaging discussion calling for women to smash through the glass ceiling. â&#x20AC;&#x2DC;â&#x20AC;&#x2122;We are moving towards the time when people are hired because they are talented and good enough for the job. A change is a-coming.â&#x20AC;? â&#x20AC;˘ Megan Beth Royston, Principal at Adamson Associates â&#x20AC;˘ Eva Jiricna, Eva Jiricna Architects â&#x20AC;˘ Karen Cook, Founding Partner at PLP Architecture â&#x20AC;˘ Nicole Dosso, Director at SOM â&#x20AC;˘ Eilis McShane, BrookďŹ eld Multiplex â&#x20AC;˘ Becci Taylor, Associate Director within Building Group at Arup

2016 Glass Supper: â&#x20AC;&#x153;Pollution- the architectâ&#x20AC;&#x2122;s roleâ&#x20AC;? In 2016, the Glass Supper was held at the sophisticated Gibson Hall, a converted banking hall in the city 2016 of London. As advertised the event focused on pollution and the roles and responsibilities of architects, engineers and faĂ§ade des designers. From innovative technologies, designs and research and development, the speakers provided meaningful contributions to tackling this global issue. How could we mention the year 2016 without Brexit? We could not, and accordingly this yearâ&#x20AC;&#x2122;s event focused on the pros and cons of Brexit for the architectural glass economy from the UK point of view and also from the wider European Communityâ&#x20AC;&#x2122;s perspective. (JCTPO )BMM #JTIPQTHBUF -POEPO t 5IVSTEBZ TU %FDFNCFS

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THE GLASS SUPPER OVER 7 YEARS

The Façade of the Year Awards 2016, established by the Society of Façade Engineering (SFE) was presented by Chris Macey, Chair of the Society of Façade Engineering Judging Panel. 1. Façade of the Year in the Refurbishment category went to Arup for 10 New Burlington Street, London. 2. The Outstanding Façade Innovation category went to TU Delft & ABT Consulting Engineers for the Crystal Houses, Amsterdam. 3. The Façade of the Year in the New Build category went to Buro Happold for their work on Columbia University, Vagelos Education Centre, New York; to Octatube for the Glass Entrance Building of the Van Gogh Museum and to Volker Gienke & Company for Great Amber, Liepaja, Latvia.

Speakers at the Glass Supper 2016 • Miriam White, Architect, Project Manager and CoFounding Partner of CDLP Developments, and the Glass Supper 2016 Moderator • Annie Hampson, City of London Corporation’s Chief Planning Ofﬁcer and Development Director and the Opening Speaker • Emily Wallace, CEO, GK Strategy. Topic: Addressing the Audience on the Post Brexit Economy: Exiting Europe, How will Brexit affect the glass and façade sector of industry? • Bertrand Cazes, Glass for Europe. Topic: The role of the glass industry in tackling air pollution • Ann-Marie Aguilar and Alistair Law, Arup. Topic: Healthy buildings and the Well Building Standard • Lars Anders, Priedemann Facades. Topic: Clever Building Skins to reduce Pollution • Sandeep Kashyap, Kuraray/ Trosifol. Topic: External noise pollution stiﬂes internal productivity • Alan McLenaghan, Sage Glass. Topic: Adaptive Facades can positively impact the Health & Well being of Buildings

2017 Glass Supper: “People-Centric: Buildings Designed with People in Mind” inside “The Tanks” at the New Tate T Modern December Thursday 7th Decemb

This Year’s Glass Supper (2017)

Over 400 guests from all over the world are committed to gathering face to face People-centric inside the Tanks in the New Tate Modern in London to join a one day experience that facilitates open, leadership level di discussion, i addressing dd high performing systems and solutions in today’s global architectural glass and facade industry. Coming together under the theme, People-centric, buildings designed with people in mind, the Glass Supper 2017 will help architects and glass industry decision makers keep humans at the centre of future structural building design, forming a template that will stimulate creativity and & The Society of Facade Engineering gineering Awards

Buildings designed with people in mind EVENT EVENT PARTNERS: PARTNERS:

The Glass Supper 2016 is presented by Intelligent Glass Solutions

58 | Intelligent Glass Solutions | Winter 2017

strengthen the architectural framework of life in the world to come. From past to present Glass Supper events, two themes stand out in their ambitiousness and relevanc in today’s glass and architecture landscape. Where will the architectural glass industry be in 100 years (from the 2012 event) and this year’s theme of focusing on the occupants inside of buildings right from the outset, in the design. The two are inextricably linked as the future of architecture is pushing towards functionality in building design, with focus on how designs affect the inhabitants of a space as opposed to just the external aesthetics of a building. Arguably, it is difficult to predict trends 5 – 10 years in advance, let alone 100 years. Flying cars, science fiction buildings and homes, and robots fill our imaginations with possibilities of an exciting future. What contribution does the Glass and architecture industry play in this revolution? Apparently glass DOES NOT do the things architects require, technology does not move fast enough, there is a lack of innovation and our market share will continue to shrink. As mentioned earlier the strapline from 2012 “where will the glass industry be in 100 years’ time?” came from the lips of internationally renowned architect Ken Shuttleworth (part of the Foster+Partners design team for the Gherkin and Glass Supper venue City Hall, amongst others). His words verbatim; where does the glass industry think it will be in 100 years’ time, do they actually think that far ahead? There is certainly a call for the glass industry to move faster and bring innovation and developments to the field quicker. For years commentaries from within the glass industry itself have admitted that new products and substantial, meaningful innovation come around every 15 years, which is far too long. This year’s Glass Supper theme is particularly relevant to this issue, as the need to focus on the inhabitants of a building and their shared experiences within an architectural space is pushing the boundaries of glass technology required to enhance the user’s functioning and performance. The old adage of architects designing from the outside with the people who work or live inside of secondary importance is out the window (excuse the pun) and a new age of human-centric design is here. The study into the so-called sick building syndrome is a prime example of technology responding to people’s needs. Planned Façade designs, with the use of natural light can lead to upwards of 15% productivity in a work place. In the future, 70% of the world’s population will live in metropolitan and built up urban environments where building designs and technology will play an important role. Working, leisure, shopping and living spaces will need to accommodate growing populations and contribute to enhancing productivity, user experience and lifestyles. The foremost issue in the glass industry is the need to contribute meaningful innovation, technology and skilled minds to this future.

THE GLASS SUPPER OVER 7 YEARS

The Glass Supper 2017 has created a platform from which to initiate leadership level discussions on this topic and drive innovation in the architectural glass sector. It is a place to meet top line industry people, listen to the greatest minds of our time and build your business network.

Speakers at the Glass Supper 2017 • Ben Derbyshire president of the RIBA will open the event • Stephanie Akkaoui Hughes, AKKA architects. Topic: buildings designed with people in mind • Kevin Hyde, Integral Group Founder and CEO. Topic: well building certiﬁcation and the brightness of creative stimulation • James Carpenter CEO Carpenter design. Topic: natural daylighting with glass in buildings – light from light • Prof. Stefan Behling and James O’Callaghan (2 award winning speakers) • Rachel Haugh and Christian Male. Topic: a comprehensive look at one Blackfriars London, now is tomorrow.

Paul Bastianen If you would like to comment on this article or on other topics, I would be pleased to hear from you by phone +31 643 888 728 or email p.bastianen@planet.nl

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ANNIVERSARY

Curious? The Trade Show. Window. Door. Façade. Nuremberg, 21–24.3.2018 For more information please contact: Overseas Trade Show Agencies Ltd. T + 44 (0) 20.7886 3102 otsa@otsa.net

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Winter 2017 | Intelligent Glass Solutions | 59

Celebrating 25 years of GPD in Finand

Shaping ultra-thin glass

Shaping ultra -thin glass

Sophie Pennetier Mark Bowers Guillaume Evain Arup BIG Architects KEYWORDS Ultra-thin glass • Cold bent glass • Sculpture

Ultra Thin glass – Arup, BIG Architects Abstract Ultra-thin glass is neither a new product nor new to the building environment. It is yet very little utilized in translucent facades for stiffness, detailing and cost reasons. This paper describes the elaboration of a cold bent ultra-thin glass sculpture, from concept to procurement, with explorations worth the eye of the façade designers. The design tools, FE analysis and testing procedure and fabrication of the glass elements are documented.

1. Introduction In the building environment, transportation, household or artistic applications, glass is generally formed by slumping process, at temperatures exceeding 600 ºC. The works described herein are based on the elastic deformation of the glass, which means that the glass is shaped without the use of heat but only by application of a sustained loading. This engages the glass structurally, not only as a rigid body transferring load like in the audacious Serres de la Villette by Peter Rice and RFR but where the glass compounds are subject to permanent internal bending forces like in other project RFR projects, such as the Avignon and Strasbourg railway stations. The present work, of a much smaller scale, is a sculpture made of cold bent 200 μm glass strips, where the stability and the rigidity of the system is ensured by the internal bending forces of the glass, locked into the strips connected to one another. The sculpture measures 750mm by 750mm on plan and 700mm in height. This project demonstrates how an iterative analysis of the geometry and the internal forces can result into a rigid free form system, a process that is scalable to the built environment. The use of thin glass in the built environment has many advantages. A stiff and thin glass façade system allows for the reduction of the glass weight supported by the superstructure, impacting transportation costs and energy demands as a result. The durability of glass in a chemical or corrosive environment and to UV is an asset, it is scratch resistant and hermetic, compared to other thin materials such as polycarbonate or ETFE, and ultimately the optical clarity of the glass is unequaled. Until now, thin glass products such as Corning Gorilla and Willow glass are used in the building environment

60 | Intelligent Glass Solutions | Winter 2017

within a laminate compound, mainly for interior ﬂat applications such as wall cladding (Corning Inc, 2016). This article presents the fundamentals of glass cold bending, the properties of the thin glass product used for the project, the elaboration of the geometry, the structural analysis and the fabrication.

2. Cold bent glass Cold bending a glass element consists of deforming it elastically, without the use of heat. Maintaining the bending force is required to keep the curvature of the glass element. The geometry resulting from the elastic deformation of flat elements is called a developable surface. This requires no distortion of the original flat element, as discussed in further detail in chapter 4. Cold bending is particularly interesting in the built environment for the reason that it does not require any heating process. The bending process can occur in factory or on site, at virtually at any ambient temperature. The façades of several architectural projects comport cold bent glass panels, such as the Avignon train station in France or the IAC Headquarters in New York (respectively Figure 1 and Figure 2). For these two projects, glass sheets were assembled in Insulated Glass Units (IGU) and the limiting component wasn’t the glass itself but the shear of the primary seal of the IGU. This limitation lead to larger curvature radii than the one the glass sheets alone could sustain. Here the geometry allows to keep each strip in place and the structure stable only hanks to the connection to the adjacent glass pieces. Glass warm bending – also called two step bending, coldlamination bending, lamination bending – consists of piling up sheets of glass and interlayer(s), bending the stack onto a support jig and then laminating it in autoclave. When the initial bending force is removed and the laminate removed from the jig, the shear in the interlayer prevents the assembly to completely flatten. The use of the term warm for this fabrication process derives from the fact that the lamination process requires to heat up the compound to ensure the adhesion of the interlayer to the glass. The lamination temperature, which depends on the interlayer material and pressure is approximately 80 to 140 ºC which is well below the softening temperature of glass, which exceeds 600 ºC.

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Shaping ultra-thin glass

Celebrating 25 years of GPD in Finand

Figure 1,2,3 – Cold bent glass architectural projects precedents (left to right) : Strasbourg Railway station (2011, AREP+Dutilleul), IAC Headquarters (2007, Gehry architects), Strasbourg Railway station (2007, AREP+Dutilleul)

Figure 4,5,6 – Left to right: Corning proprietary fusion-draw process, Willow pattern and Willow glass

Given the relative softness of certain interlayers, the glass laminate may partially spring back. (Knippers, Filduth, Badassini, Pennetier, 2014) propose a time history study of warm bent laminates. The glass panels of the Strasbourg train station have been curved using this process (Figure 3).

3 Ultra-thin glass Architectural glass sheets in facades range in thicknesses between 2 and 22 mm. Thin glass refers to 2 to 6mm thickness and ultra-thin is proposed for smaller thicknesses, from of 25 μm to 2mm excluded. Whereas most of the architectural glass for facades is soda-lime glass produced on a float line, thinner glass products such as Corning’s Gorilla Glass and Willow Glass and AGC’s Leoflex have a different chemical composition and different fabrication process. Gorilla glass is composed of aluminosilicate. It is produced in thickness ranging from 0.2 to 0.7mm by a proprietary fusion-draw process. Gorilla is then chemically tempered in potassium chloride, which provides a surface compression stress preventing crack propagation. Willow glass, used for the project discussed herein, is an alkali-free boroaluminosilicate glass (Corning Inc, 2016). It is fabricated by a proprietary overflow process (Corning Inc, 2016). In this process, the glass in fusion overflow out of a gutter on both sides down and fuses at the bottom point of the gutter (see Figure 4). Unlike Gorilla glass, Willow glass is not chemically tem-

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pered and present a breakage pattern similar to the one of annealed glass, shattering in long thin pieces. Willow glass is named after the shape of the overﬂow used during the fabrication Willow glass is produced in sheets up to 1100 x 1200mm or spools of 1300mm wide, 300 meter long. The minimum bend radius, depending on handling and surface weathering, is 90mm for the 100 μm nominal thickness and 180mm for the 200 μm nominal thickness (Corning Inc, 2016). Combining these bending radii to the bending charts provided my Corning (Corning inc, 2016) a design value of 40 MPa was extrapolated and retained for the design of the sculpture. In the built environment, material reduction factors should be used, concomitantly with reduction factors associated with (for example but not limited to) shape, size, load duration.

Figure 7 – Bending stress of Willow glass

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Shaping ultra-thin glass

Figure 8 – Trims of developable surfaces

4 Geometry

1. Helicoidal curves

2. Curve Set 1

3. Cone Set 1

4. Cone Set 2

5. Intersection Cone Sets 1 and 2

6. Cone Sets Trimming

The deformation of inextensible flat sheets results in a developable surface. It is a specific case of ruled surface, which does not only apply to inextensible materials. For example, a hyperbolic paraboloid is a ruled surface which can be built from the translation in space of straight lines, it can be built with extensible nylon fabric but not from paper. Developable surfaces comprise of cylinders, cones and tangent surfaces of spaces curves (Pottman and al) as shown in Figure 8. Conical shapes are ordinarily described by a planar curve and apex point. In the context of this sculpture, we used a variation of conical shapes defined by a space curve and apex point for each of the elements constituent of the geometry. Figure 9 illustrates each step through the generation of the geometry for this project. At first, a set of helicoidal curves were created and distorted smoothly to create desired guide curves (Curve Set 1). The resulting curves are free form and do not comply with any geometrical rule, apart from the fact that they need to not overlap. A first set of cones (Cone Set 1) was generated from each curve to an apex point P1 placed within the helicoidal set of curves (Curved Set 1). A second set of cones (Cone Set 2) was generated from each curve to an apex point P2 located above P1 so that every adjacent surface intersects each other. The Curve set 2 is defined by the intersection of the two sets of cones. Lastly, the two cone sets were trimmed by the Curve Set 2, creating the final developable surfaces used for the sculpture. A parametric model allowed the fine tuning of the geometry in order to control the local radius of curvature.

5 Analysis

7. Final geometry excerpt

8. Final geometry

Figure 9 – Geometric principles

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This project being a sculpture, it was at ﬁrstly analyzed to sustain gravitational and bending forces. An iterative process involving the round trip between maximum bending stresses assessment and the geometry adjustment was performed in a 3D modeling software packages (Rhino and Grasshopper). Since each strip is in

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Shaping ultra-thin glass

Celebrating 25 years of GPD in Finand

pure bending, the principal curvature and bending stress can be derived from Eq. 1 and Eq. 2 below. M = EI/R (Eq.1) m = Et/2R (Eq.2) With E : Young’s modulus of elasticity (N/mm2) I : Moment of inertia (mm4) R : Curvature radius (mm) t: Glass thickness (mm) Figure 10 shows a mapping of the relative principal curvature along one strip of glass. When required, the construction points and generative curves of the strips geometry were adjusted in order to maintain a maximum stress of 35 MPa. This value, which is smaller than the allowable stress extrapolated in chapter 3, was arbitrarily set for the first iterative process, allowing additional reserve capacity for the effects gravity loading and potential buckling effects. Ultimately, the FE analysis proved that the effect of gravity was negligible for this specific geometry, scale and glass thickness. After the parametric study has been performed, the strips were flattened and imported into a finite element analysis software (Strand7). For the analysis, a Young’s modulus of elasticity of 75 GPa and a Poisson’s ratio of 0.225 were used. Each strip was composed of approx. 200 plate elements of max. 20mm width. The thickness of the material was 200 μm. The model totaled 2560 plate elements. Each strip was initially flat and tied by links to the nodes of its final position (see Figure 11). A staged non-linear static analysis was then used to deform gradually the strips while the bending stress increase was monitored. Figure 12 shows the analysis steps. The glass strips are imported as flat geometry in the FE Analysis environment and shrink links pull them into position. At the last stage, when the glass strips are cold bent into position, adjacent nodes at the ridges are coupled together by stiff spring links and the load redistribute between the glass elements. The maximum stresses under bending case and after assigning gravity to the structure were below the maximum allowable stresses, with maximum at supports locations.

6 Models For the fabrication, the 3D geometry was flattened and laid out on sheets. Two study models were built prior to the final construction of the sculpture. A desk model and a full-scale model. Figure 13 shows the fabrication steps of a scaled model made of 0.5mm thick PETG plastic strips and assembled by hand with tape. The first plastic scaled model, an assembly 130 x 130 in plan by 100mm high assembly of 20mm large strips, served as communication tool and a first proof of the fabrication sequence. The second full scale model was fabricated with 1mm PETG foils. It was used as a template for the adjustment of the supports and jigs used for the glass sculpture. The

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Figure 10 – Principal curvature mapping (only one strip shown for clarity)

Figure 11 – Links used for imposing displacement on mesh nodes from ﬂat (above) to bent (below)

Figure 12 – Staged analysis

Figure 13 – PETG model fabrication

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Celebrating 25 years of GPD in Finand

Shaping ultra-thin glass

called scribe and break. It is a similar process to standard glass cutting, despite the small thickness of the glass. The scribing is performed by rolling a small diamond wheel on the glass creating a small crack, or vent. Then the sheet of glass is handled by an operator which breaks it at the location of the vent. This process can be used for pieces of a couple millimeter overall size.

8 Conclusion

Figure 14 – PETG model

full scale fabrication sequence was validated with this model. The connection detailing and assembly are not discussed herein.

7 Glass cutting process The glass elements were provided and CNC cut by Coresix Inc, based in Virginia (USA). The fabrication pictures show in order: unrolling the Willow glass spool, the CNC cutting operation, strips cuts for testing and calibration of the tooling (the microscopic evaluation is not pictured), the breaking out of the ﬁnal pieces, the ﬁnal C shaped pieces and one piece bent by an operator. The cutting process used to cut the glass pieces is

At the time of the publication of this article, the connection detail connecting the glass pieces is still under testing consideration. The design, fabrication and manipulation of the glass elements for the sculpture is a proof of concept of the design process for ultra-thin cold bending to form a small structure with tight curvature for both base flat shape cuts and bending radii. Given its relatively small size and the fact that, as a sculpture, it is not designed to resist climatic or seismic loads, the current design comports assumptions which does not make it directly scalable. The final geometry, the thickness of the glass, the connections between strips and to the ground will need to be re-evaluated. However, it is obvious to the practitioners that the geometrical rules, the geometry to finite element analysis workflow and curved cuts fabrication knowledge capitalized on this project can be used for larger scale. This work was supported by the 2016 Fellowship from the Metropolitan Contemporary Glass Group, Urban Glass Brooklyn and Arup.

Figure 15 – Glass sculpture fabrication images

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Shaping ultra-thin glass

Celebrating 25 years of GPD in Finand

Acknowledgments

References

The authors would like to thank Corning Inc for their technical support and Coresix Inc for providing and cutting the glass. This work is supported by the 2016 Jerry Raphael Fellowship from the Metropolitan Contemporary Glass Group and by Arup IiA# 13618 - Use of thin glass in the built environment.

Corning Inc: Willow Glass Fact Sheet https://www.corning. com/media/worldwide/cdt/documents/ Willow_2014_ fact_sheet.pdf (accessed on 13/02/2017) Corning Willow Glass Laminates website https://www. corning.com/worldwide/en/innovation/corning-emerginginnovations/corning-willow-glass.html (accessed on 13/02/2017) Neugebauer, J.: Determination of Bending Tensile Strength of Thin Glass. Challenging Glass 5 (2016) T. Fildhuth, J. Knippers, F. Bindji-Odzili, N. Baldassini, S. Pennetier: Recovery behaviour of laminated cold bent glass – Numerical analysis and testing. Challenging Glass 4 (2014) H. Pottmann, A. Asperl, M. Hofer, A. Kilian: Architectural Geometry (2007)

Conﬂict of interest statement On behalf of all authors, the corresponding author states that there is no conﬂict of interest.

Figure 16 – Final sculpture rendering image

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Celebrating 25 years of GPD in Finand

Meinhardt Façade Technology

Free-Form Shape Cold-Bent Structural Silicone Glazed Façades - Design Concept and Challenges Benjamin Beer, Technical Director, Meinhardt Façade Technology KEYWORDS Structural Silicone Glazing • Free-Form Cold-Bending • Single Corner Cold-Bending • Warp • Engineering Stress • FE Stress

Abstract Free-form cold-bent structural silicone glazed facades open the door to a new world of options for cost effective two-way curved and free-form shape facades. The design of the primary and secondary seal structural silicones is however a challenge as no design standards are available; even most of the major silicone suppliers currently do not have clear design guidelines for free-form coldbent structural silicone glazed facades. Following up on the previous Glass Performance Days paper by the author with focus on the “single corner cold-bending” [1], this paper focusses on the “free form shape cold-bending” and presents a new design concept for the structural silicone design. In addition, various graphs are shows to provide theoretical background on facade panelisation options, various cold-bending geometries (e.g. spherical, anticlastic and concave/convex free-form), post-cold-bending glass edge rotation and silicone stress models for different cold-bending/edge warp modes.

Introduction After a series of realised projects, the so called “Single Corner Cold-Bending” process (Figure 02) became established within the façade industry to provide better architectural appearance compared to the “Fish Scale” principle (Figure 01). Taking the next step in the coldbending process, the ﬁrst facade using the new “FreeForm Cold-Bending” process is currently being installed in Dubai (Figure 03). Comparing to the panelisation options Fish Scale (outwards, centre-point and inwards) and the option Single Corner Cold-Bending” as explained in Figure 01, the Free-Form Cold-Bending option provides

66 | Intelligent Glass Solutions | Winter 2017

the best approximation to a perfectly curved façade – however with the downside of high complexity in the structural silicone design. When considering the structural silicone design and guidance for a stress based design, both cold-bending processes mentioned above are not covered by national or internal design codes or standards – showing the need for in-depth research and discussions between industry experts. Whilst the single corner cold-bending process was discussed by the author in previous publication [01], [02] including a proposal for a design concept, this paper focusses on a new structural silicone design concept for free-form shape cold-bent facades. This design concept uses a stress approach “FE Stress” (Finite Element Stress) vs. “Engineering Stress”, in which a FE analysis with hyperelastic material constitutive modelling has been implemented for a reference project (Figure 03).

Single Corner Cold-Bending vs. Free-Form Cold-Bending Figure 04 provides an overview of typical cold-bending geometries. The single corner cold-bending is the most common geometry being realised on various projects over the last approximately 10 years. Here, the aluminium framing members are linear and the glass is produced ﬂat. All other cold bending geometries including spherical convex, spherical concave, anticlastic free-form, convex free-form and concave / convex free-form are based on curved framing members. The amount of warp at each corner (P1, P3, P5 and P7), at centre of the edges (P2, P4, P6 and P8) and the relation between the warp data (P1 to P8) deﬁnes the cold-bending geometry. Most cold-bending geometries have an inwards and

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Meinhardt Faรงade Technology

Celebrating 25 years of GPD in Finand

Figure 01: Comparison of Fish Scale and Cold-Bending panelisation options

Figure 02: Single corner cold-bending structural silicone glazed faรงades, Credit Libanais, Beirut

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Figure 03: Free-form shape cold-bent structural silicone glazed faรงades (partially hot bent-glass is used)

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Celebrating 25 years of GPD in Finand

Meinhardt Façade Technology

outwards mode as shown in Figure 05. Swapping in between these two modes can be done by exchanging the warp value of the corner points (P1, P3, P5 and P7) with the warp values of the centre of edges points (P2, P4, P6 and P8). The choice between inwards or outwards mode is usually dictated by the position of the framing members, typically located on the building’s inside.

Cold-Bent Structural Silicone Glazed Facades – Silicone Shear Stresses

Figure 04: Principle overview of the most common cold-bending geometries

Figure 05: Inwards and outwards bending option for spherical concave cold-bending

68 | Intelligent Glass Solutions | Winter 2017

The cold-bending process and resulting curvature causes shear deformations between the various layers of the façade panel assembly. The shear deformation is not constant and varies over the width and height of the panel, maximum values can be expected at the points of greatest shear deﬂections and are deﬁned by the angle of rotation Ð. Figure 06 provides system sketches indicating edge warp and edge rotation for the two key locations: corner and mid-edge. Besides the permanent tensile forces in the structural silicone, the edge rotation angle and resulting permanent shear deformation is one of the key problems when designing cold-bent structural silicone glazed

Figure 06: Comparison of edge warp and edge rotation due to cold-bending

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Meinhardt Façade Technology

facades. This applies to both structural silicone seals (Figure 07): A) Primary Seal - between the IGU inner glass pane and aluminium frame B) Secondary seal - between IGU inner and outer glass pane As per [4] and the corresponding European Technical Approval ETA’s for typical two part structural silicones, the allowable long term silicone stress is only 1/10 of the allowable short term silicone stress. In an effort to reduce the silicone primary seal shear stresses for single corner cold-bent facades and ﬁrstly used for the Credit Libanais project in Beirut [1], the author developed the method “Workshop Cold-Bending & Site Re-Bending”. A comparison of the two cold-bending options for single corner cold-bending is listed below: A) Option A - Site cold-bending:

Celebrating 25 years of GPD in Finand

The glass panel and the framing members are produced flat, the structural silicone between glass panel and framing members is applied in the workshop. Once the silicone is cured, the flat façade panel is transported to site and forced into the cold-bent geometry during installation to the building’s slab edges. B) Option B - Workshop cold-bending and site re-bending: The glass panel and the framing members are produced flat. While still in the workshop, the glass panel and the framing members are forced into the cold-bent geometry using a bending rack. Then the structural silicone between glass and framing member is applied. Once the silicone is cured, the cold-bent façade panel is transported to site in the bending rack. The lifting and installation of the panel requires the panel’s release from the bending rack, for this temporary condition the panel will partially deform back from the cold-bent geometry and silicone shear stresses increase for that moment. The panel fixing to the building’s slab edges will require the site re-coldbending. After that process, the installation is finished and the silicone shear stresses are back to the post-cold-bending normal level. Figure 07 compares the corner shear deformations and provides an overview table for the single corner cold-bending options A and B, as well as for the mode free-form cold-bending. As mentioned above, the single corner cold-bending option B results in lower shear stresses in the primary seal. Due to the pre-curved framing members used for free-form cold-bending, a similar effect with lower shear stresses in the primary seal is achieved. It shall be noted that for all options, the shear stresses in the secondary seal (between inner and outer glass pane) are not reduced as the insulating glass production is usually before façade panel assembly and cold-bending. An insulating glass unit production with application of the secondary seal structural silicone post-cold-bending might be technically feasible, would however require further research and is does not form part of this paper.

Free-Form Cold-Bent Structural Silicone Glazed Facades – Silicone Tensile Stresses Figure 07: Single corner and free-form cold-bending – Mullion, glass and silicone details with shear deformation

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As for the allowable silicone shear stress, also the tensile stress for long term loads can be assumed to 10% of short

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term allowable stress. Due to the elastic cold-bending process and the glass trying to bend back into its original ﬂat position, permanent (long term) tensile stresses act in the silicone. The distribution of the permanent silicone tensile stresses depends on the cold-bending geometry and the method of stress analysis: hand calculations or Finite Element (FE) analysis. Referring to the output of computational FE analysis and stress peaks often encountered in the results graphs, the evaluation requires substantial expertise and engineering judgement. The stress peaks are often localized in small areas and might be “cut-out” to avoid an overly conservative design - considering that these small overstressed areas will

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result in a localised higher elongation, which shall be no problem for the overall system. The concept of corner “cut-out” of local stress peaks was presented for single corner cold-bending in [1]. Figure 08 compares the theoretical stress models with actual models, both for single corner cold-bending and free-form shape cold-bending.

Free-Form Cold-Bent Structural Silicone Glazed Façade – Project Example As mentioned in the introduction, the ﬁrst project using the free-form Cold-Bending process is currently under installation in Dubai (Figure 03). The curved facades use both hot-bent glass and cold-bent glass; the hot-bent glass is used for areas

Figure 09: Free-form cold-bent structural silicone glazed unitized façade panel before glass cold-bending process, gap showing the corner warp

Figure 10: Free-form cold-bent structural silicone glazed unitized façade panel during glass cold-bending process, concave long edges and convex short edges

Figure 08: Silicone tensile stress models for single corner and free-form coldbending

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Figure 11: Free-form cold-bent structural silicone glazed unitized façade panel during glass cold-bending process, concave long edge

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with high curvature where cold-bending limits would have been exceeded. Figure 09 shows the pre-cold-bending status with the open gap (corner warp) between glass and frame. Figures 10 and 11 show photos taken after coldbending and prior to primary seal structural silicone application.

Engineering Approach for the Structural Silicone Design Concept

Figure 12: H-test specimen FE model to derive conversion factor “Engineering Stress” to “FE Stress”

Currently no international code or standard covers the structural silicone design of coldbent structural silicone glazed systems. Guidance on the structural silicone design using FE models is given in [5] and [6], where publication [5] presents the concept of True (FE) Stresses vs. Engineering Stresses and emphasizes the importance of deriving a conversion factor between both stresses (also see item B below). This paper is based on an engineering approach using the following steps: A. Initial simplified assessment of the structural silicone seals assuming flat glass and flat framing (no coldbending) using ETAG 002 “Structural Sealant Glazing Systems Part 1: Supported and Unsupported Systems” [4]. This is for initial guidance only an helps to assess the silicone’s capacity available for additional (coldbending) stresses. B. Set up and analyse a FE model to simulate the ETAG002 [4] H-test model already tested by the silicone supplier as per ETA (European Technical Approval). This model acts as a validation model to derive a conversion factor between the true Finite Element (FE) Stress derived from the FE models, and the Engineering Stress as per the allowable design limit stress stated in the ETA of the silicone supplier. C. Set up and analyse a FE-Model for each free-form shape cold-bent glass panel. The structural models include 3D volume elements of the structural silicone and all loads including long term (e.g. cold-bending) and short term loads (e.g. wind pressure and suction). D. Assessment of the FE-Stress results and conversion from “FE-Stress” to “Engineering Stress”, result overview using the allowance stress approach as per [4]. Local stress peaks might be assessed using the “corner cut-out” method explained in [1].

50 mm length (Figure 12). These dimensions are in line with ETAG ﬁgures [4]. Stresses and strains are derived for this model and compared with the actual test results. This H-test FE model (Figure 12) shall use the same setting (analysis software Marc Mentat 12, setting, FE mesh density, etc.) as the FE models of the complete glass panels being coldbent (Figure 20, 21). All FE models use shell elements for the glass panes, volume elements for the structural silicone sealants and the Neo-Hook material model for the silicones:

Two load cases were set up to derive the conversion factors for a typical 0.14 N/mm2 silicone stress limit (as per silicone supplier’s ETA), and a silicone overstress of 1.0 N/ mm2 (as the engineer’s judgement). See data below: • Load case 84 N tensile load to derive conversion factor for 0.14 N/mm2 silicone stress: Face load on upper steel plate: 84 N / (40 mm x 50 mm) = 0.042 N/mm2 Nominal tension stress in silicone: 84 N / (12 mm x 50 mm) = 0.140 N/mm2 • Load case 600 N tensile load to derive conversion factor for 1.0 N/mm2 silicone stress: Face load on steel plate: 600 N / (40 mm x 50 mm) = 0.3 N/mm² Nominal tension stress in silicone: 600 N / (12 mm x 50 mm) = 1.0 N/mm² The FE results are shown in Figure 13 to 15. Taking the Van Mises stress output of the load case 84 N and 600 N

H-Test Model to Derive Conversion Factor “Engineering Stress” to “Finite Element Stress” The H-test model FE analysis shall use identical boundary conditions as the laboratory tested H-test specimen as per [4]; the steel plate being 40 mm width, 50 mm length, 5 mm thickness and the silicone being 12 mm width, 12 mm height

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Figure 13: H-test specimen FE result for normal tensile stress, load case 84 N, course mesh

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Figure 14: H-test specimen FE model result for equivalent von Mises Stress, load case 84 N, course mesh

models, the following conversion factors “Engineering Stress” to “Finite Element Stress” can be derived: • Load case 84 N (equivalent to 0.14 N/ mm2 Engineering Stress): 3.59 • Load case 600 N (equivalent to 1.0 N/ mm2 Engineering Stress): 3.52 The above factor of 3.52 and 3.59 depends on the FE software, calculation model, mesh density, stress type used and other items. Therefore, the above conversion factor varies from the factor shown in other publications [5]. It shall also be noted that [5] used the First Principle Stress, whereas the above calculations use the Van-Mises Stress. Both stresses can be used and the difference in the conversion factors is almost neglectable (Figure 16).

FE Mesh Density Figure 15: H-test specimen FE result for equivalent von Mises Stress for load case 600 N, course mesh

Figure 16: Conversion Factors for Van-Mises and Frist Principle Stress at 0.14 N/ mm2 and 1.0 N/mm2 Engineering Stress

Figure 17: H-test specimen FE result for equivalent von Mises Stress for load case 600 N, ﬁne mesh

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The above H-Test models (Figure 13 to 15) use an identical FE mesh density as the as the actual models of the complete glass panels (Figure 21). This is important as the conversion factor Engineering Stress to FE Stress from the H-Test model will be used for actual calculations. The mesh density of the H-Test models above might be seen as course and not dense enough. This however should have no effect as the same mesh density is used for the actual calculations of the complete glass panels (Figure 21), nevertheless comparison calculations with higher FE mesh densities were carried out. When comparing the Van Mises stresses of the H-Test model with course mesh (Figure 13 to 15) and the Van Mises stresses of the H-Test model with fine and extra fine mesh (Figure 17 to 19), the difference in maximum Van Mises stress is as follows: • Standard mesh density (course): 3.53 N/mm2 • Fine mesh density: 4.08 N/mm2 • Extra fine mesh density: 4.92 N/mm2 To keep the computing time within reasonable limits, the actual models of the complete glass panels use the standard mesh. As the H-Test model for calculation of the conversion factor uses the same mesh density, this standard mesh will not lead to significant differences in the stress results and is therefore acceptable.

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Full Scale FE Models of Free-Form Cold-Bent Structural Silicone Glazed Panels The FE models are built in two stages; first the structural sealant with an ideal stiff bent frame (zero deflections under all load cases) and second the planar (flat) insulating glass unit. FE contact elements are placed between the insulating glass unit and structural sealant. The modelling and analysis process involves the following steps:

Figure 18: H-test specimen FE result for equivalent von Mises Stress for load case 600 N, ﬁne mesh (ﬁve sections through silicone)

Figure 19: H-test specimen FE result for equivalent von Mises Stress for load case 600 N, extra ﬁne mesh

1. Set up of the initial pre-cold-bending model with curved framing and planar (ﬂat) glass (Figure 20). Generate the FE mesh (Figure 21) with mesh density as per H-test model used to derive the conversion factor “Engineering Stress” to “Finite Element Stress”. 2. The initial model with planar insulating glass is loaded at the edges, the glass is deformed until the edges get in contact with the structural sealant geometry (bent silicon, Figure 22). The contact elements are closed and will be “glued” for the other steps. This step considers that the primary structural silicone is applied after cold-bending of the glass, see also the illustration and table data for freeform cold-bending shown in Figure 07. 3. The edge loads required to achieve contact between the silicone and the curved frame are deleted. All glass elastic cold-bending loads are now transferred via the structural silicone; preventing the glass to bow back into its original ﬂat (planar) geometry.

Figure 20: Example of full scale FE model at pre-cold-bending stage, overall view

Figure 21: Full scale FE model at pre-cold-bending stage, detail

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4. Load the model with the climatic loads (isochronic pressure in cavity) based on air pressure (hPa), temperature change in air cavity (°C) and the height difference (m) between glass manufacturer and site location. 5. Add the wind loads. The process of load application at the edges during step 1 is iterative, the load amount and load spacing must be varied up to the status of continuous contact between the silicone and framing at all locations. Some FE programs allow coloured output plots for contact checks (Figure 23).

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Evaluation of FE Analysis Stress Outputs

Figure 22: Full scale FE model at post-cold-bending stage, detail with deﬂection plot

Figure 23: Full scale FE model, contact check of primary seal structural silicone to frame (yellow: 1 - full contact, blue: 0 - no contact)

Figure 24: FE analysis stress plot of primary seal (Van Mises stress) for load case 1, showing local stress peaks

Figure 25: FE analysis stress plot of primary seal (Van Mises stress) for load case 1, excluding corner cut-out areas

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FE analysis stress outputs for the following load cases (item 1 to 4) and load combinations (item 5) shall be checked to evaluate compliance to allowable stress limits: 1. Dead load - Long term load 2. Post-cold-bending (cold-bending forces released) - Long term load 3. Climate loads (isochronic pressure, summer or winter) - Long term load 4. Wind load (pressure or suction) Short term load 5. Combinations of the above load cases including wind load case – Combination of long and short term loads Item 5 refers to load combinations including short and long term loads. Here the results evaluation is further complicated by the different stress limits for long term loads and short term loads, where the stress limits for long term loads is usually 1/10 of the limit for short term loads. Due to the nature of the cold-bending process reﬂected in the steps during FE analysis, the short term load case 4 (wind load) can only be run in conjunction with the long term load case 2 (cold-bending forces released: post-cold-bending). For this load combination, the FE software provides just one stress plot “merging” the stress results for the long term and short term load case. An “manual” overlay of the short and long term stress data for each FE mesh nodal point can be done, however this complex and time consuming method might not be preferred. Further research will be required to assess the best way how to easily evaluate these load combinations. Looking at the overall stress plot for one glass panel, the evaluation of FE results can differentiate between “Overall”, “Peak” and “Non-Peak” areas. For peak areas, the concept of cutting out stress peaks (Figure 08) can be used to avoid an overly conservative design. The deﬁnition of extent of corner cut-out requires engineering judgement and experience, as a local silicone overstress will be allowed. In the case of the secondary sealant, acting as the edge seal of insulating glass unit, the

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local overstress might lead to a locally reduced air tightness of the edge seal. A typical corner area with stress peaks is shown in Figure 24. Here, the concept of corner cut-out as shown in Figure 25 (non-peak plot) and in Figure 26 leads to a stress reduction of approx. 25%. Further information on the topic of long term performance of cold-bent insulating glass units can be found in [7], although no detailed information on stress limits is provided. Figure 26: FE analysis stress plot of primary seal (Van Mises stress) for load case 1, corner cut-out areas

Summary To achieve a ﬂush and capless outer glass appearance, many complex geometry cold-bent façade projects use structural silicone glazing systems to hold the glass panels in place. While this is architecturally a preferred and ideal solution, the façade engineering and structural designer is faced with the problem of long term tensile and shear forces on the structural silicone, caused by the glass intending to reverse the elastic glass cold-bending process and forming back to its initial ﬂat position. This effect is unique to cold-bent facades and different to hot bent glass facades, where the glass bending process causes a permanent (non-elastic) curvature of the glass. Besides the presentation of various graphs for the most common cold-bending geometries and a recommendation for workshop cold-bending and site re-bending to reduce structural silicone primary seal shear stresses, a new design concept for the structural silicone design of free-form cold-bent structural silicone glazed panels is presented in this paper. To push this new design concept to an agreed standard within cold-bent façade specialists and silicone suppliers, the author welcomes feedback and technical comments.

Acknowledgements The author kindly acknowledges Prof. Dr.-Ing. Eva Scheideler (University of Applied Sciences Ostwestfalen-Lippe, Germany) and her engineering ofﬁce for their support in carrying out the hyperelastic Neo-Hookean material model analysis with MSC Marc Mentat 12.

[1] Beer, B.: Structural Silicone Sealed Cold-Bent Glass – High-Rise Projects Experience Leading to a New Design Concept, Glass Performance Days, 2015

[5] Descamps, P., Kimberlain, J., Bautista, J., Vandereecken, P.: Structural Glazing: Design under high windload, IGS Magazine, Summer 2016 Issue

[2] Beer, B.: Complex Geometry Facades – Introducing a New Design Concept for Cold-Bent Glass, Glass Performance Days, 2013

[6] Vandereecken, P., PowerPoint “Positioning on FEA analysis”, Dow Corning, 2016

[3] Datsiou, K.C., Overend, M.: The mechanical response of cold bent monolithic glass plates during the bending process, Engineering Structures 117 (2016) 575-590, 2016

[7] Besserud, K.,Bergers, M., J. Black, A., Donald, L. D., Mazurek, A., Misson, D., Rubis, K.: Durability of Cold-Bent Insulating-Glass Units, Journal of ASTM International, Vol.9, No.3, 2012

[4] EOTA (2012); ETAG 002 - Guideline for European Technical Approval for Structural Sealant Glazing Kits (SSGK), Edition November 1999, 3rd amendment May 2012

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New Concept Of Horizontal Structural Elements In Glass: Self-Bearing / Shape Plate ENAR, Envolventes Arquitectónicas UPM Cerezo, Jesús M. Nuñez, Miguel A. Lauret, Benito Marco, José M. ENAR, Envolventes Arquitectónicas UPM Ariño Duglass KEYWORDS Structural glass • Pre-stressed glass • walkway glass • post-breakage glass beam

ABSTRACT A new design of structural glass application is presented, based on a horizontal self-bearing and pre-stressed glass solution. Our main objectives were to design, develop, manufacture and test a completely transparent slender walkway, having the particularity of being self-bearing. The starting point for the design has been the good behaviour of pre-stressed beams in terms of load capacity. Special care has been taken during the design state to fulfil five safety requirements: resistance, retention, redundancy, post-breakage resistance and standard regulations. For the design and verification of the model, analytic structural calculation as well as a finite element model have been carried out. The effect of different pre-stress loads and buckling behaviour of the element has been studied, obtaining the relationship between load capacity, deflections, maximum tensional stress in the glass and design parameters [1]. Finally, a full glass prototype has been manufactured and tested. During the loading stage, test deformation and the evolution of stress in glass has been monitored and meas-

Figure 1

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ured using a polariscope. The glass element has been led to breakage to validate the expected data of the design phase and obtain relevant information regarding the post-breakage behaviour. Load was increased up to 2.5 times design load to reach the breakage state and to hold 1.4 times the design load once reached the collapse state for 12 hours.

INTRODUCTION This research is the result of several years of study of glass beams, analyzing the problems with the brittle breakage and the safe post-breakage behaviors. The aim of this study is the design of a self-bearing prestressed glass element that achieves the features of maximum transparency and keeps a post-breakage capacity to be used in the ﬁeld of architecture. For this purpose, there will be inserted a pre-stressed reinforcement steel [2] and a ribbed section shape (that results from an optimized and evolved design). (See Figure 1)

DESIGN AND GEOMETRY The solid beam as concept is only used as a calculation model. Laminated beam will be used as many examples of skylight glass beams enhancing its transparency. Reviewing the state-of-the-art, we can say that the insertion of a pre-stressed reinforcement element will provide a safe breakage beam and a bigger load capacity [3] and against breakage. In the ﬁrst step of the evolved design, the beam will be compound of several laminated glass plies to keep them joined and to include a redundant or sacriﬁce leaf in case of breakage. The intermediate glass leaf is trimmed to place a steel rod. This rod will receive a strain of tensile from both ends that compresses the glass plies conferring bigger resistance (increasing the compressed areas and decreasing

Figure 2

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ENAR, Envolventes Arquitectónicas UPM

Figure 3

the tensile areas); otherwise, it increases the safety due to the reinforced steel rod that avoids glass fragments falling down. Because of the pre-stress applied, these fragments will be held together. The effect of pre-stressing in the laminated section provides lateral buckling; in order to avoid this effect a T shape will be obtained with a bespoke recess in the joint detail. This T shape will increase the inertia. The design will be optimized if the intermediate glass leaf is trimmed with a longitudinal curve shape to avoid the deﬂection due to the dead loads when the pre-stressing is applied. The linear gap conﬁnes the rod laterally. (See Figure 2) On the other hand, if the wings of the T become bigger to support a uniform distributed load, a problem could arise in the joint knot between the horizontal and vertical element obtaining an unstable element as well; to avoid this issue, the section of the T shape is doubled in TT shape solving the problem [4]. In this case, the moment diagram would work as a continuous beam over the ribs (and therefore in a very optimized way) getting a better stability as a prefabricated element easy to transport and install. Finally, the design could be improved by adding an antislip layer of thin glass with more impact resistance (3mm

Figure 4

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toughened plate). Also, it can be used as a sacriﬁce layer to be removed when scratched or broken. It would be better if all glass layers were low-iron glass. The self-bearing prefabricated element has a modular character to create slabs. There can be attached elements in 2 directions over a net of 6x6 m. The ribs are located in such a way that the distances between them are the same when more elements are joined. (See Figure 3) The isostatic glass slab weight is on the top of the pyramid in respect to the slenderness and lightness parameters regarding other slabs for the same loads. (See Figure 4) The general geometry is 6.00mX1.2m, length due to the common length of fabrication and width because of half width of a box of a truck. The height of the element does not have precedent in this kind of structural glass element, L/30, reducing the height and the effect of buckling [5]. Other researches use double height, around L/15. (See Figure 5)

HYPOTHESIS AND BASES OF CALCULATION We have adopted the bases of calculation for the glass plate for all the methods of calculation, so they will be performed for the scale 1:2 which will be the scale of the test sample: The dead load of the π glass plate at scale 1:2 is 1,10kN and the live load is 5kN/m2. The limit of the deﬂection will be L/500 since we need to ensure the feeling of stability. The admited calculation strain according to prEN 16612 will be 14.25 Mpa, according to the type of glass (annealed glass), the surface treatment (without treatment), the type of load (permanent), and the lasting of time (load with peaks as much as 11 hours continuosly).

Figure 5

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Figure 6

To justify the change of the scale in the 3 methods we have to hold the hypothesis that glass always breaks at the same strain in any scale and the deﬂections are proportional for the same loads. For simulating the uniform distributed load will be replaced by 2 supports located at L/4 from the ends to obtain a similar moment with a deﬂection that varies less than 10%.

CHECKING BY ANALYTIC CALCULATION For the analytic calculation, the element is simpliﬁed to half section “T” shaped with the same properties in terms of geometry, thickness and compression efforts on the ribs. The hypothesis in this case is that the glass board and ribs are working together monolithically as a single element.

Hypothesis Distance between supports Width of load Distributed load Linear load Point load Position of load (L/4) Pre-stress Vertical load

L= 3.00 m B= 0.60 m q= 5 kN/m2 q= 3 kN/m F = 4.5 kN a= 0.75 m N1= 7.5 kN; N2= 10 kN V1= 0.15kN; V2= 0.2kN

Geometry data

Figure 7

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Height of beam Width of beam Height of glass pane Width of glass pane Inertia Resistance module 1 Resistance module 2 Area Elasticity Modul

H1= 100 mm b1= 30 mm H2= 10 mm b2= 300 mm Ix= 706.25 cm4 W1= 91.13 cm3 W2= 217.3 cm3 A= 60 cm 2 E=73,000 Mpa

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Figure 8

For developing the analytic calculation, we start with a vertical load and a normal compression load on the ribs. This compression load is performed through a tensile rod with a curved shape, generating a vertical force against the vertical load. (See Figure 2) If the efforts of these actions are included in the strain graphics of the “T” shaped beam sections, we obtain the results shown below on the left where tensile strain decreases with pre-stressing to improve the glass behavior. (See Figure 6)

Glass: Extra clear is replaced by clear ﬂoat Glass board: laminated 10+10+10 is replaced by 10+5 allowing the curing of the UV adhesive through the 10mm monolithic glass. Ribs: Glass pane 19 is replaced by 10 because it is the more similar thickness and it allows the insertion of an 8mm rod. Layer/ Adhesive: SGP layer is replaced by PVB and UV adhesive.

CHECKING BY FEM SIMULATION For FEM simulation, there have been performed several hypothesis and premises to be close to the real test. The load is modeled on a surface of 2 cm in the whole width of the board and the total load is distributed on this surface. The supports are simulated on a lower line on the ribs to avoid distortions in the results; there will be single supports allowing the turns and limiting the 3 displacements in one of the ends and 2 displacements in the opposite one to allow the expansion and the action of the pre-stressing. For simulating the pre-stressing, load is located on the surface of the section of both ends. The strains will be monitored at the middle point of the upper surface of the board, in the lower area of the ribs, and the deﬂections related to different load steps for the 3 cases of comparison: Without compression, compression of 15kN and compression of 20 kN. The data for the design load is 9kN. (See Figure 7)

CHECKING BY TESTS First of all, we make several changes to adapt the glass plate to scale 1:2, based on the results of the state-of-art [6].

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Tensile rod: S275JR steel Ø16mm rod is changed by Ø8mm rod. The square shoes of support and pre-stressing keep proportional in thickness and geometry. Assembly π glass plate: The glass ribs will be located in the boxes of the glass board keeping a perpendicular manner and will be adhered with Panacol Vitricol UV. The lamp used is Panacol S 255 WT with the same brand of Vitralit. This UV adhesive reach stresses up to 23 MPa. After this, we have to pre-stress the Ø8mm tensile rods locating them into the gap created of 10mm and pre-stressing against the square shoes. In this case, the misaligned problems will be multiplied if the design of the ending elements are very complex. Pre-stressing of 7,5kN and 10kN are applied in each tensile rod that means 3/5 and 4/5 of its elastic limit. To perform the test, we have designed a self-bearing and a test bench. The measurement devices will be as follows: a load cell with digital screen, a comparator clock with articulated arm, a digital caliper, a polarimeter with speciﬁc software and a hydraulic jack as load applicator. (See Figure 8)

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Finally, the test process with the load phase in the elastic period was performed as follows: The π glass plate with dimensions 3.00m X 0.60m will support a uniform distributed load of 5 kN/ m² that means a single load of 9 kN split in two single loads at 1/4 and 3/4 from the ends with several steps of loads along 3 minutes by load step. After this, the load will be increased up to 9 kN x 1.5 =13.5 kN as safety test. There will be performed 3 load tests with 3 different conditions: pattern test without pre-stress, 15 kN prestress test (7.5kN each tensile rod) and 20 kN pre-stress

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test (10kN per tensile rod). In each of the 3 tests, several data will be monitored: the lower stress in the middle of the span in one of the ribs, the upper strains on the glass board and the deﬂection.

EXTRACTED RESULTS RESULTS OF TENSILE ON THE LOW POINT OF THE RIB The gap between the yellow graphic and the orange and red ones is due to the ﬁrst step of pre-stress. However, there is a short difference between two prestressed steps, that means it would have been suitable to apply increase the difference between pre-stress loads for improving the results. In the case of a non-pre-stressed beam, it has not been carried out a safety test because there was a big breakage risk overcoming the calculation resistance. (see Figure 9)

RESULTS OF TENSILE FROM THE UPPER POINT OVER THE GLASS BOARD Figure 9

There has been checked the stress on the laminated glass board according to the polarimeter: it is 7 MPa due to the pressure and temperature in the laminated process. The highest value of the compression stress is exactly from ribs without pre-stress because this is not balanced for any compression in the lower part and therefore it has highest values in tensile stress (below) and compression stress (upper). (See Figure 10)

RESULTS OF DEFLECTIONS

Figure 10

The deﬂection in the case of non-pre-stress is almost 50% in respect to the pre-stressed ones and there is a short difference between them. The constant created between the lines is almost parallel and is due to the contra deﬂection acquired in the process of pre-stress. (See Figure 11)

DIFFERENCES AMONG TEST RESULTS WITH DIFFERENT PRE-STRESS

Figure 11

Pre-stress improves mainly lower tensile stress and therefore also its resistance and breakage risk. The effect of pre-stressed causes a reduction of the upper stresses that means improving these stresses. Deflections are also improved giving stiffness and stability feeling. The big jump of improving in the lower stress and deformation are achieved in great amount with the first step of pre-stressing. The second step of pre-stressing confirms the trend but does not improves according to pre-stress increasing. (See Figure 12)

POST-BREAKAGE BEHAVIOUR (NON-ELASTIC PERIOD)

Figure 12

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This test of post breakage behavior is performed with a simulation of uniform distributed load (4 points) with a 20 kN of pre-stressing (10 kN per rib)

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There are different phases in the breakage and also there are 2 rules from the state-of-the-art that says than with the ﬁrst crack in the lower part in a test of 4 point is considered breakage; when the ﬁrst crack appears in the upper part of the board that is considered collapse. We are going to differentiate 3 phases: elastic period until breakage, and non-elastic period with breakage with loadbearing for some time and with collapse with loadbearing for some time.

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In the first step the deflections are proportional to the loads in the elastic period: The design load of 9 kN is reached with deflection of 3.3 mm The safety load (1.5 x 9 = 13.5kN) is reached with deflection of 5.2 mm The breakage is reached up to 22.5 kN (2.5 times design load) when the first crack appears in the lower part of the rib. (See Figure 13)

Figure 13

Figure 14

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BREAKAGE PHASE This crack in “V” shape is repeated until 3 times in an identic way in the same rib. This crack is characteristic extending in horizontal in the upper area because is the more compressive area. The crack does not reach the upper area and the reinforcement steel rods avoid the element from going down. Once the safety load is reached (22.5 kN) and cracks appear sequentially in the same way, so at the same time the element is going unloading until the stabilization at the load of 9kN (the design load by coincidence) with a deﬂection of 20mm (6 times bigger than without breakage) and keeping in this way for 6 hours when we decided to lead it

ENAR, Envolventes Arquitectónicas UPM

to the collapse. (See Figure 14)

COLLAPSE PHASE After post-breakage phase, the phase of collapse begins when the first crack appears on the upper surface of the board [7]; this is considered unsafety. That means although the sample was not collapsed keeping itself due to the adherence of glass panes and the rods of pre-stressed with all the layers broken, it is considered unsafety. In the test, the first crack on the horizontal surface appears at the load of 15 kN; in that moment, we stopped applying the load and decreased until 12.5 kN where it will be kept by itself with a deflection 65mm for 12 hours; in

Figure 15

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Celebrating 25 years of GPD in Finand

EXPERIMENTAL RANGE

Figure 16

The results have demonstrated safety against the breakage when is applied a pre-stressing decreasing the tensile at the lower area and getting smaller deflections. It is possible to increase the pre-stressing if we improve the quality or even if the section of the rod is increased. Since the breakage has reached 2.5 times the design load. With this result, we have achieved a safety collapse under our point of view. The box in the lower part of the board has controlled the lateral buckling of the ribs coming from due to compression effect and the deflection due to the loads. It is significant the importance of keeping the design load of 9,00 kN since the breakage for 6 hours and keeping for 12 hours the collapse phase with 1.4 times the design load. Finally, it has been shown a high level of breakage safety and we have achieved to take a little step forward against the brittleness of glass [9]. (See Figure 16).

that moment, we considered the end of the test. In this final figure, we can see how the test sample has finished the test after the loads supported and the lack of the visible collapse holding a load of 1.4 times the design load with an extension of deflection [8] of L/50 approximately. (See Figure 15)

REFERENCES:

CONCLUSIONS AND SUMMARY

3. BOS, F. P.; VEER; F.A.; HOBBELMAN, G.J. ; LOUTER P.C. (2008). Stainless steel reinforced and post-tensioned glass beams. Recuperado el 7 de Abril de 2008

GENERAL

1. AMADIO, C., & BEDON, C. (2010). Buckling of laminated glass elements in out-of-plane bending. Engineering Structures(32), 3780-3788. 2. CUPAC, J., MARTENS, K., NUSSBAUMER, A. ET AL. Glass Struct Eng (2017) 2: 3. doi:10.1007/s40940-017-0038-5

The prefabricated PI shaped glass plate has demonstrated its ability and safety post-breakage to become a reliable element for applying in the ﬁeld of architecture. The structural element achieved gets bigger transparency with less glass due to a slender section more optimized thanks to pre-stressing.

4. VEER, F. (2007). Walking on air, designing and engineering a glass bridge. Glass Performance Days (pp. 244-246). Tampere, Finlandia: GPD.

METHODOLOGICAL CONCLUSIONS

6. LOUTER, C. (2007). Experimental research on scale 1:4 models of an 18m reinforced glass beam, part i. Glass Performance Days 10th International Conference on Architectural and Automotive Glass. Tampere, 87-92.

The test at scale conﬁrms the analytic calculation results and the results coming from the FEM simulation within the elastic period and therefore the method is right. Test let to characterize the post-breakage behavior, impossible from the analytic study.

FROM MATERIALS The adhesive technology and its efﬁciency has been demonstrated without increasing unknowns even in the limit situation of breakage keeping the UV adhesive unalterable. Steel alternatives with more resistance will imply a more slender design.

5. LOUTER, C., BELIS, J., VEER, F., & LEBET, J. (2012). Structural response of SG_Laminated reinforced glass beams; experimental investigations on the effects of glass type. Engineering Structures (36), 292-301.

7. LOUTER, C. (2013). Reinforced and Post-tensioned Glass Beams. Tampere: GPD. 8. MARTENS,K; CASPEELE,R; BELIS, J (2015). Development of composite glass beams – A review. DOI: https:// doi.org/10.1016/j.engstruct.2015.07.006 9. MARTENS,K; CASPEELE,R; BELIS, J (2015). Development of Reinforced and Posttensioned Glass Beams: Review of Experimental Research. DOI: http://dx.doi. org/10.1061/(ASCE)ST.1943-541X.0001453

STRUCTURAL RANGE

ACKNOWLEDGEMENTS:

The pre-stressing designed improves the strains and the deﬂections of the glass plate and it is a way to optimize the sections achieving greatest slender. The weight per square meter is lighter for supporting the same load than the lightest steel or concrete slab.

The authors gratefully acknowledge the support provided by Ariño Duglass, Laguna Belvis and ENAR team.

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Structural Glass Sandwich Panels

Structural Glass Sandwich Panels Graham Dodd, Arup KEYWORDS: Glass, Honeycomb, Sandwich, Desiccant, Breather, Climatic

Abstract

Introduction

To provide stiffness, shading and privacy with abundant daylight and a feeling of openness for restaurant extensions and an entrance canopy to a London hotel, we used glass sandwich panels with aluminium honeycomb core. Similar construction had been used on smaller scale for interior decorative panels and for some interior ﬂoor panels but without engineering development. Exterior glass sandwich panels need durable strength and stiffness with continuing clarity, so we developed a detailed set of tests and acceptance criteria for all aspects of the appearance and performance of the panels with a specialist façade contractor. The panels were over twice the area of previous examples and too large for the established sandwich panel manufacturers so the contractor developed a new production method. When sealed sandwich panels are exposed to the weather, they experience changes of pressure in the entrained air, so need to be allowed to equalise. We proposed to ventilate the panels through canisters of silica gel desiccant to dry incoming air sufﬁciently to avoid condensation. The technique is commonly used to condition the expansion airspace above insulating oil in electrical transformers but was not known in the glazing industry. The technique has wide potential for façade applications.

Rogers Stirk Harbour + Partners designed extensions of the bar and restaurant and created a new entrance canopy composed of clear glass panels supported by carbon fibre beams for The Berkeley Hotel in London’s Knightsbridge. Project Partner, Amo Kalsi described the challenge to give guests the feeling of sitting in a bright, open space while being protected from the heat of the sun or the prying lens of the paparazzi. A reflective coating on the glass would prevent a view in during the day but would make the volumes look hard, heavy and monolithic from outside rather than light and transparent. At night, a reflective coating would not prevent a view in but would reduce the view out, making the spaces feel closed. Patterns of ceramic frit could blur the view in either direction but provide little shading and detract from the intended clarity and sparkle.

Fig 1 The Berkeley entrance

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Honeycomb panel applications Browsing our collection, comparing combinations of glass types and other materials, a number of shading and privacy devices, such as reflective louvers and plastic tube bundles, enclosed within double glazed units, seemed to offer some of what was required but none had the desired combination of clarity, privacy, sparkle and charm required. It was a combination that was as difficult to express as to achieve but when Amo referred to the marque “Bentley” it became clear that we needed a combination of technology and craft serving performance objectives, from which the aesthetic would emerge. We found a small sample of clear plastic sandwich panel with an aluminium honeycomb core and had seen honeycomb panels with glass skins used as interior dividers and glass floors, in projects like the Light House in North London by Gianni Botsford Architects. Playing with a variety of honeycomb sizes and seeing them sandwiched between glass, we noted the inevitable small variations in the geometry of the hexagonal cells that results from the process of stretching out the block from a stack of bonded foils. Far from being an undesirable ‘defect’ the variations lent interest and richness to the texture.

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Structural Glass Sandwich Panels

Performance Although the aluminium foil is only 50 to 70 microns thick, and therefore less than 0.8% of the cross sectional area, the thermal conductivity would be too high to form the insulating envelope of the building on its own. We did experiment with a Nomex paper honeycomb sample, which is a much better insulator, but the characteristic colour was not suitable in this case. Thermal insulation was provided by adding a conventional insulating cavity with laminated heat strengthened glass on the interior face of the structural honeycomb panels. The lower pane of the sandwich panel carried a durable solar reflective coating and the lower face of the insulating cavity had a low emissivity coating to minimise long-wave radiant heat gain from the honeycomb when exposed to direct sun, as well as to minimise heat loss. The effective shading coefficient or total solar heat gain was complex to estimate because of the geometry of the aluminium honeycomb and was simulated in a variety of ways to converge on an estimate. The properties are expected to be dependent on the angle of insolation but more research is required to characterise such composites fully. An advantage of using honeycomb bonded to the glass skins is that the resulting panel has much higher stiffness and strength than a simple laminated pane. This enabled the 4.5m high walls to be spanned vertically without mullions and the 1.9m wide roof panels to remain flat enough to allow a very shallow fall.

Development of the criteria Prior uses of glass honeycomb panels appeared all to be interior applications, where exposure to UV light and thermal changes were not so severe. In addition, the required sizes up to nearly 4.8m by 2.4m were too big for existing panel making facilities, so the appointed specialist contractor Bellapart elected to manufacture their own panels, which required selection of the clear adhesive and development of a production method for such large panels. The newly made panels would not have a track record of performance in service based on previous production, so it was essential to carry out a programme of testing to verify the properties and durability. We worked with specialist contractor Bellapart to identify the various potential failure modes to test for, ﬁnd or devise test procedures and agree acceptance criteria before testing commenced. [1] The testing programme included: • Yellowing under Xenon light 2000hr (EN-ISO 48922:2006); • Chemical compatibility with butyl and silicone sealants; • Fogging as a result of acrylate vapour condensation (by rapid cooling from 80oC to 12oC); • Interaction between desiccants and acrylate vapour; • Moisture ingress through perimeter seal and breather tubes;

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• Accelerated ageing in high moisture environment (EN1279-6:2003 Annex B) followed by tests of flatwise tensile (BS 5350-C6), compression and four-point flexural strength (EN 1288-3); • Cyclic temperature test to load the honeycomb with isochore pressure (based on EN1279-2); • Impact strength, soft body, EN12600; and • CWCT TN42 overhead glazing robustness. The adhesive finally selected from the four initial possibilities performed excellently, maintaining its clarity and mechanical properties. Bellapart developed a panel manufacturing cell complete with specially engineered mixing, de-airing and dispensing machinery to apply the adhesive to the glass panels and cure the assembly with UV light. The design was finalised in 2009 but construction was paused until 2015.

Climatic loads When sealed sandwich panels are exposed to the weather, they experience changes of pressure in the entrained air according to the ideal gas law pV = nRT The honeycomb core prevents the glass skins from deﬂecting, so in a sealed panel the full isochore pressure would be developed, which in this case would be up to 15kPa. [2] The average stress applied to the edges of the aluminium honeycomb appears to be relatively low isochore pressure/cross section of aluminium = stress on aluminium edge. 15000/0.008 = 1.9N/mm2 However, this would be additional to stresses arising from other structural loads, and would occur repeatedly over long periods. In fact, the production method does not make an adhesive bond simply to the edge of the honeycomb foil but forms a continuous ﬁllet joint between the glass and the walls of the honeycomb. In that joint, the stress is distributed to some extent but remains concentrated at the root junction where the aluminium foil meets the glass. To maximise the durability of the panels and avoid the risk of premature deterioration as a result of vapour seal failure, it was decided to equalise them to external pressure. Perforated honeycomb was used to allow equalisation, a common strategy in aerospace applications. [3]

Desiccant breather Allowing the units to equalise to atmospheric pressure introduced the challenge of keeping the cavity dry enough to avoid condensation during cold conditions. Although the perforations in the honeycomb would allow slow equalization of pressure between cells, the rate of

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Structural Glass Sandwich Panels

Potential applications

Fig 2 Perforated honeycomb bonded to glass

Honeycomb sandwich panels are very suitable for glass floors, owing to their high strength to weight ratio, providing post failure resistance is provided by tough laminated glass. The inherent obscuration provides modesty and reassurance while maintaining brightness. We applied a similar breather system to the spherically curved insulating glass units on the Las Vegas High Roller observation wheel in Nevada, USA because the glass could not be thermally tempered and the climatic loads would have been excessive for annealed glass. [5] Other reasons to equalise climatic load would be to avoid visual distortion arising from deflection of the glass, or excessive stress on edge seals. Various curtain wall systems, especially those with large cavities, are also being studied for application of the same technique. More research is needed to understand the details of moisture movement within façade systems, using desiccant breathers and designs will need to take note of diffusion and convection effects, including the lower density of moist air, in order to realise the full potential. The primary advantage is that because the desiccant can be replaced or regenerated remotely from the insulating glass, the life can be greatly extended. It may also be feasible to re-configure glazing design without the permanent bonding of panes, which would have advantages for upgrading in service and the re-use or recycling of materials at end of life.

Conclusions and Summary Fig 3 Desiccant breathers installed

diffusion between parts of the cavity would be slowed significantly, so a simple capillary breather tube was not considered to be a reliable solution because transient condensation could be trapped for long periods and biological growth might occur inside the unit. [4] Hydraulic systems, fuel systems, large gearboxes and oil-filled transformers all need to allow for flows of air to compensate volume changes and all need to avoid condensation from moist air drawn in, so a range of industrial desiccating breathers is available. These breather units contain silica gel granules, which are better than molecular sieves at releasing moisture into outgoing warm air, and inward and outward relief valves or an oil trap to keep the desiccant separated from external air until a small pressure difference exists to be relieved. Some systems even include moisture sensors, valves and a heater to re-generate the silica gel when it approaches saturation. In most cases, the low cost silica gel is replaced periodically. The air inside the system does not achieve the very low dew-point typical of a new hermetically sealed insulating glass unit but in most cases will be low enough to prevent transient condensation when the glass gets cold.

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Structural glass sandwich panels with honeycomb core have been shown to be durable and to have unique architectural qualities including light transmission, shading, privacy and high stiffness to weight ratio. To maximise the durability of honeycomb panels, the desiccant breather technique was applied, which has applications where climatic loads need to be equalised or where it is advantageous not to bond panes permanently together.

References [1] Teixidor, C. The Berkeley glass pavilion – Design and construction. GPD 2009, Tampere. [2] Feldmeier, F.: Belastung des tragenden Randverbundes von Isolierglas bei Structural Glazing durch klimatische Einﬂüsse. Fraunhofer IRB Verlag, Stuttgart (1999) [3] Rinker, M.: Analysis of an Aircraft Honeycomb Sandwich Panel with Circular Face Sheet/Core Disbond Subjected to Ground-Air Pressurization NASA, Hampton, 2013 [4] Rose, A. Pressure-equalised insulating glass units – a feasibility study, IFT Rosenheim, 2015 [5] Smith, A. Atmospheric Loads and the Design of Curved Insulating Glass Units, GPD 2001, Tampere.

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Smart glazing in intelligent buildings

Smart glazing in intelligent buildings: what can we simulate? Fabio Favoinoa, Luigi Giovanninic, Roel Loonend a Eckersley O’Callaghan Ltd, 236 Gray’s Inn Road, WC1X 8HB London, UK b Glass and Facade research group, University of Cambridge, Trumpington Street, CB2 1PZ Cambridge, UK c Department of Energetics, Politecnico di Torino, Corso Duca degli Abbruzzi 24, 10141 Torino, Italy d Building Physics and Services, TU Eindhoven, Postbus 513 5600 MB, Eindhoven, the Netherlands KEYWORDS building performance simulation, smart glazing, adaptive facades The integration of smart glazing and adaptive façade in buildings can lead to large performance improvements and added functionality compared to conventional static building envelope systems. This is achieved not only by embedding automatic/ controllable (smart/active) switchable materials into the building envelope, but also including intelligence into the way the whole building is designed and operated. Desk studies and Building Performance Simulation can be used to support the design process of these technologies and of the building integrating them, as well as to support product development aimed at building integration of novel switchable glazing technologies. Although BPS tools traditionally lag behind the development of novel technologies and

Introduction The potential of smart (switchable or adaptive) glazing technologies to improve building performance is due to their ability to modulate their thermo-optical properties in response to external stimuli, enabling the modulation of the amount of solar radiation entering the indoor environment in response to transient boundary conditions (external, such as climate, or internal, such as occupants’ requirements). The main purposes two adopt a switchable glazing are to improve: a) indoor environmental conditions in terms of visual (e.g. daylight utilization, glare discomfort, view to outside) and thermal (e.g. overheating in summer) comfort aspects, as well as privacy;

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adaptive building envelope systems, therefore it is not always possible or easy to evaluate in an accurate and comprehensive way the performance of building integrated switchable glazing technologies, and in general adaptive facades. In this paper we outline the main requirements for BPS of smart glazing. These include user interface requirements, models availability, integration of physical domains, integration and customisation of control strategies. We analyse possible BPS tools that could be used and their main advantages and drawbacks, and describe the latest advances for more integrated simulation methodologies and tools, included an ad-hoc developed simulation tools which aims at overcoming the main limitation of traditional BPS tools.

b) building energy use and carbon emissions (by reducing heating, cooling and lighting energy use at the same time, by controlling these switchable glazing in an intelligent way). Different materials and systems are used as functional layers to modulate thermo-optical properties in switchable glazing, including, chromogenic materials (e.g. thinﬁlm metal compounds), liquid crystals and suspended particles. The main differences between various types of switchable windows can be summarized with the following features: a) Control mechanism: referring to the terminology in (Loonen, 2013)), extrinsic control refers to the use of an

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Smart glazing in intelligent buildings

external signal (i.e. electrochromic and liquid crystal devices, LCD), while intrinsic control refers to the essential feature of the material to vary its thermo-optical properties in an autonomous way in response to changing boundary conditions, e.g. as a function of temperature (i.e. thermochromic, thermotropic) or incident light (i.e. photoelectrochromic, photovoltachromic) etc.. b) Wavelength range: switchable windows can modulate thermo-optical properties in the whole solar spectrum, or only in the visible part, non-visible part or independently in both parts of the solar spectrum (De Forest et al. 2017). c) Optical properties: solar radiation can either be reﬂected to outside or absorbed by the smart glazing. Moreover, depending on the variation of the refractive index of the materials embedded in the functional layer, a switchable glazing could have a diffusive behavior when activated (as thermotropic and LC devices), contributing to reduce glare risk from direct solar radiation and to distribute light more uniformly in the indoor space, instead of maintaining the specular state. Smart glazing compete with dynamic solar shading technologies on different aspects, from improved building performance, to building and component integration issues, control strategies, maintenance strategies, initial and operating costs etc.. Both smart glazing and dynamic

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solar shading technologies present different advantages and disadvantages, which may be generally valid or project specific. This comparison is not in the scope of this paper, although most of the considerations presented in this work regarding the evaluation of their performance can be applied to both. Different types of switchable windows are commercially available on the market (Fig. 1 and 2). Baetens et al. (2010), Jelle et al. (2012) and Favoino et al. (2015) provide extensive overviews of the state-of-the-art in this field. Input data for switchable windows is available at glazing manufacturers such as View Inc, SAGE (electrochromics), Raven Windows (thermotropics), Merck (liquid crystals), and via the International Glazing Database (IGDB) that is linked to the LBNL Window software. In figure 1 the performance of established (continuous lines) and innovative (dashed lines) smart glazing technologies is compared to conventional static glazing (data points) in terms of thermo-optical properties (g-value on the x-axis and visible transmission on the y-axis), the main difference and advantage is that smart glazing (continuous and dashed lines) are able to modulate their properties between different states compared to conventional glazing, represented only by one set of properties (data point). Besides the capability of the switchable glazing to actively manage the solar radiation entering the built

Figure 1. Comparison of switchable glazing integral solar properties compared with conventional double glazing units (grey data points) (Favoino 2015).

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Smart glazing in intelligent buildings

performance aspects of a building. The interactions between these physical domains need to be taken into account in an appropriate way, depending on the purpose of the evaluation (i.e. the building performance indicators under evaluation) and on the control mechanisms of the switchable glazing. Whenever a thermal/ energy performance indicator need to be evaluated (i.e. building loads, building energy use, temperatures, thermal comfort etc…) together with a visual comfort indicator (i.e. glare index, light levels etc.) and/or the adaptation of the façade is triggered by a result in another physical domain, Figure 2. View of different smart glazing technologies: A) thermo-tropic, B) electro-chromic, C) Fluidglass, d) Photo-Volta-Chromic, e) Tunable Visible-Infrared Reflector. virtual physical models representing only one physical domains (i.e. only thermal or visual) or two independent environment, it is the way it is controlled that finally physical domains (i.e. one thermal and one visual model determine which performance objective is improved and independent from each other) cannot provide reliable to which extent, as an adaptive behaviour itself does not results (Favoino et al. 2017) (cf. Section 4). automatically guarantee effective operations (Wickmans et al. 2005). In this context, Building Performance b) User interface definition of switchable glazing: Two Simulation (BPS) a quantitative and true comparison types of modelling approaches can be distinguished: (i) between different materials (either adaptive or static), application-oriented and (ii) general-purpose approach. products and controls, by means of overall building Application-oriented (AO) indicates that the user can performance metrics, i.e. total primary energy, comfort/ select a specific material / glazing model between the discomfort indexes, overall indoor environmental quality one already available in the BPS tool. Therefore the and whole life value indicators etc.. However, simulation switching mechanisms and how it is triggered are already of smart glazing can be significantly more complex than embedded in the specific model, and users can activate it performance prediction of conventional static facades, easily by means of the graphical user interface, but they as existing simulation tools were not originally developed are limited to the pre-sets available. The general-purpose for this purpose. (GP) features, on the other hand, are not restricted to The present paper aims at guiding professionals and a specific technology, but offer the user flexibility to researchers in understanding the issues related to BPS of define the way thermo-physical properties varies within smart glazing, and selecting the best suited models, tools the switchable glazing and/or their control mechanisms and simulation strategies to suit their purposes. (either passive or active).

2. Building Performance Simulation requirements for smart glazing Most BPS tools stem from a time when variation of thermo-optical properties of building components and their control was not a primary consideration (Oh and Haberl 2015), restricting the options for modelling switchable glazing and adaptive facades. The requirements and limitations of BPS tools to evaluate the performance of buildings integrating switchable glazing can be grouped into the following areas (Loonen et al. 2016): a) Multi-domain integration of performance evaluation Switchable glazings inﬂuence both visual and thermal

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c) Solution routines for transient heat conduction through building elements: it is important that the switching of window properties happens during simulation run-time, because the changing amount of solar radiation that enters the zones leads to a different transient thermal response of the space. Although the methods to solve heat transfer phenomena differential equations in BPS tools can only work with time-invariant thermophysical properties (i.e. density, speciﬁc heat capacity, thermal conductivity), the models for calculating energy gains/losses through transparent portions of the building envelope, on the other hand, do not normally include

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Smart glazing in intelligent buildings

thermal storage effects (Freire et al. 2011). For this reason it is easier to take dynamically changing window properties into account. d) Control strategies: for AO options, the user can only select between the control strategies pre-coded in the BPS tools (hard-coded control), whether these are intrinsic (depending on a state of the material, i.e. glazing temperature) or extrinsic switchable glazing (depending on an external stimulus, i.e. room air temperature). Time-scheduled control is generally available, but the user can only pre-define control actions as a function of time. Some BPS tools presents script-based control capabilities, allowing the user to code the preferred control strategy in the simulation tool, replicating and extending the hard-coded pre-set options to suit the specific control requirements of the switchable glazing. Hard-coded presets or script-based controls are extremely suitable for evaluating the performance of rule based controlled switchable glazing, this is by far the most adopted control option in the market (Oldewurtel et al. 2012), and many studies adopts this to test the performance of switchable glazing technologies (Jonsson and Ross, 2010; Fernandes and al. 2013). More advanced control strategies for switchable glazing, such as advanced rule based or Model Predictive Control strategies, can only be evaluated by adopting script based control in combination with more advanced simulation strategies (Favoino et al. 2016, De Forest et al. 2017, cf. Section 4). e) Occupant interaction: scarce information and modelling capabilities is available to model the way individual occupants may want to control a specific switchable glazing technology. This capability requires behavioural models that describe the interaction of building occupants with adaptive building envelope systems. Until now, such occupant interactions can only be implemented via scriptbased control approaches (Yan et al. 2015, Gunay et al. 2015). Based on these requirements building designers and researchers need to assess the most appropriate tool and methodology to simulate switchable glazing to suit their purpose. In Figure 3 a flow chart diagram is used to guide this evaluation, to understand whether the switchable glazing under investigation can or cannot be simulated with current BPS tools, and which modelling approach should be used.

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3. Implementation of smart glazing models and controls into BPS tools As a result of their presence in the market, options for AO modelling of switchable glazing technologies are embedded in many of the widely-used simulation tools (EnergyPlus, ESPr, IDA ICA, IES VE and TRNSYS). Such implementations offer the possibility to control the properties of the building model’s fenestration systems during simulation run-time. 3.1. Application oriented modelling capabilities Most of extrinsically controlled switchable glazing, such as electrochromic, SPD and liquid crystal devices could be modelled in BPS tools with the AO approach, by deﬁning different glazing states (each one with speciﬁc thermo-optical properties) and linking these with a pre-set hard coded control. The differences between the various implementations are the number of possible window states (e.g. on/off versus gradual transitions) and the simulation state variables that can be used for the control of adaptation (e.g. room temperature, ambient temperature and incident radiation). Intrinsically controlled switchable glazing, such as thermotropic/chromic windows, are slightly more complicated to simulate than other switchable window types because of: a) intrinsic control: adaptation of the fenestration properties is directly triggered by window material temperature instead of a control signal that is based on more general simulation variables; b) hysteretic behavior: most thermochromic / thermotropic functional layers presents a different variation of thermal properties according to material temperature

Figure 3. Proposed workﬂow to select BPS tools according to simulation requirements and characteristics of switchable glazing technology.

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Smart glazing in intelligent buildings

Figure 4. Implementation of Application Oriented modelling and control capabilities in existing BPS tools.

when undergoing heating or cooling (Warwick et al, 2013). This hysteresis can have a significant impact on the heating and cooling energy use of buildings (Warwick and Binions, 2014), although until no study exists on the influence of this behavior also on thermal and visual comfort. A provision for thermochromic window simulation is implemented in EnergyPlus since v3.1 and ESP-r. The input of these models consists of sets of glazing thermo-optical properties at various temperatures. During the simulation, the thermochromic layer temperature of the previous time step is automatically fed into a window control algorithm, which then selects the window properties that best match with the given temperature. In IDA ICE and Trnsys, it is also possible to model thermotropic/chromic windows, but a significantly higher level of work and expertise is required from the user side because a script for the control strategy needs to be manually developed by the simulation user. The hysteretic behavior of switchable window cannot be modelled in any BPS tools (Saeli et al., 2010), although some researchers developed a simplified approach to evaluate its effect (Warwick et al, 2013) by a two-step simulation process, aimed at developing a correlation between thermochromic window states (optical properties) and climate boundary conditions (i.e. solar irradiance on the glazing). Figure 4 shows how 5 of the most adopted BPS tools implement AO modelling capabilities and control modelling capabilities. These tools (EnergyPlus, ESPr, IDA ICE,

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IES VE and TRNSYS) are selected as they present i) the largest user community among designer and researchers, ii) extensive building envelope modelling capabilities and iii) they are widely validated. On the right of Figure 4 different switchable glazing technologies are represented and connected with the BPS tool which presents any AO modelling capabilities regarding that specific technology. While on the left hand side of Figure 4, the control options available in each simulation tool are outlined. Not all hard coded control options are available for all switchable glazing technologies, especially for intrinsic technologies (i.e. thermochromic glazing). This graphical representation will be hosted in a web based tool, allowing the user to define the switchable glazing technology and its control strategies and to identify to most suited simulation tool to fit his/her purpose, and vice-versa to select his/her preferred simulation tool and understand its modelling capabilities. 3.2. General purpose modelling capabilities In order to overcome the limitations set by AO modelling approaches, researchers and designers oriented towards the tools allowing more GP modelling approaches. EnergyPlus, ESPr and TRNSYS allow the user to adopt the general oriented approach to simulate a smart glazing: a) ESP-r: this is a simulation tool with an open-source environment aimed at the research community. Since its first version, various groups have contributed general-purpose functionalities for modeling adaptive facade technologies. The (i) transparent multi-layer

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Smart glazing in intelligent buildings

Celebrating 25 years of GPD in Finand

Fig 5. Modelling and simulation logic of the EMS-EnergyPlus “Surface construction state” actuator, TRNSYS Type 56 “WindowID” Actuator, EPSr “transparent multi-construction control”.

construction control and (ii) special materials (Evans and Kelly 1996), allow a general purpose modelling of switchable glazing; b) TRNSYS: the multi-zone building model (TYPE 56) is one out of a large number of possible system components. The variable window id option and a controllable bi-directional scattering distribution function (BSDF) (Hiller and Schöttl 2014) are directly implemented in TYPE 56. All other adaptive features in TRNSYS can be activated by manipulating (i.e. switching on/off or modulating) the connections to and from the TYPE 56 building model, via equations using either the graphical Simulation Studio or by editing text ﬁles; c) EnergyPlus: of all software tools analysed, EnergyPlus has had the largest growth in adaptive facade modelling capabilities since it was developed. Most notably, these developments have been driven by the introduction of the EnergyPlus Runtime Language (Ellis, Torcellini, and Crawley 2007), aiming at replicating a real building Energy Management System (EMS). The system is based on the same elements of a real EMS – that is, sensors, control logics and algorithm, and actuators. In the latest release of the EMS system (US DOE, 2015) new actuators were introduced in order to control thermo-optical properties of the building envelope in a more ﬂexible way. A control algorithm can be designed in the EMS, adopting the ERL programming language, in order to control any actuator, based on data from the sensors. Any output from EnergyPlus can be adopted as a sensor, together with outputs from any other independent virtual model, allowing

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the integration of results from other BPS tools (i.e. Radiance for daylight results). In ESP-r only two states of the glazing could be modelled, while in ESP-r and TRNSYS only few simulation outputs could be used as a sensor for the control. EnergyPlus appears to be the most comprehensive and flexible tool to evaluate the performance of switchable glazing when building integrated. In fact within its EMS, the “Surface Construction State” actuator can be used to simulate variable thermo-optical properties, and therefore an adaptive glazing (Actuated Component Control Type: Construction State; Actuated Component Type: Surface). This specific actuator allows to interchange during simulation runtime different constructions, characterised by different material properties, for the same building surface, according to a user specified control strategy. This GP modelling approach could be used to simulate the behaviour of switchable glazing, whereas different transparent constructions can be defined for each state the switchable glazing can assume during building operations, and an algorithm can be designed to control it according to the mechanisms triggering adaptation (i.e. phase/temperature change, electric signal, electron migration due to solar radiation etc.). By designing the control algorithm, the user could define either a novel intrinsically controlled smart glazing (controlled based on material states or climatic boundary conditions), or set-up a novel control for extrinsically controlled switchable glazing which is not included in BPS hard-coded presets. In fact, in order to simulate other passive or active switchable glazing technologies, the control can be based

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on the signal from sensors such as: temperature of the construction element (thermo-chromic/tropic glazing); amount of solar radiation on the external side of the glazing (photo-chromic glazing); heating or cooling demand, amount of daylight in the indoor environment (for electrochromics and liquid crystals, or shading devices), etc.. The logic of the “Construction State Actuator” of the EMS is schematized in Fig. 5, this is similar to the TRNSYS “WindowID” and ESPr “transparent multi-construction control” actuators. This logic is divided in four sequential steps defining: i) the actuators, in this case different glazings each one with the properties of one alternative state of the switchable glazing; ii) the sensors, identifying the boundary conditions whom the control of the switchable glazing will be controlled on; iii) the control algorithm, how the variation of the boundary conditions ultimately influence the variation of the switchable glazing states; iv) the actions, identifying which of the glazing state, which building services state (i.e. air flow or dimmable artificial lighting power) and which building occupant state (i.e. thermal comfort or visual comfort indicator) can be associated with each sets of boundary conditions.

4. Limitations of current BPS tools and future outlook Although switchable windows are one of the most mature adaptive façade technologies, when it comes to integration in building performance simulation tools, there are still some issues that require further research. Based on the presented review, the following points requires particular focus:

Smart glazing in intelligent buildings

a) few documentation is available on the validation of AO and GP modelling approaches for switchable glazing; b) many switchable window coatings have special angular-dependent optical properties that are different from regular specular glazing systems. It is not always straightforward to introduce such effects in building performance simulation tools; c) some switchable window technologies, especially electrochromic materials have a delay of 10 to 20 minutes between actuation and actual coloration of the window. This effect may have significant impact on window performance, particularly for visual comfort and glare; it is nevertheless not possible to take this effect into account in most simulation tools; d) it is currently not always possible to model the effects of windows that can independently control switching in various parts of the solar spectrum; e) some switchable window technologies, especially thermochromic / thermotropic materials have an hysteretic dependence of optical properties on temperature. This effect have significant impact on the window energy performance, and may have significant impact on thermal and visual comfort; although it is not possible to take this effect into account in any simulation tool; f) it is not always straightforward and sometimes not possible to perfectly integrate the control of switchable glazing with the control of HVAC and artificial lighting systems; g) the number of possible control strategies available for extrinsically controlled switchable window is very limited;

Figure 6. Architecture of advanced simulation strategies for switchable glazing.

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Smart glazing in intelligent buildings

h) the implementation of novel smart glazing technologies and innovative controls by means of GP approaches require an extensive user expertise, due the lack of appropriate user interfaces allowing more efficient integration with the design process; i) it is not possible to correctly evaluate the interaction between thermal and visual effect of controlling a switchable window within a single BPS tool, especially for technologies not implement in AO models or controls which are not hard-coded in the simulation tool already. In order to overcome most of these limitations, researchers have been adopting workarounds and simplified simulation strategies or more advanced simulation strategies. 4.1. Simplified simulation strategies The building integrating the switchable glazing can be represented by a series of independent building models, each one representing the building with the switchable glazing in a different glazing state (i.e. with different glazing thermo-optical properties). The results of the independent building models can then be combined at a post-processing stage in an attempt to capture the performance of a building integrating a dynamic component (i.e. switchable glazing for which a model is not available yet), and/or to mimic more advanced building operations (Kasinalis et al. 2014; DeForest et al. 2013). This discrete approach works well for facade systems with long adaptation cycles (e.g. seasonal), but it cannot accurately model short-term adaptive building envelope dynamics, as it fails to account for the effect of delayed thermal response arising from the capacitance of building components (i.e. slabs, walls and internal partitions). These inaccuracies may eventually compromise decisionmaking based on simulation outcomes, but little information about this issue is reported in literature. 4.2. Advanced simulation strategies Whenever more than one physical domain need to be simulated at the same time (i.e. thermal and visual performance of a switchable glazing) the main approach is to integrate in a coordinated simulation strategy different BPS tools, enabling either the exchange of information between different models, or co-simulating the different models involved. Co-simulation, in particular, is a simulation strategy in which two or more simulators solve systems of coupled equations, by exchanging data during simulation run-time (Trcka et al. 2009). This strategy could become particularly important for performance prediction of switchable glazing, as it enables to (i) integrate the simulations over different interrelated physical domains (i.e. thermal and visual), (ii) evaluate emerging technologies for which models may not be directly available in the specific BPS tool used, and (iii) assess the potential of advanced control strategies of switchable glazing. In order to use these more advanced simula-

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Celebrating 25 years of GPD in Finand

tion strategies the exchange of information need to be enabled by GP modelling approaches or by middle-ware software, while for co-simulation the use of a middle-ware software is essential (such as MATLAB or BCVTB, Wetter 2011). Optimisation middle-ware could be added to the simulation strategy to optimise the switchable glazing control strategy, as shown by Favoino et al. (2016). Figure 6 shows the usual architecture of advanced simulation strategies, involving i) a coordination layer (or software) for model communication or co-simulation; ii) an optional optimisation layer (software) to eventually optimise the control of the switchable glazing; iii) the evaluation layer constituted by the different building virtual models. The main limitation of advanced strategies is the additional work required to the modeller, to create the virtual building models in different physical domains and coordinate or exchange of information between these models by programming and scripting. 4.3. Current research activity and future work Within the COST Action TU1403 – Adaptive Facade Network, which EOC is actively contributing to, the authors are developing an advanced simulation strategy and a graphical user interface to overcome most of the limitation of current BPS tools, based on a deep understanding and evaluation of the complexity of the requirements and capabilities of the simulation tools reviewed in this paper. This novel simulation tool aims at evaluating the building performance of switchable glazing (and adaptive facades in general) when integrated with buildings and their occupants in a more accurate and comprehensive way. It integrates EnergyPlus (thermal, airflow and HVAC simulation) with Radiance (daylight simulation) in a parametric environment (Grasshopper and Rhino), in order to be able to interface with 3D models and with the design process in a more efficient way. Figure 7 shows the Grasshopper interface of the simulation tool and some example results. The advanced simulation strategy adopted by this tool, was extensively validated and demonstrated in numerous publications, regarding: i) the definition of an ideal switchable glazing able to minimise building energy use (Favoino et al. 2015); ii) the assessment of innovative control for a novel photovoltachromic switchable glazing (Favoino et al. 2016); iii) the design and control optimisation of novel adaptive insulation technologies (Favoino et al. 2017). The next steps of the research, by means of the developed simulation strategy and interface, are to: a) evaluate the effect of the hysteresis of thermochromic glazing on energy and visual comfort related aspects; b) evaluate the performance of novel switchable glazing (and innovative controls) on large scale projects; c) develop further the parametric graphic user interface to support general purpose modelling approaches and to provide a more efficient and user friendly way define advanced control via script based approaches.

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5. Conclusions The presents paper provides an overview of the requirements and capabilities of Building Performance Simulation tools to evaluate the performance of building integrating switchable glazing. The modelling approaches capabilities of different Building Performance Simulation tools are analysed and compared with the requirements set from a technological point of view. Currently these tools offer an application-oriented approach, which restricts the modelling capabilities to the switchable glazing models and controls pre-coded in the specific simulation tool. Although some of therm have started to present a more flexible modelling approach, named by the authors “general purpose”, allowing flexibility

Smart glazing in intelligent buildings

to model switchable glazing and controls which are not ready available in the BPS tools interface. Nevertheless different issues need to be addressed in order to provide a comprehensive method and tool to evaluate building integrated switchable glazing, mainly regarding physical domain integrations, advanced control simulations and accuracy of speciﬁc switchable glazing models. These different issues are discussed and an ad-hoc developed simulation strategy and tool is presented, with the aim to address most of the limitations of current BPS tools, while supporting in a more efﬁcient way the design process of building integrating switchable glazing and the product development of novel switchable glazing technologies.

Figure 7. Top: Grasshopper Interface of the novel simulation tool for adaptive facade; Center: Goal based yearly results; Bottom: Resulting control of three state switchable glazing to meet performance goals.

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Shaping ultra-thin glass

Acknowledgement The authors would like to acknowledge the COST Action TU1403 – “Adaptive Facades Network” for providing excellent research networking opportunity.

References Baetens R., Jelle B.P., Gustavsen A., (2010). Properties, requirements and possibilities of smart windows for dynamic daylight and solar energy control in buildings: A state-of-the-art review, Sol. Energy Mater. Sol. Cells. 94, 87–105 DeForest, N, A Shehabi, G Garcia, J Greenblatt, E Masanet, E.S. Lee, S. Selkowitz, and D.J. Milliron. (2013). “Regional Performance Targets for Transparent near-Infrared Switching Electrochromic Window Glazings.” Building and Environment 61 (March). Elsevier Ltd: 160–68.

Celebrating 25 years of GPD in Finand

Jelle B.P., Hynd A., Gustavsen A., Arasteh D., Goudey H., Hart R., (2012). Fenestration of today and tomorrow: A state-of-the-art review and future research opportunities, Sol. Energy Mater. Sol. Cells. 96, 1–28. Jonsson A., Roos A. (2010). Evaluation of control strategies for different smart window combinations using computer simulations, Solar Energy 84:1, 1-9, ISSN 0038-092X, http:// dx.doi.org/10.1016/j.solener.2009.10.021 Kasinalis C., Loonen R.C.G.M., Cóstola D., Hensen J.L.M., (2014). Framework for assessing the performance potential of seasonally adaptable facades using multi-objective optimization, Energy Build. 79, 106–113. Loonen, R.C.G.M., TrÐka, M., Cóstola, D., Hensen, J.L.M., (2013). Climate adaptive building shells: State-of-the-art and future challenges, Renewable and Sustainable Energy Reviews 25: 483493, ISSN 1364-0321

DeForest N., Shehabi A., Selkowitz S., Milliron D.J., A comparative energy analysis of three electrochromic glazing technologies in commercial and residential buildings, Applied Energy, Volume 192, 15 April 2017, Pages 95-109, ISSN 0306-2619, https://doi. org/10.1016/j.apenergy.2017.02.007.

Loonen, R.C.G.M., Favoino, F., Hensen, J.L.M. & Overend M, (2016). Review of current status, requirements and opportunities for building performance simulation of adaptive facades, Journal of Building Performance Simulation, DOI: 10.1080/19401493.2016.1152303

Ellis, P. G., Torcellini, P.A. and D. B. Crawley (2007). “Simulation of Energy Management Systems in EnergyPlus.” In Proceedings of Building Simulation 2007, 1346–53.

Oldewurtel F., Parisio A., Jones C.N., Gyalistras D., Gwerder M., Stauch V., Lehmann B., Morari M., (2012). Use of model predictive control and weather forecasts for energy efﬁcient building climate control, Energy and Buildings, 45, 15-27, ISSN 0378-7788, http://dx.doi.org/10.1016/j.enbuild.2011.09.022

Evans, M., and N. J. Kelly (1996). Modelling Active Building Elements with Special Materials. ESRU Occasional Paper, University of Strathclyde, Glasgow Favoino F., Overend M., Jin Q., (2015). The optimal thermo-optical properties and energy saving potential of adaptive glazing technologies, Appl. Energy 156, 1-15. Favoino F, Fiorito F, Cannavale A, Ranzi G, & Overend M., (2016). Optimal control and performance of photovoltachromic switchable glazing for building integration in temperate climates, Applied Energy, Volume 178, 15 September 2016, Pages 943-961, ISSN 0306-2619, http://dx.doi.org/10.1016/j.apenergy.2016.06.107. Favoino F., (2017). Building Performance Simulation of adaptive facades, PhD thesis, University of Cambridge, UK. Favoino F., Jin Q., Overend M. (2017), Design and control optimisation of adaptive insulation systems for ofﬁce buildings. Part 1: Adaptive technologies and simulation framework, Energy, Volume 127, 15 May 2017, Pages 301-309, ISSN 0360-5442

Oh, Sukjoon, and Jeff S. Haberl (2015). “Origins of Analysis Methods Used to Design High-Performance Commercial Buildings: Whole-Building Energy Simulation.” Science and Technology for the Built Environment 4731 (October): 1–20. doi:10 .1080/23744731.2015.1063958. Saeli, M., Piccirillo, C., Parkin, I.P., Binions, R., Ridley, I. (2010). Energy modelling studies of thermochromic glazing, Energy Build. 42, 1666–1673 Trcka, M., J.L.M. Hensen, and M. Wetter (2009). “Co-Simulation of Innovative Integrated HVAC Systems in Buildings.” Journal of Building Performance Simulation 2 (3): 209–30. doi:10.1080/19401490903051959. U.S. DOE (2015). “Application Guide for EMS Energy Management System - User Guide.” http://nrel.github.io/EnergyPlus/EMS_ Application_Guide/EMS_Application_Guide/.

Fernandes L.L., Lee E.S., Ward G., (2013). Lighting energy savings potential of split-pane electrochromic windows controlled for daylighting with visual comfort, Energy and Buildings 61, 8-20, ISSN 0378-7788, http://dx.doi.org/10.1016/j.enbuild.2012.10.057.

Warwick, M. , Ridley, I. and Binions, R., (2013). The Effect of Transition Hysteresis Width in Thermochromic Glazing Systems. Open Journal of Energy Efﬁciency, 2, 75-88. doi: 10.4236/ojee.2013.22011.

Freire, R. Z., Mazuroski, W., Abadie, M.O., and N. Mendes (2011). “Capacitive Effect on the Heat Transfer through Building Glazing Systems.” Applied Energy 88 (12): 4310–19. doi:10.1016/j. apenergy.2011.04.006.

Warwick, M.E.A., Binions, R., (2014). Advances in thermochromic vanadium dioxide ﬁlms, Journal of Material Chemistry A 2, 3275–3292

Gunay, H. B., O’Brien, W., & Beausoleil-Morrison, I. (2015). Implementation and comparison of existing occupant behaviour models in EnergyPlus. Journal of Building Performance Simulation, 1-46. Hiller, M., and P. Schöttl (2014). “Modellierung Komplexer Verglasungssysteme in Trnsys.” In Proceedings of BauSIM2014, the Fifth German-Austrian IBPSA Conference, 387–94 Hong, T., D’Oca, S., Turner, W.J.N., and S. C. Taylor-Lange (2015). “An Ontology to Represent Energy-Related Occupant Behavior in Buildings. Part I: Introduction to the DNAs Framework.” Building and Environment 92: 764–77. doi:10.1016/j.buildenv.2015.02.019.

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Wetter, M. (2011). “Co-Simulation of Building Energy and Control Systems with the Building Controls Virtual Test Bed.” Journal of Building Performance Simulation 4 (3): 185–203. doi:10.1080/194 01493.2010.518631 Wickmans, A., Aschehoug, O., Hestnes, A. G., (2005). The intelligent Building Envelope – Concept and Qualiﬁcations, Glass in Buildings Conference Proceedings, Bath, UK. Yan, D., O’Brien, W., Hong, T., Feng, X., Gunay, H. B., Tahmasebi, F., & Mahdavi, A. (2015). Occupant behavior modeling for building performance simulation: current state and future challenges. Energy and Buildings, 107, 264-278

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Kuraray Europe Gmbh

Exciting architectural case studies from all around the world

Sandro Casaccio, Kuraray Europe Gmbh The presentation aims to share how the new interlayers developments fit with the new construction challenges. Specifically in the field of safety, security, decorative and sound dumping issues. There are a growing number of interlayers for laminated glass aiming at meeting the evolving needs of architects and specifiers. This presentation describes thru some case studies which interlayers have been adopted in according to the specific requirements of these iconic projects. How those interlayers expand design possibilities, raise safety standards, provide new solutions. Standard PVB is still used in more than 70% of the application. Its primary function is to enhance safety or security performance of the glazing and at the same time improve the acoustic and UV protection performance in single and double glazed units. In the last years were developed structural Interlayers which are basically divided into 2 families: Inoplast interlayer, Stiff PVB (low plasticizer) which increased even more the design possibilities as: • Transparency • Splinter protection • Impact resistance • Residual capacity after breakage • Noise protection • UV light control • Design

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Kuraray Europe Gmbh

Introduction Laminated-Safety Glass is widely used in architectural market. The requirements are challenging more than ever. The architectural market demands more and more the use of glass in construction that withstands human and load impacts and harsh climates, comfort and aesthetics. Superior structural performance can be obtained using laminated glass fabricated with interlayers. Enhanced post glass breakage characteristics increase safety factors for performance in case of accidental glass breakage.

Celebrating 25 years of GPD in Finand

types of overhead glazing include canopies installed over the front door or entrance to a building.

Glass Fins The trend to open design invites more glass and less visible framing and structural support, with an increasing structural role for advanced laminated glass. Glass Fins provides support and backup structure for structural glass designs and to prevent buckling of the structural glazing.

Screens & Louvers Applications Façade & Curtain wall Today’s facades are engineered to deliver not only aesthetically pleasing and energy-saving daylight, but also increased safety, durability and design freedom. The façade of a building is often the most important from a design perspective, as it sets the tone for the rest of the building. When glass is used as the façade, a great advantage is that natural light can penetrate deeper within the building. The façade transfers horizontal wind loads that are incident upon it to the main building structure through connections at ﬂoors or columns of the building.

Balustrades & Railings When used in glass railings, balustrades and partitions, laminated safety glass helps keep people in safe places, while adding daylight, maintaining open views, and preventing injuries related to sudden glass failure. Open edges, ﬁxturing, and outstanding structural performance are among the advantages of railings made with interlayer.

Acoustic Glazing Acoustic interlayer is a PVB film with outstanding sound protection properties. Compared to a glass assembly containing standard PVB film, the same assembly containing acoustic interlayer achieves improvements in sound insulation of up to 3 db. The production process for laminated safety glass containing acoustic interlayer is just as efficient and simple as for standard architectural glazing products. Laminated safety glass produced with acoustic PVB has outstanding product properties in terms of safety, long-term stability, lightfastness and appearance.

Roof & Overhead Glazing In architectural terms, overhead glazing or roof glazing is deﬁned as glazing that has the potential to fall on breakage, causing safety and other related concerns. The glass is normally positioned over space that is occupied by humans. Examples of overhead glazing include roofs and skylights, as well as sloped overhead glazing. Other

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Glass louver consists of parallel glass panels set in a frame. The louvers are locked together onto a track, so that they may be tilted open and shut in unison, to control airﬂow through the window. Main purpose of a louver: to form an outer skin for solar shading purposes. Typically, the glass panes can rotate to control the sunlight / shading. Screen constructions also exist, whose primary function is to provide partition glazing (exterior and interior applications).

Floors, Stairs & Bridges Worldwide, there is an increasing trend in the use of glass in both flooring and stairs in residential (private) buildings, commercial (offices) buildings and retail outlets. This trend is being driven by the increased desire to provide more open plan, unique, stylish designs. For load-bearing safety glass floors and stairs, laminates made with interlayers offer an extra level of deflection strength and structural integrity.

Windows & Doors More and bigger visible areas are requested by the market and windows and doors play a big role. As for the facade, a great advantage is that natural light can penetrate deeper within the building.

Conclusion Architects & Speciﬁers are continuing to improve freedom of design and reaching more and more tight norms/ codes through new interlayers for safety glazing developments which is a continuous improvement to follow new construction market needs in terms of safety, security, comfort and aesthetics.

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Sustainable facade design

Sustainable facade design for glazed buildings in a blast resilient urban environment

Guido Lori, Permasteelisa Group. Colin Morison, Colmor Consulting, Martin Larcher, European Commission, Joint Research Centre. Jan Belis, Ghent University KEYWORDS blast, facades, resilient, MDOF, dissipative, balance

Ultra Thin glass – Arup, BIG Architects In facade construction the glazed elements have always been considered the most critical components for the minimization of hazards during a blast event. In today’s blast events, terrorists have changed their mode of action and targets where the glass performance is weak have become even more of a concern. Therefore counter-terrorism offices (such as in the UK) have been introducing design guidelines for crowded places, making a compromise between safety and sustainability. This paper describes how it is possible to achieve a resilient urban environment, where glass is still the dominant element of the architectural scope. The protection of buildings against explosive events is not standardised like the general structural building procedures in Europe [1]. The EUROCODES only contains some procedures concerning the protection against internal explosions. The protection against explosive events is in general undertaken for specific threat scenarios by numerical simulations together with or supported by experimental trials. The façade is the first building component impinged by the blast wave and its behavior makes the difference in terms of building response and number of injuries during a bomb attack. Several buildings can suffer “facial” damages during a blast event; the most part of them are subjected to indirect loading. For public interest a first level of blast enhancement would be important for all the buildings, in the areas of the world with high risk. At this purpose counterterrorism offices are releasing guidelines for safe use of materials and components. Guidelines sometimes limit application of glass, when related to blast enhancement [2]. However a certain degree of blast enhancement is always applicable, once the dominant engineering problem is understood, assessed and possibly upgraded. Resilience can be achieved preserving at the same time the major façade requirements, in terms of aesthetics, energy efficiency, comfort and other daily demand. After bomb attacks against soft targets in UK and US during the 90’s, curtain wall behavior under blast loading has been investigated through an intensive experimental campaign. Since the first outcomes, the resistance of the curtain wall facades appeared surprising [3], especially when subjected to low/mid threats, expected as more probable on a building when it is not a direct target of the bomb attack. This type of threats is also affecting the major area damaged during

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a blast event and is of primary importance when resilience plans are developed for a certain risk area. The available best practices have been strongly influenced by the military applications and still today the reference hazard scenario has not been properly updated. It is not just a lack for the right simulation of the typical hazard façade conditions, but it has a strong impact in design/calculation methods too. For instance into the typical sequential design methods, the façade is analyzed by means of numerical model sequence, each simulating one or more façade components. Sequential methods are in general not capturing the proper façade behavior, because for instance they neglect the deformability of the framing when the glazing behavior is assessed. In curtain wall design the deformability has an important effect in extending the life of the intact glass phase, favoring the 1 way spanning mode of deformation rather than the 2 way spanning, while this effect is somehow negligible for typical window design. An example of sequential design is given by the maximum capacity loading (also known as balanced design). Under that approach it must be proven that framing and connections are capable to withstand the load from the glazing (maximum capacity), as if the glazing fails under a load higher than expected, framing and connections must not fail, structural integrity being preserved. Usually the glazing is analyzed by a Multi DOF approach, under the hypothesis of rigid frame. This is on the safe side (although uneconomical) against the real coupled behavior glazing/frame. However the estimated mullion behavior could be not on the safe side, as for instance the real behavior could preserve the glazing intact status, giving higher impulse edge reactions on the mullion if compared with the broken status, got by means of the rigid support hypothesis. This can occur especially for low/mid levels (first level of threat) of blast loads. The use of the sequential approach could be detrimental under those scenarios, as it moves the design towards a general upgrade of glazing thickness and mullion inertia. On the contrary the target should be to couple the glazing with the weakest mullion allowed by conventional load design, in order to extend as much as possible the life of the glass and then reduce the hazard level. This design approach is that one proposed by the authors, by means of a flowchart described as “balanced design chart” into an approach called “true balanced design”, exactly in op-

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Sustainable facade design

position to the classical sequential balanced design approach. Interesting option into this approach will be the integration in façade of dissipative components, which can absorb energy in excess with respect to the maximum absorbed by the glazing/ frame system. The dissipative component, for instance at the bracket level, is another fundamental element for the facade dynamic equilibrium. When the dissipative principle is activated under the blast loading, the force remains constant for a defined plastic deformation of the bracket and the inertial effect of the full façade movement freezes the stresses on the façade components, allowing a reduction of the glazing and mullion deformation for the same glass thickness/mullion inertia combination. In order to extensively apply a true balanced design approach in façade enhancement, a powerful and accurate calculation tool should be available, with sustainable computational effort within a typical design process. The finite element method (FEM) allows simulating the behavior of structures under different loadings [4]. It can be considered the referenced method for dynamic analysis too, but for several reason its adoption is difficult in practical project design. On the other side Single Degree of Freedom (SDOF) methods of dynamic analysis are a traditional way of undertaking a fast but approximate analysis of the dynamic response of a member or system. In the 1950s, early numerical analysis by Newmark [5] produced charts of elastic-plastic response that could be applied to ductile systems such as steel beams and RC beams and slabs. The Equivalent SDOF method used energy equivalence to calculate transformation factors for loading, resistance and mass and later for damping. The availability of nonlinear FE allowed glass panes under blast loading to be analyzed dynamically by SDOF. Moore [6] produced deflection and stress curves for large deflection glass panes of various aspect ratios and Morison [7] proposed an elastic-plastic PVB material model which produced a pressure-deflection curve. Subsequent analysis has shown this material model to be a good approximation of the PVB interlayer performance in blast trials [8]. 2DOF analysis can be extended into a Multi DOF analysis by including supporting transoms and mullions loaded by reaction from the glazing, and brackets loaded by reaction from the transoms and mullions. Previous Multi DOF models were developed by the authors in order to assess the deformability contribution of bracket and mullion on the glazing behavior [9], including up to five degrees of freedom and considering simply supported mullions. By the proposed model extension, further degrees of freedom can be considered, each one for any surface area. The constraint function Ð of the frame is expressed in terms of n angles Ði, representing for each surface area the relative slope of the mullion from transom to transom and giving in this way the 1 way spanning deformation of the glazing for that surface area. The application of the virtual work principle requires the knowledge of the constraint functions for glass and framing under dynamic conditions. The common assumption followed for the glass is that under a certain center deflection, the dynamic constraint function matches the static

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Celebrating 25 years of GPD in Finand

one with the same center deflection. The same principle has been applied to the frame constrain function, which can be found by means of the static function by the same combination Ð(Ð1,Ð2,.. Ðn). The authors have already undertaken sensitivity of the SDOF for variable glass thickness and blast loading [10], showing that higher modes of vibration can have a contribution on the peak of the glass deflection of around 5% in the typical range of the blast load duration t and first natural period of the glass T, even if for small load duration (highly impulsive loads) and large natural period (tall and narrow glass, with large aspect ratio) the error can be even higher than 10%. The proposed extended Multi DOF model results in errors consistent with the typical level of accuracy of the SDOF approach and has shown far superior estimations in comparison with sequential method and in general good accuracy against reference FEM analysis results. Similar outcomes have been derived by the back-calculation from a series of experimental full scale open air arena testing. Further research will be conducted on the impact of the optimized reaction time histories on the design of local slab and in general about secondary and primary building structures. REFERENCES [1] Larcher M; Arrigoni M; Bedon C; Van Doormaal A; Haberacker C; Hüsken G; Millon O; Saarenheimo A; Solomos G; Thamie L; Valsamos G; Williams A; Stolz A. Design of blastloaded glazing windows and facades: a review of essential requirements towards standardization. Advances in Civil Engineering 2016. [2] Measures to improve the blast resistance of glazing, CPNI EBP 01/14: April 2014 [3] PSDB Notes on Design for Glazing Protection, Home Office, Police Scientific Development Branch, 2004 [4] M. Larcher, G. Solomos, Folco Casadei, and N. Gebbeken. “Experimental and numerical investigations of laminated glass subjected to blast loading”. International Journal of Impact Engineering, 39:42–50, 2012 [5] Newmark N M. “An engineering approach to blast resistant design”, American Society of Civil Engineers Transactions, Paper No 2786, Vol 121 p45, 1956. [6] Moore D M. “Proposed method for determining the glass thickness of rectangular glass solar collector panels subjected to uniform normal pressure loads”, JPL Publication, Pasadena, CA, October 1980. [7] Morison C “Response of glazed facades to blast loading”, MSc dissertation, U of Westminster, 1999. [8] Morison C, Zobec M, Franceschet A. “The measurement of PVB properties at high strain rates, and their application in the design of laminated glass under bomb blast”. ISIEMS 12.1, Orlando Fl, 2007. [9] Zobec, M., Lori, Lumantarna, Ngo, T., Nguyen, “Innovative design tool for the optimization of blast enhanced façade systems“ , Journal of façade Design and Engineering, vol.2 n.3-4, 2015 [10] Lori G., Zobec, M, Franceschet, A., Manara G., “The behavior of facades due to blast loads. A single degree of freedom performance evaluation approach”, Glass Processing Days, 2009, Tampere

Winter 2017 | Intelligent Glass Solutions | 101

Celebrating 25 years of GPD in Finand

Transparent Collaboration

Miguel Ángel Ruiz Pedro Rodrigues Martifer Metallic Constructions. Facade Contractor. KEYWORDS Structural glass • Large panes Double skin • Glass ﬁns

BANCO POPULAR HQ - AUDITORIUM, MADRID (SPAIN) ABSTRACT The use of structural glass in architecture has always been a challenge since the beginning of time, and despite Peter Rice’s first great achievements in this field in the middle of the 20th century, it is something that we should always strive to improve and seek greater achievements. If we add the desire to achieve the largest possible glass dimensions that can be made with the greatest transparency (see figure 1) then the challenges are significantly big. The concept of architectural design in the Auditorium of the New Headquarters of the Banco Popular in Madrid (Spain) was made by Arquitectos Ayala and ENAR as part of the Architects team. It is a question of combining all the previously mentioned ingredients to achieve the Architect and Facade Consultant intention of creating a double skin glass with the fewest visible pieces as possible in order to eliminate the visibility of any supporting structure. By this way, we are able to create the illusion of a fully “transparent box” for the enjoyment of the occupants who use this facility.

INTRODUCTION This document refers to a small explanation of the Auditorium execution process from the design and development of the technical solution, testing, manufacturing,

to its final execution. As usual in this type of singular projects, the design and calculations were essential to ensure the correct functioning of the facade system. Obviously, to build a glass box, the first objective was to define the structural concept of the double skin and run the calculation of all elements that form part of the entire system. Once the calculations were done and the compositions of the glasses were defined, the next step was to test a real scale mock-up in a certified laboratory to check its feasibility. If the results were as expected at structural and performance level, then the manufacturing and assembly phase can begin. Although the manufacture required great control to avoid problems of lamination and finishing due to its large format, the biggest challenge was the installation, this was due to the fact that the Auditorium is located between two large buildings with limited access to the glazing logistics and resources.

TYPICAL DETAILS After reviewing the original drawings and specs, the initial idea was clearly deﬁned. The exterior and interior glass should have a dimension of 2,600 x 9,500mm (width x large) and both surfaces should be separated 700mm with a 7,980mm glass ﬁn inside between them. A top gap (1800mm) was required to allow the passage

Figure 1. Architectural concept at initial design stage. Interior view

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Transparent Collaboration

Figure 2. 3D Image for small visual mock up to show the double skin of glazing

Celebrating 25 years of GPD in Finand

Figure 3. Auditorium structure, supports, dimensions and section

After all the calculations (SLS and ULS), the ﬁnal glazing compositions are: Dimensions

Composition

Heat Treatment

Outer pane

2600x9500 mm

10/2,28/10

Heat-strengthened

Inner pane

2600x9500 mm

10/2,28/10

Heat-strengthened

Glass ﬁn (typical bay)

700x7980 mm

10/1,52/10/1,52/10

Heat-strengthened

Glass ﬁn (corner)

1000x7980 mm

10/1,52/10/1,52/10

Full tempered

Table 1. Final glazing composition of two bespoke rail systems for future maintenance (see figure 2 above). All the glasses are composed with low iron glass to focus the transparency and laminated with standard PVB. The inner and outer glass panes are fixed in its lower part in the 3 axes and supported on a hidden metallic substructure. However, in the upper end the glass is fixed in axes (x, z), leaving free movement in the vertical (figure 3 above). In relation to the glass fin, it is embedded 280mm into its lower part by the use of screws, using polyamide, nylon and resins in the holes for proper operation. STRUCTURE AND ANALYSIS The design calculation of the agreed solution was made by Autodesk Robot Structural Analysis, SolidWorks Simulation (figure 3) and SJ Mepla. Initial conditions: Wind pressure: Wp=Ws= +–0,6 KPa (typical bay) and Ws= -0,9 KPa at corners (first 2,6m) Horizontal live loads: 1,6 KN/m (h=1,2m) Maximum displacement for outer/inner panes: L/65 or 50mm Upper slab maximum deflection: 32mm

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On the other hand all the joints required to bond the glass panels were designed and tested for chemical and firm adhesion between all the elements. For example, the joint with the vertical aluminium profile (figure 4), the top horizontal edge and a special vertical join at corners. In figure 4 above we can see that the bonding process of the aluminium profile to the glass fin was made in the

Figure 4. Joint between the main glasses (outer/inner pane and glass ﬁn)

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Celebrating 25 years of GPD in Finand

factory, while the strings that join the side of the glass with the metal profile itself is made with the same material, but on site. The design allows applying the silicone with contact between only two surfaces. Finally the finishing silicone is applied also on site. As required by the Architect all aluminium profiles are hidden creating the desired effect of a completely “transparent glass box”.

Transparent Collaboration

different “cube faces” were different we had to double check the levelling of all supporting structures in order to ensure a perfect fit of the glass. Once the overloads of the areas near the final site were verified, the zone was modelled to analyse the installation tolerances for the future movements. It was very important because in addition to the glasses dimensions, each unit weighs more than 1,200 kg.

TESTING OF PROTOTYPE Due to the large dimensions of this façade it was required to create a special chamber (the ﬁrst of its kind in the Iberian Peninsula) to perform the laboratory tests (see ﬁgure 5). Test for air permeability, water tightness, resistance to wind load and impact resistance were done according to the current regulations standards. As expected, the results were satisfactory (see table 2)

INSTALLATION As mentioned before, the installation process was a big challenge (see ﬁgures 6 and 7). A detailed 3D assembly sequence study was done to ensure proper execution of the work. Due to the fact that the bottom level of the

Figure 5. Image during the installation phase at the laboratory

FUTURE OPPORTUNITIES FOR CONCEPTS DEVELOPMENT Looking to the future, it would be interesting to collaborate in a new project with bigger panes. Why not use 20mx3.51m pieces to build a new glass box? Another aspect is the use of titanium inserts to make the joints between glasses, although sometimes the use of these pieces, even punctual, may not follow the architectural concept of a self-supporting transparent structure without visible metallic proﬁles.

ACKNOWLEDGEMENTS Many thanks to our Client, Banco Popular, for the trust shown to Martifer during the development of project, and for believing in this type of singular construction. To Ayala Arquitectos and ENAR for designing this type of structure which is so different and special that creates great technical challenges that force us to innovate and ﬁnd solutions each day. We are also extremely grateful to BOVIS for the coordination during all the execution of this very special project. Thank You!

Figures 6 and 7. Installation process and general view with some of the pieces protected

Summary table of test results: Test Method

Classiﬁcation

Results

Air permeability

UNE 12153:2000

UNE 12152:2000

Class A4

Water tightness

UNE 12155:2000

UNE 12154:2000

Class R7

Resistance to wind load

UNE 12179:2000

UNE 13116:2001

Class 600 Pa

Impact test

UNE 13049:2003

UNE 14019:2004

I3 (interior)

UNE 12600:2002 Table 2. Test results and regulation applied.

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Celebrating 25 years of GPD in Finand

Sika Services AG

Structural Silicone Joints in Cold-Bent SSG Units

Viviana Nardini Florian Doebbel Sika Services AG – Building Systems & Industry KEYWORDS Structural Silicone • Cold-Bending, SSG Units • Curved • Warped

Sika Services AG – Building Systems & Industry Abstract Use of cold-bent and warped glass units in unitized curtain walling has been getting a state-of-the-art application for the last years. This creates special demands on appropriate design of glass units and frame members as well as on the elastic and load-bearing bonding joints in Structural Sealant Glazing applications. Depending on the approach of producing and installing these units as well as the geometrical boundary conditions, the structural silicone joints are affected by additional permanent load reactions and joint movements next to regular loading. Due to the warped or curved shape of the units, signiﬁcant changes in load distribution, load sharing and stiffness can result and even load peaks in the elastic silicone joints can arise. This paper summarizes technical requirements and engineering rules as well as design aspects enabling appropriate design and calculation of structural silicone joints in cold-bent SSG units. Reﬂecting a reliable safety concept and the expected life cycle of these loadbearing bonding joints is part of the approach.

1. Introduction The demand of emulating nature’s complex and ﬂowing layout by using curved or even biomorphic design combined with transparent panels and valuable surfaces is an increasing trend replacing conventional straight-lined and sharp-edged geometry in architectural design. While traditional design limits the architectural freedom as well as the value of recognition and building identity, curvilinear design offers an unlimited variety of custom-made and nonrecurring building shapes. Designs supported by advanced planning processes and computer-aided tools, which had been reserved for automotive industry, have been transferring to buildings and facades. Considering that sophisticated designs of typical industrial products are implemented to a serial production using complex and dedicated tools, it’s the façade engineer’s and manufacturer’s challenge to properly realize custom-made and mostly nonrecurring shapes within the given economical, technical and regulative restrictions and within acceptable timeframe. Based on the fact that facades as face and skin of a building have to comply with functional, protective and ar-

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chitectural demands, glass and glazed units as a main part of the envelope have to comply with these demands, too. That means, glass units and their restraints have to ﬁt curvilinear designs, what pushes the demand on curved and warped single glass, laminated glass as well as insulating glass units replacing more and more ﬂat and polygonally installed or even cylindrically shaped glass units.

2. Curved Glass Elements Manufacturing Curved architectural glass can be manufactured in the façade markets according to three main methods. Hot bending During thermal shaping of glass, a variety of cylindrical and spherical as well as asymmetrical and irregular bending shapes with smaller and larger bending radii can be achieved within the technical limits. The advantage lies in the exact and permanent setting of the required shape in the manufacturing process. The pre-sized float glass sheets are heated to just over the transformation temperature. Based on the desired geometry and manufacturing processes, the softened glass either can settle in the prefabricated and fire-resistant mold (bending by gravity) by its own weight or is shaped through mechanical molding. The resulting glass strength, fracture pattern and tolerances in the finished state are largely controlled by the cooling process itself. Glass coatings can’t be applied on the shaped glass surfaces, after hot-bending. Due to the manufacturing process, required reflective of low-e coatings must be thermally stable and suitable for tempering. PVB interlayers, applied between two bent glass lites after the hot-bending procedure, must be chosen in respect of thickness and material properties so that tolerance between the bent lites can be accommodated without constraining stresses. The assembling of the insulated glass unit or its connection to the façade element must also be stress-free. But especially for heavily curved units increased climatic effects, affecting the hermetically sealed cavity, as well as formation and distribution of reaction forces which differ significantly from the situation of flat glazing and non-curved insulating glass units have to be taken into account.

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Cold-bending or cold-warping of flat glass elements If the use of slightly curved and uniformly or symmetrically bent geometries is required, the use of cold-bent glazing is usually recommended. Since cold-bent glazings are no longer heated up to the glass transformation temperature, the surface quality of smooth and leveled produced float glasses is maintained. Local distortions, as they arise during the transformation process of hot-bending, can be excluded during cold-bending. Tempering, frit-coating, printing and film coating can be done with standard equipment in flat condition without compromising properties, quality and variety. However, value and shape of the cold-bent unit are limited. Permanent glass stress, which is caused by cold-bending, has to be limited through imposed displacement and glass thickness. Heat-treated glass products are normally used to provide an adequate resistance to counter permanent stress conditions. Cold-bending by lamination Glass units cold-bent by lamination are similar to the condition of glasses, likewise cold-bent glazings. In contrast to normal cold-bending, the required bending shape is applied during the autoclave process using a corresponding bending device or mold on the overall package of glass and interlayers, before they are joined together to form a single unit. Thermal treatment in the autoclave is done far below the glass transformation temperature and thus has no effect on the properties of the glass products and existing coatings. Depending on the interlayer used, a specific elastic back flipping as well as a time-, load- and temperature-dependent creep of the organic interlayer have to be considered for the curved and laminated unit. The use of glasses bent by lamination is particularly advantageous when the use of laminated glass is required for other reasons too, or if an exact cylindrical or spherical design is targeted, which differs to a limited extent from the natural bending shape of the glazing. Cold-bending by lamination can significantly reduce permanent effects on laminated glass edges and glass supports. Visual (aesthetic) demands, technical feasibility and actual availability usually drive the selection of the specific manufacturing process. In addition, regulative requirements, consultants’ agreement and appropriate balance between costs, benefits and risks are important factors to be accounted for the selection. Even if curved glass units are becoming standard elements of architectural design and project designers and glass and façade producers are getting more and more experienced, curved glass elements are still not standardized. As a consequence, related technical and economic risks lay on decision-makers and investors.

3. Structural Silicone Joints in Cold-Bent SSG Systems Cold-bending and cold-warping of facade elements mainly consists in cold bending of monolithic glasses,

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Sika Services AG

laminated glasses or insulating glass units as well as the frames that retain them in the structure after they have been produced and assembled in a flat state. This technique drastically reduces the production costs of the curved façade elements and is very beneficial in projects where serial repetition is limited. In the majority of international projects where transparency and flowing layouts are emphasized by curvilinear shapes, fixing of appropriate cold-formed glass panels in Structural Sealant Glazing (SSG) units is achieved by the load-bearing bonding provided by structural silicone adhesives (Figure 1). Their approvals and assessment are controlled in the European area by EOTA ETAG002 [3] and American area by ASTM C 1401 [4]. EOTA ETAG 002 [3] refers to exposure of the structural silicone joints to short-term wind loads (dynamic tensile stress), to cyclic thermal expansion between different components (dynamic shear stress) and to permanent dead load transfer (static shear stress). A similar concept is covered by ASTM C 1401 [4]. Stress from cold-bending of glass units and façade elements is not explicitly considered in [3] or [4] and thus requires careful and comprehensive engineering analysis.

Figure 1: Typical SSG system.

Figure 2: Tensile stress distribution in SSG-joints of coldwarped units according to Beer [2]: stress peaks at the corners based on non-linear FE analysis (left) and simpliﬁed uniform stress distribution (right).

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Sika Services AG

Significant reactions, which arise in the elastic silicone joints due to cold-bending, are: Permanent tensile loads – Stressing the SSG joint to bond the glass element to the frame (Ftot – Figure 4) as well as the IG joint of any insulating glass units which is cold-bent (Fout – Figure 4). The permanent tensile stress is caused by restoring forces (back flipping) of displacement elastically applied on the flat produced glass unit and need to be properly withstood over the entire life cycle. Figure 2 shows the visualization of the distribution of the tensile stress caused by restoring forces of a cold-warped unit according to Beer [2]. High stress peaks at the element corners can be identified with precise simulation of the reaction forces in a non-linear finite element model based on hyper elastic bulk elements representing the elastic adhesive joints. Consideration about Mullins effect could be called upon to evaluate such stress peaks in the joints: the mechanical response of the silicone adhesive and its stress-strain curve depends on the maximum loading previously experienced (Figure 3) and can be idealized as an instantaneous and irreversible softening of the stress strain curve that occurs whenever the load increases beyond its prior all-time maximum value. Non-linear elastic behaviour prevails when the load is lower than a prior maximum, while Mullins softening is a viscoelastic effect mainly driven by friction of fillers and sliding of polymer chains. Therefore, it can be argued that short-term wind load superimposed to tensile load due to cold bending can produce a softening of the material and stress reductions. Nevertheless, the extent to which stress peaks can be regarded as a temporary effect and can be compensated due to relaxation in favor of a uniform stress

Figure 3: Mullins effect on structural silicone Sikasil® SG-500.

Figure 4: Long-lasting effects on elastic adhesive joints by SSG bonding and insulating glass edge seal: Flat situation (left). Insulating glass and frame bonded in a ﬂat state and subsequently warped (center). Bonding of ﬂat produced insulating glass unit on pre-shaped frame members (right). (© Sika)

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Celebrating 25 years of GPD in Finand

distribution requires further investigation or a materialdependent clarification. Under the assumption of a uniform distribution as shown in Figure 2 on the right, the restoring force of a representative glass unit could also be calculated or experimentally determined using a dummy load, which could then be distributed as an idealized triangular load on the edges of the panel. Depending on the relevant needs, the resistance of the elastic adhesive joints against the permanent load can be adjusted by increasing the joint bite as necessary. Permanent shear movements – affecting the SSG joint to bond the glass element to the frame (sjoint – Figure 4) as well as the IG joint of any insulating glass units which is cold-bent (sseal – Figure 4). Under the influence of shear forces caused by geometricrelated and reverse movement imposed to the bonded surfaces, possibilities to control the stress level in the joint without a significant increase in its thickness (clearance of bonded surfaces) are limited. However, while the restoring forces acting out-of-plane of the cold-bent and cold-warped unit can only be reduced by decreasing the glass stiffness (glass thickness, glass size, elastic / viscous and thermo-elastic interlayers) or by using mechanical restraints, there are possibilities for actively influencing the reduction of shear movements in the elastic adhesive joints by evaluating different cold-bending procedures: • A very effective option to remove the permanent shear stress in the SSG joints due to cold bending is using hot-bent frame members, so that only the glazing is cold-bent. The glass unit can be cold-bent on the preshaped frame and temporarily fix to it by mechanical devices; application of the SSG-joints can follow. After the adhesive is completely cured, mechanical devices can be removed. The introduction of significant shear movements in the SSG joints (sjoint – Figure 4) is permanently prevented. • Another option to limit the permanent shear stress in the SSG joints due to cold bending is to temporary fix by mechanical devices the glass unit to the frame and cold bent them; after that, application of the SSG joint can follow. When adhesive is completely cured, the mechanical temporary devices can be removed. Permanent tensile stress will arise in the SSG joints; shear stress will arise in the SSG joints too, but its duration will be limited to the timeframe from production to installation, when cold-bent shape will be restored. If one considers that the level of shear movements does not only depend on the displacement needed to set the curvature but also on the geometry of the bonded components, it is obvious that the system design itself could have important influence on limiting permanent forces in the adhesive joints without further increasing the effort and complexity of factory production and bonding of façade elements.

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As shown in Figure 5, the degree of shear deformation is significantly influenced by the cross-sectional height of the bonded components and does not just depend on the displacement and the curvature of the cold-bent element. That means, the larger the cross-sectional height of frame and glass, the bigger the offset of the bending axis and surfaces of the bonded components and the bigger the reverse movement 6 of the bonding surfaces, whereas the accommodation of large shear movements within the allowable stress can only be realized by a massive increase of the adhesive joint thickness. In other words: permanent shear stress in the SSG joints can be significantly reduced by increasing the thickness of the structural silicone joint but also by a massive reduction of the cross-sectional height of the bonded components. This can be achieved e.g. by: • Using flat slim frames mechanically connected to a load bearing frame in such a way that free in-plane relative displacements are allowed (Figure 6). The flat slim adapter frame can be bonded to the glass unit at the factory site; after joints are completely cured, application of required out-of-plane displacements for cold bending can occur on site. • Using flat slim adapter frames which are bonded to the flat glass units at the factory site. After joints are completely cured, the bonded assembly can be cold-bent and fixed to a pre-shaped load bearing frame on site.

4. Permanent Effects on SSG Joints due to Cold Bending After determining the permanent load reactions, which are created in the elastic adhesive joints by cold-bending

Figure 6: Slim adapter frame to minimize effects of imposed shear movements due to cold-bending.

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Sika Services AG

or cold-warping of SSG units, the influence on the loadcapacity and durability of the structural silicone bonding needs to be evaluated. ASTM C 1401 [4] requires a strong limitation of permanent load effects, such as dead-load shear, to maximum 1psi (0.007MPa), while European EOTA ETAG 002 [3] only gives partial guidance on how to proceed. The definition of a creep test under long-term shear in superposition with cyclic tensile loading in Section 5.1.4.6.8 of [3] helps to get an indication about the longterm performance of the structural silicone. It defines the influence of permanent shear stress on dead-load unsupported systems, what means that the total weight of the glass is permanently transfrered by the structural silicone only. In addition to the creep test, which requires massive restriction on residual shear deformation after complete unloading besides an adequate material resistance under permanent loading, a creep factor of at least 10 is defined by [3] in the same section. The allowable shear stress has to be reduced by the creep factor in addition to the dynamic safety factor when the elastic adhesive joints are required to take the total dead load. The procedure defined in [3] can be applied to the evaluation of elastic adhesive joints which are used in cold-bent SSG units only to a certain extent. Indeed, while creeping test defined by [3] analyzes the combined effect of permanent shear load and temporary or dynamic tensile load, the effects of cold-bending produces permanent tensile loads and limited-in-distance shear movement. Considering this, one could take over the approach of [4] and reduce the allowable stress for dynamic tensile loading by an additional creep factor gc ≥ 10, with respect to the permanent action of the restoring forces and in order to permanently restrain the cold-bent and structurally bonded glass units. For evaluating permanent shear movement [3] has no practical approach since the use of the allowable static shear stress for this case would hardly lead to applicable joint thickness, in most cases. Moreover, it must be considered that the imposed displacement is indeed permanent but limited in magnitude, as related to a onetime setup and does not increase over the life cycle. Thus the risk of creep is structurally non-existent. Instead, a

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Sika Services AG

Celebrating 25 years of GPD in Finand

tended design values could be proposed to include shear strength accounting for relaxation effects to use when shear movements are imposed to joints, but no permanent shear loads to be transferred. For an entire evaluation of the structural silicone joints, the inﬂuences of wind, live loads and climatic effects must be taken into account too. Short-term and permanent load combinations should be deﬁned and combination of utilization levels out of existing stress and allowable stress should be evaluated with regard to relevant load directions and durations.

process must be found which eventually deﬁnes a maximum permissible level for the relaxation of permanently distorted joints. In this context, it should be mentioned that an allowable relaxation of the adhesive joint in shear direction must not have effects in a reduction of material resistance. For this purpose, following tests have been performed on structural silicone adhesives: • Lap-shear tests with structural silicone joints loaded up to failure as per following conditions: - Lap-shear samples tested up to failure at 23°C / 50% relative humidity with no preliminary loading and used as reference - Lap-shear samples tested up to failure at 55° C / 95% relative humidity with no preliminary loading - Lap-shear samples loaded for 91days under different levels of imposed shear movements and tested up to failure at 55° C / 95% relative humidity. Comparison of results obtained from the above lapshear samples shows that the ultimate strength of the joint does not decrease, if adhesive has previously experienced an imposed deformation up to maximum 30% design load set by [4]. • Creep tests according to EOTA ETAG002 [3], associated to permanent loading from 10% to 60% the design load deﬁned by [3]. The test shows that up to maximum 30% the design load set by [4], joint movements are stabilized and do not increase further after 91 days, although residual deformation are recorded (Figure 8). Based on above considerations and test series, exProduct

A variety of criteria exists for optimizing the bending process of curved glass elements in façade applications, which take into account different design and manufacturing process and needs. Besides the preferably discussed visual, technical and cost-driven aspects, influences on the joint design of SSG units must also be considered. How the negative influence of large shear deformation can be significantly reduced on permanently loaded structural silicone joints through a clever system design and use of leaner adapter frame is shown in Section 3. Furthermore, the relationship between EOTA ETAG 002 [3] and the stress of elastic adhesive joints in cold-bent units is established in Section 4. The observation shows that the existing approvals of structural silicone adhesives on the basis of [3] and [4] cannot or can only be consulted to a limited extent for the verification of coldbent SSG units. More extensive research and guidelines are needed for evaluation and calculation methods of cold-bent elements, as well as definition of meaningful allowable stress.

6. References [1] Dodd, G.; Thieme, S.: Comparison of curved glass and cold bent panels. GPD Glass Performance Days 2007, S. 83-86. [2] Beer, B.: Structural Silicone Sealed Cold-Bent Glass – High-Rise Projects Experience Leading to a New Design Concept. GPD Glass Performance Days 2015, S. 235-240. [3] EOTA ETAG 002-1, Structural Sealant Glazing Systems Part 1: Supported and Unsupported Systems, 1998. [4] ASTM C1401, Standard Guide for Structural Sealant Glazing, 2014.

EOTA ETAG 002

m des (MPa)

o des (MPa)

(MPa)

G (MPa)

(MPa)

o', relax (MPa)

Sikasil® SG-500

0.14

0.105

0.0105

0.50

0.014

0.0315

Sikasil® SG-550

0.20

0.13

0.013

0.63

0.020

0.039

Sikasil IG-25

0.14

0.101

0.010

0.73

0.014

0.030

Sikasil IG-25 HM Plus

0.19

0.13

0.011

0.86

0.019

0.033

® ®

Table 1: Extended range of design values based on EOTA ETAG002 igsmag.com

Winter 2017 | Intelligent Glass Solutions | 109

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SOON!!! IGS Spring 2018 issue

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• Executive Boardroom Commentary • World Exclusive Interviews with industry ﬁgures of distinction • We go from the general sector of Safety & Security and move to the particular concern of glass & ﬁre • Facing THE HOTTEST topics in architectural glass and facade engineering Copy Date: 9th February

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Ian Ritchie Architects is delighted with the outcome of the Sainsbury Wellcome Centre and the wonderful working relationship with those involved with the faĂ§ades, and would like to thank them. Whether it is the innovative translucent wall with its opening ZLQGRZV DQG ORXYUHV UHĂ HFWLQJ VXQVHW RU WKH WUDQVOXFHQW SL[HOV dancing in the wind, our architectural ambition to create an ephemeral white building has been achieved. Ian Ritchie Architects enjoys, with passion, composing art with science to achieve wonderful environments for people. Having established a reputation for faĂ§ade design in glass and metal the practice continues to innovate when appropriate and intelligently.

Â´,DQ 5LWFKLH $UFKLWHFWV KDV DQ H[WUDRUGLQDU\ DELOLW\ WR EULQJ together the arts of design for architecture and engineering and to dissolve the boundaries of the intellectual and physical representation of them. 7KURXJK WKH SUDFWLFHÂˇV DUFKLWHFWXUH H[SHULPHQWDWLRQ DQG collaboration are encouraged with a genuine spirit of technical and social ambition. The practice shares its ideas freely and commits to them wholeheartedly. It regularly operates beyond the conventional professional understanding of an architectural practice, notably in its collaborations with industry in developing innovative products and techniques.â&#x20AC;? SIR DUNCAN MICHAEL, FORMER CHAIRMAN, ARUP

Ian Ritchie Architects Ltd 110 Three Colt Street London E14 8AZ T . +44(0)20 73381100 F . +44(0)20 73381199 www.ianritchiearchitects.co.uk mail@ianritchiearchitects.co.uk

INTELLIGENT GLASS SOLUTIONS Winter 2017

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James O’Callaghan CEO & Founding Partner Eckersley O’Callaghan Engineers 236 Grays Inn Road, London, WC1X 8HB United Kingdom Tel: +44 (0)20 7354 5402 www.eocengineers.com E-Mail: james@eocengineers.com Elke Harreiss Exhibition Director FENSTERBAU FRONTALE NürnbergMesse GmbH Messezentrum, 90471 Nürnberg, Germany Tel: +49 (0) 9 1186 068323 www.frontale.de E-Mail: Elke.Harreiss@nuernbergmesse.de Lewis Wilson Marketing Director IGS Magazine www.igsmag.com E-Mail: lewis@igsmag.com Stephanie Akkoui-Hughes CEO & Founder AKKA Architects Linnaeusstraat 2C, 1092 CK Amsterdam, The Netherlands Tel: +31 (0) 20 301 4018 www.akkaarchitects.com E-Mail: Stephanie.hughes@ akkaarchitects.com Dr Jochen Mignat Dr Mignat PR Am Hexenpfad 11, D-63450 Hanau, Germany Tel: +49 (0) 6181 507 9122 E-Mail: j.mignat@mignat.de Stanley Yee, LEED Dow Corning Corporation Corporate Center, 2200 W Salzberg Road, P O Box 994, Auburn MI - 48611, USA www.dowcorning.com E-Mail: Stanley.yee@dowcorning.com

112 | Intelligent Glass Solutions | Winter 2017

AUTHORS DETAILS WINTER 2017 Rouven Seidler Seen GmbH Laengacherstrasse 10, 3367 Thorigen, Switzerland Tel: +41 (0) 71 351 2596 www.seengmbh.com E-Mail: rs@seengmbh.ch Marcin Brzezicki, PhD Wroclaw University of Technology Faculty of Architecture Ul.Prusa 53/55, 50-317 Wroclaw, Poland www.arch.pwr.wroc.pl E-Mail: marcin.brzezicki@pwr.wroc.pl Paul Bastianen PBH Publications Damloper 69, NL-4902CE Oosterhout, The Netherlands Tel: +31(0) 643 888 728 E-Mail: p.bastianen@planet.nl Sophie Pennetier Mark Bowers Guillaume Evain Arup 13, Fitzroy Street, London W1T 4BQ, United Kingdom www.arup.com E-Mail: sophie.pennetier@arup.com E-Mail: mark.bowers@arup.com BIG Architects Kløverbladsgade 56, 2500 Valby, Copenhagen, Denmark www.big.dk E-Mail: guillaume@big.dk Benjamin Beer Meinhardt Façade Technology PO Box 282478 Gold & Diamond Park, Building 5, Unit 125-126, Sheikh Zayed Road, Dubai, UAE Tel: + 971 (0) 4 380 9422 M: + 971 56 265 7364 www.mfacade.com E-Mail: Benjamin.beer@mfacade.com

ENAR Envolventes Arquitectonicas C/Chile 10.28290Las Rozas, Madrid, Espana Tel: +34.916.303.770 www.envolventesarquitectonicas.es Graham Dodd Fellow Arup Arup 13, Fitzroy Street, London W1T 4BQ, United Kingdom www.arup.com E-Mail: graham.dodd@arup.com Fabio Favoino Luigi Giovannini EOC Engineers 236 Grays Inn Road, London , WC1X 8HB Tel: +44.(0)20.7354.5402 www.eocengineers.com Sandro Casaccio Kuraray Europe GmbH Philip-Reis-Strasse 4, 65795 Hattersheim am Main, Germany Tel: +49 (0) 69 305 35840 www.kuraray.eu E-Mail: sandro.casaccio@kuraray.com Miguel Angel Ruiz Pedro Rodrigues Martifer Metallic Construction Zona Industrial, Apartedo 17, 3684-001 Oliveira de Frades, Portugal www.martifer.com E-Mail: info@martifer.pt Viviana Nardini Florian Döbbel Sika Services AG Tuffenwies 16, CH-8048 Zürich, Switzerland Tel: +41 (0) 58 436 5287 www.sika.com E-Mail: nardini.viviana@it.sika.com E-Mail: doebbel.ﬂorian@ch.sika.com

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