Passive House Plus (Sustainable building) issue 44 UK

Publishers Temple Media Ltd

PO Box 9688, Blackrock, Co. Dublin, Ireland

t +353 (0)1 210 7513

e info@passivehouseplus.ie www.passivehouseplus.co.uk

Editor Jeff Colley jeff@passivehouseplus.ie

Reporter John Hearne john@passivehouseplus.ie

Reporter Kate de Selincourt kate@passivehouseplus.ie

Reporter John Cradden cradden@passivehouseplus.ie

Production / IT Dudley Colley dudley@passivehouseplus.ie

Accounts Oisin Hart oisin@passivehouseplus.ie

Art Director Lauren Colley lauren@passivehouseplus.ie

editor’s letter

Close your eyes and imagine your least favourite part of your least favourite song. And now imagine the record is scratched, so it’s playing in a hellishly unending loop. You’re welcome. My hope is that I’ve set a sufficiently low bar and that the broken record I’m about to play will seem like sweet relief.

I’ve lost count of the times over the years that I’ve argued in this letter that we must adopt evidence-based approaches if we are to make buildings sustainable. It may seem to suck the romance out of life, but quantification is essential to this, and for that to happen we need metrics. Those metrics must be robust, and they must be understood. Parroting numbers, without understanding and contextualising what they mean, is futile.

found a – hopefully – engaging way to explain what may seem unspeakably dull or obtuse: the thermal comfort assumptions in energy performance calculation methodologies.

Let me try to convey the meaning in this case: You design a house to achieve an A rating, and ensure that it’s built in accordance with all the requirements to hit that seemingly superlative standard. The house is marketed as an A-rated home, and the lucky homebuyers move in, expecting to reap the benefits of a cosy home with low energy use. Then the utility bills arrive, and the trouble begins.

Design

Aoife O’Hara aoife@evekudesign.com | evekudesign.com

Contributors

Lenny Antonelli journalist

Hamish Bresnahan Alexander Symes Architect

Toby Cambray Greengauge Building Energy Consultants

Chris Croly BDP

Simon Jones Air Quality Matters

Marc Ó Riain doctor of architecture

Peter Rickaby energy & sustainability consultant

David W Smith journalist

Jason Walsh journalist

Print

GPS Colour Graphics www.gpscolour.co.uk | +44 (0) 28 9070 2020

Cover

Lambeth Enerphit

Photo: Timothy Soar

It’s challenging attempting to publish meaningful articles about sustainable building – articles that we hope will help inspire and inform our readers to make new and existing buildings fit for this new Anthropocene era, this confluence of climate emergency, biodiversity emergency, housing emergency, geopolitical emergency, bloody omni-emergency. Our task is to take complex subjects – in a range of related areas where continuous research is advancing humanity’s understanding at the leading edge – and make it somehow digestible, explicable so that people can have the confidence to apply these learnings on actual buildings. It’s not just a matter of keeping up with the latest evidence. It’s about explaining it.

If you’re explaining, you’re losing, according to B-movie actor and deregulation poster boy Ronald Reagan. But we must resist the Gipper’s advice, trust that our readers are sufficiently resolved to hear us out, and explain ourselves in the simplest way possible, short of dumbing down.

So how does this manifest itself, in practical terms, and how does it relate to the earlier bleatings about metrics? In this issue, it’s in having the audacity to publish a feature article on an EN standard, and trusting that our readers will stay awake and understand the significance of the issue, and find that we’ve

The energy crisis sparked by Russia’s invasion of Ukraine has helped bring matters to a head, but the problem is simple: the A-rating for the home was built on a model which assumes miserly heating levels – a whole house average of less than 15.6 C for sixteen hours per day for one notional house which complies with Ireland’s nearly zero energy building (NZEB) standard. And the UK assumptions while more generous, were still woefully inadequate.

The problem is that it’s not enough to have metrics. We need realistic targets too, and we need to ensure building users understand what they’re getting. We said we’d give you an A-rated house. We didn’t say it would be a comfortable house.

Worst of all, energy performance is one of the areas where we have the best understanding of the evidence. For over 30 years, the passive house standard has shown a route to essentially solve the energy, comfort and indoor air quality issues – though in this issue you’ll find a Dublin office building showing an intriguing alternative approach – so we have no excuse for not getting this right. True, there are many other areas of sustainability where we still have a way to go in terms of establishing, bedding-in and clearly explaining evidence-based metrics. But time is of the essence: we must play the notes we do know and learn the ones we don’t, before the record stops.

Regards, The editor

Publisher’s circulation statement: Passive House Plus (UK edition) has a print run of 9,000 copies, posted to architects, clients, contractors & engineers. This includes the members of the Passivhaus Trust, the AECB & the Green Register of Construction Professionals, as well as thousands of key specifiers involved in current & forthcoming sustainable building projects.

Disclaimer: The

in Passive House Plus

CONTENTS

BIG PICTURE

This issue features Pepper Tree Passive House, a small secondary dwelling attached to a young family’s home in the Australian Illawarra region.

NEWS

WorldGBC launches green building policy principles for governments, Scotland to mandate passive house for new homes, and experts say TrustMark’s new Licence Plus scheme undermines retrofit standards.

COMMENT

Dr Marc Ó Riain writes about the emergence of the passive house standard; and while poor practice remains stubbornly persistent in parts of the industry, understanding why and how this persists could be a catalyst for change, argues Dr Peter Rickaby.

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CASE STUDIES

Visionary vernacular

Passive inspired Dumfries home puts users first Can a low energy building be truly sustainable if it doesn’t fully consider its occupants needs? The latest offering from one of Scotland’s leading green designers uses passive house knowhow to signal the way to pragmatic, modest, occupantcentric architecture.

Military precision

West Country barn conversion brings low carbon comfort for army family

Designing a building to the passive house standard for the first time is one thing. But trying to do so when the client is a soldier, the design must accommodate the frame of a barn, and you’re straining to get it built precisely on schedule, during a pandemic, is quite another.

Modern love

1960s modernist gem gets Enerphit treatment

Where does the balance lie between conservation of buildings, energy and nature?

One deep retrofit to a London modernist house may point the way ahead, bringing light, form and avant garde energy performance to old ideas about contemporary living.

58

Adaptation sensation

Landmark Dublin building pioneers dynamic adaptive comfort approach

Sometimes a building comes along that asks challenging questions. Chris Croly, building services engineering director of BDP, describes one such example – a building designed to tackle the specific energy profile of offices, while trialling an innovative, dynamically-controlled approach to adaptive comfort.

INSIGHT

Cold comfort

Are Ireland and the UK’s energy ratings predicated on cold homes?

Passive houses aside, attempts at low energy building have a long and inglorious history of using more energy than predicted, with a key reason being “comfort taking”, where occupants take back the benefit of energy efficiency by cranking up the thermostat. But is it rather that energy ratings are assuming miserly heating use –and temperatures that fail to meet the requirements of a new EN comfort standard?

MARKETPLACE

Keep up with the latest developments from some of the leading companies in sustainable building, including new product innovations, project updates and more.

What goes around comes around

Why the history of refrigeration points to the future of heating

As efforts to decarbonise buildings gain pace, heat pumps powered by an increasingly clean grid are looking like an irresistible force. While reducing emissions from operational energy use rightly remains front and centre, embodied carbon is the next target – including the heat pump’s refrigerant. Toby Cambray goes back to refrigeration’s beginnings to find a route to a low carbon future.

BIG PICTURE

PASSIVE & ECO BUILDS FROM AROUND THE WORLD

While genuine efforts to address aspects of sustainability are becoming common in construction projects, all too often those efforts remain couched in an oil age mindset – typified by the likes of a remotely located passive house McMansion with two SUVs in the driveway.

But sometimes a building comes along where, rather than feeling incongruous, energy targets like passive house are manifestly functioning as part of a well-rounded conception of sustainability, using resources sparingly to deliver a home that is at once modest and delightful – a blueprint for an architecture fit for the Anthropocene.

Hamish Bresnahan of Alexander Symes Architect explains the practice’s work on one such project: Pepper Tree Passive House

1. Introducing Pepper Tree Passive House

Pepper Tree Passive House is a small secondary dwelling, attached to a young family’s home in the Australian Illawarra region, perched on a steep site and elevated into the canopy of the site’s 60-year-old pepper tree. Built to the passive house standard, sustainability is at the core ethos of the project – embodied between the natural material palette, high performance design and strong biophilic connection.

The ambition of this project was to do more with less. While light touches to the existing home were made to improve its thermal performance, building the new secondary dwelling to the passive house standard has created a future proofed refuge to escape to in future peak temperature days.

2. An ambitious upgrade

Adam Souter approached Alexander Symes Architect with the ambitious project, looking to upgrade his family’s Unanderra home as well as use the opportunity to showcase the technical expertise of his emerging construction firm, Souter Built.

Adam is passionate about the future of sustainable housing in Australia, trying to implement sustainable change to the way we build, one house at a time. A certified passive house tradesperson, Adam and his partner Ame Rooke-Jones wanted to create a sustainable, healthy space to raise their three kids.

3. Preserving nature

From the outset, the intention of the additions to the home was to protect the pepper tree and explore the potential of high performance, future-proofed technologies that are respectful of our natural environment and a step towards regenerative architecture.

4. Work / life balance

The brief was developed to envision the secondary dwelling as a 24-hour space; used as a home office by the family’s growing business during the day, and a short-term stay cabin at night that would give visitors an experience of the higher quality of space that the passive house standard affords, all while creating a future-proofed studio with western views to Mount Kembla and the treetops outside. Pepper Tree Passive House gives the clients a perfect space to work while being able to create a distinct separation between work and home life, without the lengthy commutes and empty building hours experienced in a traditional workplace model.

5. Year-round views

The west-facing views over the suburb’s tree canopy toward Mount Kembla are one of the key elements of the site. The timber alu clad triple-glazed full height windows ensure that these views are enjoyed year-round without the significant compromises to thermal comfort that would be experienced with a typical window system, thanks to the harsh western afternoon sun of the local climate.

Subservient to the existing pepper tree, the U-shaped form of the new building creates a high ratio of external envelope to internal volume which proved difficult to achieve airtightness, especially given the project was Souter Built’s first passive house project. They succeeded though, achieving 0.51 ACH @50 Pa on the final blower door test.

Photos: Barton Taylor

Section BB

Section AA

6. Seeking approval

There was an extensive coordination process with the local council, because of the unique form and building makeup that isn’t commensurate with standard secondary dwellings.

Under current legislation, the size of secondary dwellings is measured to the external wall finishes. Although the detached studio is under 60 sqm in internal floor space, there was great difficulty in getting the council to approve the proposed works as the highly insulated walls meant that they were thicker than a standard build, thereby increasing the perceived footprint. This is something that architect Alexander Symes still believes needs addressing, as the current legislation punishes higher performing building envelopes.

7. Subtle upgrades

Although the clients were also looking to upgrade their Illawarra home, the existing house functioned well for their needs already.

Instead of extensive alterations and additions, light touches were made to the existing home to upgrade its thermal performance – including new external insulation and timber cladding, repainting the existing concrete tiles lighter to reduce heat gain and the addition of a 12 kW building-integrated photovoltaic pergola.

Wrap around decks were added to the existing home to strengthen its ability to connect with the gardens, and improve the usability of the entire site. New recycled timber fencing to the front garden provided space for chickens and an edible garden.

8. Celebrating the natural environment

From the project’s outset it was critical for the design to use both materials and landscaping in a way that strengthened the biophilic connection to the pepper tree, as well as regenerate the biodiversity of the site. Despite the small building footprint, it was critical to the project’s success that the site’s natural environment was dis-

turbed as little as possible.

The building’s two cantilevered wings each host an extensive roof garden, filled with a variety of drought tolerant native plants, collecting excess rainwater to be used in the dwelling, and helping to blend the building into the site.

The choice of charred Shou Sugi Ban

timber cladding behind the existing street trees adds to this effect, while removing the need for ongoing maintenance over the material’s lifecycle. Internally, timber products with non-VOC finishes were used, reducing total embodied energy while still providing a warm material palette.

9. Reclaimed materials

To reduce the amount of new materials used and total embodied energy of the project, Adam constantly saved materials that otherwise would have gone to waste as part of the work of Souter Built, stockpiling a catalogue of reclaimed materials to be used on the project.

Adam’s constant innovation in holistic material approach is exemplified throughout this project, such as salvaging the structural timber from the demolition of a 100-year-old home in Bondi (which became Pepper Tree Passive House’s external staircase) as well as ensuring all leftovers from Souter Built’s concrete pours of the last few years were poured into empty buckets (which became the external pavers for Pepper Tree Passive House).

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10. Form and function

The northern wing houses the living, office and kitchen spaces with a breakfast bar, carefully framing a view of Mount Kembla. Recycled sandstock bricks line the floor and wall area where direct sunlight from the northern highlight windows projects during winter, acting as a thermal battery.

The more private southern wing contains the bedroom, laundry and bathroom, ensuring the total volume of the building is only as big as it needs to be to protect the existing pepper tree. The floating deck between the two wings has been carefully scribed around the pepper tree, providing a meditative retreat immersed in the tree canopy.

11. Performs as designed

A life-cycle assessment was conducted that showed despite the higher amount of embodied energy associated with passive house construction, due to the small, high performance building envelope, low-embodied carbon material selection and significant on-site generated & exported renewable energy, the building’s environmental footprint is 64 per cent less than a comparable built-as-usual home in the same climate zone.

The use of Shou Sugi Ban recycled hardwood cladding means that no re-oiling of the timber is required, and protects the timber from pests and rot.

Between the passive house standard and the 12 kW photovoltaic system installed, the whole home uses 94 per cent less grid energy than a comparable five-person home in the same climate zone. This ensures the young family has energy security, and is not susceptible to grid electricity market increases. The home will also be a bastion against unpredictable future climate peaks – during the recent cold snap the space was a comfortable 20 C internally while outdoor temperatures were below 1 C (without using any internal heating).

New Licence Plus scheme undermines retrofit standards, experts say

TrustMark defends scheme & says it creates a pathway to PAS 2035

By Lenny Antonelli

Leading retrofit experts are concerned that TrustMark’s new Licence Plus scheme for domestic retrofit installers and contractors threatens to undermine years of work to improve retrofit standards.

TrustMark launched Licence Plus in September last year to “enable more quality retrofit energy efficiency improvement installations to be made to the millions of homes across the UK”. The scheme is intended to demonstrate the “competency and quality” of participating installers to deliver retrofit.

However, key figures in the retrofit sector expressed concern that the introduction of the scheme would put the existing BSI Retrofit Standards Framework, and in particular the PAS 2035 standard, on the backseat and pose a threat to retrofit quality.

Some members of the BSI Retrofit Standards Task Group that Passive House Plus spoke to felt that Licence Plus had been introduced following political pressure to develop a less onerous alternative to PAS 2035.

PAS 2035 was developed by the BSI to help safeguard homes and occupant health from the consequences of bad retrofit, following the 2016 Each Homes Counts review into retrofit failures. Licence Plus appears to omit a number of PAS 2035 quality control elements, such as the need for a risk assessment, retrofit design and post occupancy evaluation.

“We know from retrofit failures that remediating the consequences can take a long time and cost much more than it would have done to do the work properly in the first place. Failures also erode public confidence in the retrofit industry,” said Peter Rickaby, former chair of the BSI Retrofit Standards Task Group. “In this context, it is depressing to see that with the Licence Plus scheme TrustMark is abandoning nearly all the public protection mechanisms enshrined in PAS 2035 in the face of in-

dustry push-back and political expediency.

It is difficult to avoid the conclusion that TrustMark has lost sight of its mission and is not to be trusted.”

Meanwhile Julie Godefroy, CIBSE’s head of net zero, said: “Licence Plus does not require compliance with PAS 2035/2030. Instead, it risks reducing the drive for upskilling and sending confusing and contradictory messages to homeowners. Developing skills and competences is an investment which will return multiple benefits. Government and public bodies procuring works should demonstrate their commitment to developing a skilled and competent retrofit industry, through supporting PAS 2035/30, in order to deliver safe, comfortable, and low energy and low carbon homes.”

Passive House Plus understands that many members of the task group did not hear about Licence Plus until it was presented to them one week after it was first launched on the TrustMark website, and felt undermined after years of work to develop retrofit standards.

“It's disappointing to see that Licence Plus appears to be a move away from a whole house approach to retrofit,” said Marianne Heaslip, technical director of People Powered Retrofit. “Retrofit requires joined up thinking if we're to avoid some of the disasters of the 2010s. This is why PAS 2035 is so valuable. Rather than trying to ignore the complexities involved in retrofit, I hope the industry changes tack and instead embraces this challenge. Not only because this is necessary technically, but also because that's how we'll get new people involved in rewarding roles and achieve the skills and understanding we need to do this work well.”

A ‘transition’ to PAS 2035

Responding to questions from Passive

House Plus, a spokesperson for TrustMark said that Licence Plus would enable installers who have demonstrated their competence “to engage in a transition adoption of whole house fabric-first retrofit”.

“The Licence Plus Scheme (LPS) does not replace or compete with PAS 2035 but aims to support new businesses with a positive adoption of aspects of its principles and work within a consumer protection and oversight process so that they can more readily transition towards it,” the spokesperson said. However, critics said there is no clear mechanism for how this transition is to take place.

The TrustMark spokesperson said that businesses can only become Licence Plus registered through their scheme provider (i.e., a certification body or trade association), which “builds in another layer of trust”.

The Licence Plus scheme will use the Reduced Data Standard Assessment Procedure (RdSAP) process to produce an Energy Performance Certificate (EPC) for each dwelling. “This helps to identify staged improvements that can be incorporated into the homeowner’s project to create a plan of future improvements,” the spokesperson added.

He said Licence Plus would “create a pathway for tradespeople to engage with oversight, audit, and compliance processes where they might not have previously done so, and added that, “TrustMark is pleased to be working with the Retrofit Standards [sic] groups to look at how we can achieve the best outcomes to transition to a place where the PAS 2035 ideal is realised.”

However, some members of the BSI Retrofit Standards Task Group pointed out to Passive House Plus that TrustMark did not work with the group in drawing up the scheme. •

Scotland to mandate passive house for new homes

Scotland’s minister for zero carbon buildings is proposing to make the passive house standard, or a new Scottish equivalent, the minimum energy efficiency standard for new build homes from the end of 2024.

It follows Alex Rowley MSP’s proposal last year for a Domestic Building Environmental Standards Bill, which aimed to introduce the passive house standard into Scottish law, and which received support from across the political spectrum.

The Scottish government has now said it will give effect to the proposal through its own legislation by the end of 2024. Patrick Harvie MSP, Scotland’s minister for zero carbon buildings and a Scottish Green Party MSP for Glasgow, said: “I look forward to working with Mr Rowley – and with colleagues across parliament – to continue supporting improvements and enhancements to energy and environmental standards across our new housing stock, and delivering our vision to make all homes in Scotland warmer, greener and cheaper to run.”

The Green Party in Scotland supports the SNP-led government through a power sharing deal. The shared policy programme between the two parties, published in September 2021, expressed “explicit support for passivhaus and equivalent standards” and says that all buildings that apply for a building warrant from 2024 onwards must use “zero emissions heating as the primary heating source and meet significantly higher

energy efficiency standards”.

Passive House Plus understands that Alex Rowley, a member of Scottish Labour, will be involved in the drafting of the bill, and that the Passivhaus Trust has also been consulted.

A consultation on Mr Rowley’s proposal last year received 629 responses, with 80 per cent being fully supportive, 13 per cent partially supportive and only six per cent opposed.

“A move to the Passivhaus ‘gold standard’ for all new-build homes would be radical, ambitious, practical and forward-thinking,” Rowley wrote when proposing his bill last year. “It would future proof homes and prevent them from having to be retrofitted in the near future, upskill the construction sector and make Scotland a leading player with exportable skills and knowledge.”

One group who voiced their objection, though, was Homes for Scotland, a representative body for the country’s home building sector. The group’s submission said that the proposal was “not required” as the “current direction of travel” in the building regulations would improve energy efficiency and thermal performance. The group said that proposing new standards without allowing adequate time for transition would lead to a “significant reduction” in the number of new homes built in Scotland.

The Royal Incorporation of Architects in Scotland, meanwhile, was partially supportive and called for a “flexible Scottish equivalent to the Passivhaus Standard”. It said that any

new energy efficiency standards should be implemented through the existing framework of building regulations.

Writing in the construction magazine Project Scotland, solicitors Keith Emerson and Andrew Leslie cautioned that two years “was not a lot of time to formulate new standards, educate all parts of the industry on it and implement these changes.”

They also wrote that building to the passive house standard typically costs 5 to 10 per cent more. However, while specific research for Scotland is not available, a 2019 paper by leading passive house expert Dr Shane Colclough and chartered surveyor Martin McWilliams concluded that the extra cost for a developer to build a three-bed dwelling to the passive house standard compared to the 2012 English building regulations was £1,984, or £1,368 for a new build social house, figures closer to one per cent of building costs. Previous research by Colclough and colleagues found that the extra cost of building a passive house in Ireland, where minimum energy efficiency regulations for buildings are tighter, was as low as 0.1 per cent.

The Passivhaus Trust, meanwhile, said in 2019 that “best practice” passive house construction would cost 8 per cent more, but that this could be reduced to four per cent once the standard is adopted at scale. n

Passive house isn’t just about efficiency – it’s about social justice

The potential of the passive house standard to change the world isn’t restricted to tackling climate change – it’s about social justice too.

Speaking at the 26th International Passive House Conference in Wiesbaden, Passive House Plus reporter Kate de Selincourt spoke about the role of highly energy efficient buildings in enabling lower-income communities to live in a healthy environment. "So much of the passive house is about health and well-being," said de Selincourt, who had researched the human consequences of the energy crisis in the Cold Proof series of articles in issue 43 of Passive House Plus.

De Selincourt told the conference that a growing number of British people are unable to heat their homes properly. Low-income families and elderly people have been living in winter in cold and damp buildings with room temperatures of 15 C – and sometimes even below 10 C, leading to enormous suffering and health threats. De Selincourt also told the audience about the gratitude of residents when they move into homes that meet the passive house standard. "The heat stays in the house for a long time, and the demand for heating energy is generally low. The whole lives of these people are changed," de Selincourt said. A separate series of lectures was devoted to the topic of social housing, with projects from around the world.

The conference covered other benefits of passive house projects, such as delivering good indoor air quality in buildings with vulnerable occupants such as schools and health care buildings, and protecting the power grid against overloading.

Around 600 international participants attended the three-day conference, which was held in Wiesbaden and online. Excursions took visitors to impressive projects such as the passive house district Bahnstadt Heidelberg and the first certified passive house hospital in Frankfurt.

"It is motivating to see that a high level of energy efficiency is having a ripple effect around the world. Here we have heard about impressive large projects, also in the area of energy retrofits, which are changing lives for the better for inhabitants in the long term," said Jan Steiger, member of the management board of the Passive House Institute.

Nora Steurer of the Global Alliance for

Buildings and Construction (GlobalABC), a network associated with the United Nations, pointed out that global CO2 emissions in the building and construction sector rose by five per cent in 2021 compared with the previous year. The decarbonisation of this sector must therefore be "enormously accelerated." This requires a structural change, according to Steurer. Passive House Institute founder Prof Wolfgang Feist and director Dr Benjamin Krick highlighted the urgency of the conference’s theme, Efficiency NOW! "Unless the heating demand of buildings is reduced, the power grid won't suffice if the majority of our buildings are equipped with heat pumps", explained Krick.

Delegates also learned of Enerphit retrofit projects in Germany, Ireland, Spain, Poland and Denmark, and large scale projects such as the 18-storey Ken Soble Tower in Hamilton, Canada, which is providing 146 healthy and affordable apartments with low energy costs to the predominantly elderly residents. In northern Mexico, where summer temperatures can reach 52 C, one project provided crucial information on the feasibility and cost-effectiveness of Enerphit retrofits in emerging economies. A workshop on the EU outPHit project focused on large-scale and fail-safe deep retrofits using prefabricated components. Municipalities were invited to attend a workshop specifically tailored to their needs, which also presented the outPHit concepts for quality assurance in retrofits to the Enerphit standard. •

with us.

It is always a pleasure to work with the Passive House Plus team. They provide a wealth of information, support and time to provide the best advert. Launching a new product is never easy, but in the space of only two months we’ve received over 150 enquiries through two issues of the magazine and all have been very fruitful. We have been quoting straight after the magazine is out. A lot of the customers enquiring have genuine current projects and this is reflected in how many respond to our follow ups.

It is no doubt in my mind that this team are one of the best I have dealt with out of the many publications we use. They deliver and they deliver quality!

- Elizabeth Assaf, owner, Urban Front

To enquire about advertising, contact Jeff Colley on +353 (0)1 2107513 , or email jeff@passivehouseplus.ie

at the 26th International Passive House Conference about the human consequences of the energy crisis – and how the passive house standard can help.

(above) Passive House Plus reporter Kate De Selincourt spoke

WorldGBC launches green building policy principles for governments

The World Green Building Council (WorldGBC) has launched a set of principles aimed at guiding national governments to develop effective building policies and programmes to accelerate a decarbonised future.

The principles, developed by WorldGBC with its network of 75+ green building councils, were released ahead of the G7 ministers’ meeting on climate, energy and environment on 15–16 April, and take into account sobering analysis from the latest Intergovernmental Panel on Climate Change (IPCC) report, and the conclusion that there is a rapidly closing window of opportunity to implement policies that will keep the world within the 1.5 C warming limit.

Many of the priority topics for the G7 ministers meeting can be addressed by buildings — from achieving both energy security and net zero, to advancing the transition to circular economies. Worldwide, buildings are responsible for 37 per cent of energy-related carbon emissions and 34 per cent of energy demand. With such a significant environmental and carbon impact, leaders and policymakers must recognise the built environment as a key agent of change to close the 1.5 C gap.

WorldGBC and its network have launched “Global Policy Principles for a

Sustainable Built Environment”, to support policymakers around the world to adopt a holistic approach to built environment sustainability, and ensure that new and updated policies and legislations deliver the transformative action needed to reach the Paris Agreement and the UN’s Sustainable Development Goals.

The principles are structured around seven key focus areas: carbon, resilience, circularity, water, biodiversity, health, equity and access. These areas are supported by detailed policy levers to show how they can be effectively implemented through regulation, information and incentives. Despite being the largest contributing sector to carbon emissions, the building and construction industry is still not on track to achieve total decarbonisation by 2050, meaning the gap between actual climate performance of the sector and its pathway to decarbonisation is widening.

This creates a dual challenge for the built environment — with markets in Asia and Africa expecting their building stock to double by mid-century. Meanwhile other regions are grappling with the challenges of renovating energy inefficient buildings.

Cristina Gamboa, CEO, WorldGBC, said: “Our sector is in a strong position to deliver resilient development that integrates

mitigation and adaptation measures, whilst also addressing other pressing societal issues, including energy security, resilience, health and equity. In this global stocktake of the Paris Agreement year, and ahead of countries submitting updated nationally determined contributions (NDCs) in 2024, it is crucial that political leaders take bold actions to strengthen and implement building policies that deliver transformative change.”

By supporting the delivery of these principles, governments will be sending a clear signal to the market that decarbonised built environments are a priority, therefore enabling industry to deliver more innovative solutions. But governments must take a holistic approach, embracing public funding and influencing financial investment decisions and tools that consider carbon mitigation, resilience and green buildings. WorldGBC and its green building council network invite governments to use “Global Policy Principles for a Sustainable Built Environment” as a tool to review and update existing legislation; as well as offering their support within a local and global context.

Download the report here: https://tinyurl. com/WorldGBCreport. •

Must listen: Zero Ambitions Podcast

Over the past two years Passive House Plus editor Jeff Colley has been moonlighting as co-host of Zero Ambitions, a weekly podcast that wrestles with the challenge of how to deliver the scale and ambition of decarbonisation and sustainability in buildings required to avoid a hellish future. The focus is very much on keeping listeners engaged and informed – with a necessary dose of gallows humour.

Jeff’s co-hosts are user experience experts Alex Blondin and Dan Hyde (co-founder of Passive House Plus’s progenitor, Construct Ireland), who help to ensure the podcast couches the technical minutiae that Jeff loves in a manner that might chime with different

kinds of users – designers, tradespeople, policymakers and building users.

Some recent highlights:

• Learning from our mistakes: looking back at ten retrofits, ten years later, with retrofit pioneer Marion Baeli (PDP, Passivhaus Trust)

• Systems design for passive houses, radon research as a proxy for ventilation, and some further education. With Dr. Barry McCarron (PHAI, CREST)

• Passive house can lead to more than just houses: community engagement, control pathologies, and propagating systemic change. With Helena Fitzgerald (Department of Economics at the University of Limerick)

• Unconventional approaches to space heating: infra-red, ceramics, and the necessity for good design. With John Morehead (Wain Morehead Architects)

• EPCs are just a ritual (pt. 1): fundamental flaws in how we assess energy performance and how we got here, with Adrian Leaman and Bill Bordass (UsableBuildings.co.uk)

• Retrofit, energy ratings, and improving Europe's energy performance, with Ciarán Cuffe MEP

The podcast is available wherever you listen to podcasts. But you can find all ninety-five episodes here: https://tinyurl. com/zeroambitionspod. •

Book review Show Me the Bodies: How We Let Grenfell Happen, by Peter Apps

Review: Simon Jones

porter, Peter Apps, is a forensic review, as it stands today, of the evidence presented at that inquiry. And it is an indictment of the entire sector.

But it is the account from those that were there that night and the stories of the community that lived in Grenfell that lifts this book to another level. Each chapter starts at a point in time in the evening and sets the scene as the disaster unfolds, followed by powerful personal testimonies and stories of the lives it touched and destroyed.

It is an emotional rollercoaster of the shock of the events, the heartache of the lives it ruined, and anger at a system that let Grenfell happen. I found myself shaking my head in disbelief one minute, taking a minute to compose myself another (that's crying like a baby), to wanting to break something.

of June 2017, our government got what it had asked for”.

From the first chapter, this book smacks you in the face and doesn’t let up. It’s a story of loss and unbelievable bravery, it’s a story of neglect and obfuscation at a grand scale and ultimately a story of failure to protect the vulnerable including families and children.

It’s a story that everyone involved in the built environment should read, think about for a while, read again, and imprint in their memory.

The entire industry needs to ask itself the question, what kind of culture creep takes a company to a place that these found themselves in? And what systems can it put in place to make sure it never happens again?

On 14 June 2017, 72 people needlessly died in what was to become the UK’s worst housing disaster. For anyone watching at the time, as flames ripped up the sides of the high rise building in West London, it was clear something had gone horribly wrong, and what followed in the years afterward through the subsequent inquiry and investigations, sent shockwaves through the sector – shockwaves that should change everything.

I, like many, followed the inquiry as it happened, facilitated largely by the excellent reporting of Peter Apps, deputy editor at Inside Housing, a publication with a focus on social housing.

I was shocked by the testimony, and being from industry, was particularly interested in how something so extraordinarily flammable could find itself on the outside of any building, let alone a tower block. The answers, as they were coming out from the inquiry at the time, were explosive.

This book "Show Me the Bodies: How We Let Grenfell Happen", by the same re-

But this disaster was foretold by many, from industry experts to the residents of the flats themselves. Warnings to the local authority about the state of disrepair of many of the safety systems that would ultimately hinder rescue efforts on the night, went unheeded.

It’s hard to even begin to explain the industry's part in what led to the products being used on the high-rise, which ultimately turned Grenfell into a towering inferno. With one manager's response to questions about the products fire safety, years beforehand, saying they could “go fuck themselves”. An employee of another describing a test on its product as a "towering inferno", buried the testing and marketed it for use on high-rise buildings. There were failings, all the way to the top of the system itself, with the false reliance on declining deaths by fire used as an excuse for inaction and the citing of unreasonable burdens and costs to industry. As one senior civil servant put it when pressed to justify its failure to tighten fire safety rules, “show me the bodies.”

As Apps notes in the book, “on the 14th

And as a society, this book asks uncomfortable questions of us all. Ultimately, how did we let Grenfell happen? And this time, this time, will we learn the lessons? •

ABOUT THE REVIEWER

Simon Jones has been in building services, air quality and the built environment for nearly two decades and has consistently been a voice for better standards and approaches in the industry. He has built up a reputation of integrity and knowledge in that time across the ventilation and indoor air quality sector.

Cynicism and inspiration

In spite of everything we know about how to build and retrofit high quality low energy buildings, poor practice remains stubbornly persistent in parts of the industry. But understanding why and how this persists could be a catalyst for change, argues

Dr Peter Rickaby

Readers of this column may have detected some cynicism in recent editions. After years promoting energy efficiency and retrofit, a little cynicism seems appropriate, especially about the chances of the UK government rising adequately to the challenge of climate change. However, my cynicism is more broadly based than that: it has been reinforced by recent projects and by Peter Apps’s book Show me the Bodies, about revelations from the Grenfell Tower enquiry. Apps paints a picture of an industrial culture of lying, cheating, and minimal compliance

and reporting on defects in a block of over 250 flats in south London owned by a housing organisation. The block was designed over ten years ago by a leading housing architect and a leading M&E consultancy, who adopted the passive house standard. Unfortunately, the housing organisation chose to procure the building via design and build, from a contractor who appears to have been incompetent at best. The design air permeability was changed from 1 m3/m2h@50Pa to 4 m3/m2h@50Pa, the wall U-value as built was 40 per cent higher than specified (be-

with or avoidance of regulations, combined with government complacency and wilful inaction in the face of uncomfortable truths. In short, focusing on the bottom line and ignoring the health and safety of everyone else.

Recently, I have been assisting a couple who bought a house from a housebuilder and have never been able to heat it adequately. In winter, they wear anoraks at home, and cannot invite friends and family to visit. After years of fruitless argument between my clients and the housebuilder, we used airtightness testing and thermography to show that the house is riddled with thermal bridging and thermal bypass, and with the help of a solicitor we finally nudged the housebuilder into offering limited remedial work. Then the housebuilder argued that further thermography to demonstrate that the proposed work has been effective is unnecessary because it is not required by Building Regulations. Wait – what? This is not about Building Regulations. Does the housebuilder care so little for its customers that it couldn’t just admit that the house is not fit for purpose, apologise for the defects and promptly correct them?

Another project has involved investigating

cause wall ties and fixings were not allowed for), the windows and external doors didn’t fit properly, the never-serviced MVHR systems were the cheapest available, and the ductwork leaked. In the as-built SAP/EPC assessments the air permeability of every flat was recorded as exactly 4 m3/m2h@50Pa, a barely credible result that doesn’t seem to have attracted the attention of the building control body. Recent testing suggests that 7 m3/m2h@50Pa would have been more accurate. To compound the mess the housing organisation is now procuring remedial work through another design and build process.

Finally, my colleagues at the UK Centre for Moisture in Buildings have been receiving requests from housing organisations for training about condensation, damp and mould (CDM). Of course, we are pleased to provide such training, but it is difficult to avoid the conclusion that the sudden interest is driven by the tragic death of Awaab Ishak, the loss of £1m funding by his family’s landlords, and the consequent sacking of their chief executive. There has been mould in social housing for decades, and it has either been ignored or dealt with by blaming

residents’ ‘lifestyle’ and perhaps installing an inadequate ventilation fan. If the objective of social housing is to provide accommodation for low-income families, how can mouldy housing that they cannot afford to heat properly be considered fit for purpose? Peabody’s ground-breaking CDM strategy for Thamesmead showed five years ago that a risk-based approach and good ventilation can deal with the problem. Cynicism is not helpful, of course, unless it drives effective action. I have said before that what the building and housing industries need to help them rise to the challenge of climate change is inspirational leadership. So, to finish on a positive note, there has always been plenty of that around, even if it hasn’t been as effective as we might like. Colleagues have undertaken and disseminated research and demonstration projects, written and published guidance, developed and delivered training, contributed to reviews, written technical standards, developed and implemented improvement strategies, and delivered cutting-edge retrofit. Organisations such as the Passivhaus Trust, the Good Homes Alliance, the Sustainable Traditional Buildings Alliance, the London Energy Transformation Initiative, the Architects Climate Action Network and the amazing Make a Difference network have many energetic and inspirational members. But why is exhausting work needed to counter the lazy, complacent bottom-liners who pushback? That’s life, I guess, so I’m minded to repeat some Latin advice from my late father: “Nil illegitimae carborundum” (which, very loosely translated, means “Don’t let the bastards grind you down”). n

Dr Peter Rickaby is an independent energy and sustainability consultant, and a retrofit consultant with Savills social housing team. He helps to run the UK Centre for Moisture in Buildings at University College London, where he is an Honorary Senior Research Fellow. He is also helping Rise International with research into sustainable building materials for Lesotho. The views expressed here are his own and not necessarily those of Savills, the UKCMB, UCL or Rise International.

I’m assisting a couple who bought an unheatable house from a housebuilder. In winter they wear anoraks at home, and can’t invite friends to visit.

The road to Damascus: The Passive House Standard

Set against a 1980s backdrop of abundant, cheap, dirty energy and reckless “greed is good” free market capitalism, a quiet revolution in low energy building was brewing in Germany, as Dr. Marc O Riain writes.

All the development of active and passive low energy buildings throughout the 20th century, much of which has been discussed in this column previously, was leading somewhere. From Solar 1 MIT in 1933, through to the first ‘Zero energy house’ in Copenhagen (1974), Bentley’s double wall construction (1976), the development of heat pump technology in the Phillip’s experimental house (Aachen 1975), the discovery of thermal bridging and thermal bypass by the Princeton House Doctors (1977), and the combination of heat recovery ventilation with a high degree of tightness and super-insulation in the Saskatchewan Conservation House (1977). Pioneering projects like these provided the deep research precedents required for the development of the passive house standard by Wolfgang Feist and Bo Adamson in 1988.

The voluntary German building energy performance standard was primarily centred around passive solar, thermal comfort, super-insulation, airtightness and mechanical ventilation with heat recovery (although not exclusively), and thermal bridge-free construction. Supported by government subsidies, Bott, Ridder and Westermeyer Architects developed a four-house terrace to the passive house standard in 1990. Each unit was 156 m2 and 50 per cent of the cost of the build was met by the Hesse state government.

The standard set quantitative performance targets for designers to meet to achieve a very low whole building energy use. The system synthesized most of the previous passive strategies with MVHR into a quantifiable design process. Interestingly, active solar (potentially due to cost) was not a core part of this strategy in 1988, but later welcomed by Feist as a suitable renewable component.

The passive house is only really ‘passive’ in the sense that the design approach takes a “passive-first” approach to energy conservation, leaving the building with a small amount of fixed primary energy balance (120 kW/m2/yr) to then be met with active systems. It might be better defined as a hybridised low energy or zero energy house.

This standard attempts to isolate the enclosed habitable environment from the external environment irrespective of the building’s location, making the standard globally appli-

cable, using local climate data sets. Criticisms of some aspects of passive house highlight issues with space heating capacity in colder environments (Straube 2009) and overheating in the summer (Goncalves et al. 2022, Mitchell & Natarajan 2019, Finegan 2022).

In a similar strategy to the Lo-cal House of 1976, designers must use high performance glazing (<0.8 W/m2k) and achieve thermal bridge-free design (identified at Twin Rivers - Nisson and Dutt 1985). The standard allows for shading devices to moderate summer overheating, employing natural shading such as deciduous trees or building integrated shading (again, similar to the Lo-cal House). The highly technical system is based on knowledge of building physics, a level of sophistication or specialization not commonly found in architectural education (Tzonis 2014) and as a result not abundant in architectural practice.

By 2016, there were only 3,000 certified passive house designers worldwide, with 323 in Ireland out of 2,507 registered architects at the time (Maguire 2016). The passive house standard, and its Excel-based planning software, requires the building designer to become familiar with local climactic conditions, mechanical systems, solar heat gain calculations, and thermal bridging calculations. The key energy performance standards are 15 kWh/m2/ yr for heating and cooling demand, and/or 10 W/m2 heating/cooling load, with remaining loads attributable to lighting and process loads, leaving a total overall building primary energy demand of 120 kWh/m2/yr for all energy loads – including a significant aspect absent from national methodologies such as DEAP and SAP: unregulated (plug) loads.

In 1996, an economical planning package was developed to demonstrate payback periods based on unit costs of energy plus inflation (Passivhaus 2016). In 2011, the institute introduced a standard for building retrofit, called Enerphit. While it relaxed standards for space heating demand (25 kWh/m2a) and airtightness (1 ACH @50 Pa), the overall whole building performance remained the same (120 kWh/m2a).

Passive house is the single most popular voluntary low energy design process in the world, with an estimated 60,000 (as of 2016) certified passive houses built worldwide (Passipedia 2015). The weakness of the system is

perhaps the need for so much training and the lack of intuitive design software. For architects passive house offers a measurable, quantifiable results-based matrix for design decision-making. It offers a clear, if complex strategy, that can inform the design process.

Several factors combine to limit the standards wider adoption due to cost and time-constraints: its detailed application software (PHPP), optional use of ‘localised’ climate data and in some instances use of secondary software (Trnsys, Therm, WuFi) to validate inputs. The standard is voluntary whereas national energy performance standards are mandatory, meaning one might or not achieve regulatory compliance by meeting the standard without additional measures, further limiting practice adoption.

At a very strategic level, passive house is both an insightful and useful design approach that every architect and engineer should learn in college. It teaches us to understand aspects of the whole building as an energy performing unit. Since Tomás O’Leary’s first passive house in Ireland in 2004, the growth of the standard has been both exceptional and global, influencing the EU definition of nearly zero energy buildings (2010) and the subsequent member state adoption in to building codes.

The passive house standard has been a valuable education, policy and practice tool, that has resulted in a complete modal shift in the design and construction of our buildings, and has the ability to eliminate fuel poverty through energy conservation while mitigating CO2 released into our atmosphere. In the lee of an energy crisis we have become far more aware of the importance of energy efficient buildings and the passive house standard. n

Dr Marc Ó Riain is a lecturer in the Department of Architecture at Munster Technological University (MTU). He has a PhD in zero energy retrofit and has delivered both residential and commercial NZEB retrofits In Ireland. He is a director of RUA Architects and has a passion for the environment both built and natural.

IN BRIEF

House type: 107 m2 bungalow

Method: Wood fibre insulated timber frame infrared heating

Location: Dumfries and Galloway

Standard: AECB CarbonLite Building Standard

Heating & hot water cost: £90/month*

* Estimated space heating and hot water cost, based on Ofgem’s energy price guarantee for October 2022.

See ‘In detail’ panel for more information.

£90 per month

VISIONARY VERNACULAR

PASSIVE-INSPIRED DUMFRIES HOME PUTS USERS FIRST

Can a low energy building be truly sustainable if it doesn’t fully consider its occupants needs? The latest offering from one of Scotland’s leading green designers uses passive house knowhow to signal the way to pragmatic, modest, occupant-centric architecture.

By John Cradden

It’s been shown clearly over the last few years that passive house design lends itself relatively easily to a variety of building forms thanks to the versatility of PHPP software.

But every so often, a combination of tight budgets and less than ideal form factors present a challenge that gives even those architects passionate about the standard a reason to rethink their approaches, without jettisoning the efficiency, sustainability, and attention to detail that fully certified passive houses demand.

Beechtrees, a lovely, modest larch-clad, zinc-roofed house in Scotland built by seasoned Dundee-based passive house designer Kirsty Maguire, is one such case.

It’s built to the AECB CarbonLite Building Standard, which is based on passive house and uses the same software (PHPP), but with less onerous targets for energy performance.

Located in a rural area in the middle of Dumfries and Galloway, a large region in the southwest corner of the country, it’s an unusual and innovative build that doesn’t try to ape a traditional farmhouse, but still strongly reflects the local vernacular of metal roofs and timber cladding of the neighbour-

ing farm buildings. The inspiration Kirsty Maguire took from around the site is infectious: the link building between the living and bedroom wings has the same colouring as “a beautifully weathered barn with a rust red roof,” and a similar nearby shed.

Built for two retirees, Tony Francis and Zoe Roberts, as their forever home, it’s also single-storey, meaning it will be easier for the couple to navigate in future years. That comes at an energy cost as it increases the building’s surface area to volume ratio or ‘form factor’. Future-proofing the house to allow for the occupants’ changing needs in this case means more walls, roof and ground floor per square metre, and therefore more surfaces through which heat is lost. The form factor is also not helped by the H-shaped floor plan, designed to give the couple two courtyards.

It’s designed essentially so that the external spaces are conceived as external rooms, as the clients spend a lot of time outdoors,” said Kirsty Maguire.

The courtyards each exploit the light at different times of day, a bit like a sundial. According to Maguire, the east courtyard, opening from the kitchen, is perfect for

sitting outside with a morning coffee. As the sun moves around, it hits the south side with the pond and vegetable garden, bathing the outdoor dining table in sunlight from late morning until evening. It has a generous living space with a cathedral ceiling in the main part of the building. The

bedroom wing is similar but more private and set back, and there’s a welcoming entrance space linking the two.

What the whole space gains inside and outside as a result of this clever design is clearly worth the concession – if you can call it that – of building to the AECB CarbonLite Building Standard instead of passive house.

A quick look at the building fabric specs shows that Beechtrees has exactly what you’d expect to see in a passive house: the U-values for walls, roof, floor and windows, the thermal bridging and the airtightness, and the Zehnder heat recovery ventilation system. It also has infrared heating for the little warmth that’s required and an air source heat pump – using the ultra-low global warming potential (GWP) refrigerant R290 – for hot water.

Named after the mature deciduous trees from the site, Beechtrees is all about timber. As many trees were retained as much as possible, with the felled trees being turned into cills and shelving by a local craftsman. The building’s superstructure is timber frame, with Steico wood fibre insulation in walls and roof, and triple glazed timber windows. The project’s broader sustainability efforts extended into other materials too. Reclaimed materials are used as well, such as paviours, and the drystone dyke

was rebuilt by Tony using stone from site.

It’s reasonable to argue that if the budget was more flexible, a greater investment in wall insulation, for instance, could have brought the overall energy performance closer to the passive house standard, but other choices took priority, according to Maguire.

“That relationship to the [external] spaces on the site was really key to the layout of the building,” she said. “As a result, we’ve got these two wings and a link, which does make the form factor higher, and therefore there’s a point in time where you can keep putting more and more insulation in but there’s a balance [to be struck]. And that’s where we used PHPP – to start to identify where that balance is, and where you can still get good performance.”

The wall insulation in Beechtrees is far from skimpy, with 240 mm of Steico Flex wood fibre insulation fitted between the timber frame, with a further 100 mm of Steico Special Dry wood fibre boards wrapping the frame externally, delivering a U-value of 0.127. Nonetheless the design allows for more: an extra layer of insulation could be installed very easily by simply removing the timber cladding at some point later, giving this dwelling a highly satisfying degree of cheap and easy future-proofing.

Besides the lower energy targets, the key difference between the AECB and the pas-

sive house standard is around certification. In a nutshell, certification for a passive house can only be awarded by an independent certifier, while the AECB relies on self-certification by the designer or consultant.

According to the AECB website: “The AECB self-certification process is designed to make explicit the project’s claim to be a low energy design and to provide the consumer with a degree of protection under trading standards – without the AECB having to get involved in quality control

Tony and Zoe were adamant the house shouldn’t be too big for their needs or have any wasted space, and no clutter. “We have no space that’s underutilised, and no junk”.

and legal matters.

“This approach puts the responsibility for performance claims clearly with the person signing the certificate and a duty of care on the client to ensure that the consultant is competent and suitably insured.”

Kirsty Maguire herself is a big advocate

of passive house certification, and recently undertook passive house certifier training, becoming the only Scottish-based consultant to have this. Having designed several certified passive house projects over the last decade, Kirsty says with Beechtrees she made sure the quality assurance process was

the same, along with the details and the general approach to the project.

Which was surely music to the ears of Tony and Zoe, who were introduced to the passive house concept by their daughter, and were inspired enough to make enquiries that quickly led them to Maguire’s door and the start of an in-depth but by all accounts very amicable and free-flowing discussion about what they wanted. Their brief was for an environmentally sustainable and warm home that maximised the access to the outdoor space around the site so that they could enjoy the garden and walk their dogs and entertain family, and also recycle as many of its elements as possible.

“There were quite a lot of things we put on the brief,” says Zoe, “such as being able to have the doors open when we’re cooking, and positioning the house so we could make the most of the private bit of garden… we needed a mud room for the dogs – a place where three filthy Labradors can go and shake.”

They were also adamant that the house shouldn’t be too big for their needs or have any wasted space. “I think we were very keen to have no clutter. We were ruthless before we moved in about throwing things out that hadn’t been used. And thankfully we have no space that’s underutilised, but neither do we have any junk.”

Kirsty’s experience and a highly communicative approach to working with Zoe and Tony, allied with the enthusiasm and commitment of a local contractor undertaking one of his first passive house-in-

North east elevation

North west elevation

formed projects, meant that Beechtrees succeeded – even exceeded – expectations in terms of meeting their quite specific demands.

“Kirsty is so kind of efficient and pedantic, in the nicest possible way, about detail that she and her assistant really pushed us hard to make decisions before it even got out of the ground, such as things about light switches, outside lights, positioning of inside lights, colour of the kitchen, colour of the tiles,” said Zoe, who even admits to

getting a “wee bit stressy” about it as the process went on, “but oh my goodness, did we realise the value of that during the build”.

They’re also full of praise for Kirsty’s choice of contractor, David Broatch of Broatch Construction, a firm based just 20 miles away, even though he had limited previous experience of working on passive houses.

“They had never built a house like this before, and... Kirsty must have had some intuition about them,” said Tony, who was sceptical that they would take on the job with the limited budget they had, “but she was right. They really wanted to get it right. And they concentrated so hard on doing that.”

It was clearly a transformative experience for Broatch, because he has gone on to completely change his business focus as a result of this project, heading into passive house in a big way. The firm has recently completed building a home for the daughter of wellknown passive house architect Jonathan Hines, managing director of Architype, on the strength of Kirsty’s recommendation.

Adding to the highly positive build experience was the efficient sourcing of ma-

terials just before the chaos of the Covid pandemic, so that the only supply issue was bathroom tiles, which Tony and Zoe sourced elsewhere in order to keep to the schedule. Only the windows and doors were a little late, but this added just three weeks to the projected 16-week build time.

The choice of timber frame construction was a simple decision given timber frame’s dominant position north of the border, so expertise and skills were easy to find. “We’ve got obviously great joiners across everywhere who are familiar with it so it’s a sort of standard way of doing things up here for buildings at this scale.

Kirsty also describes Beechtrees as a bit

1 The house is named after the mature deciduous trees from the site; 2 Isoquick insulated foundation system and timber frame; 3 400 mm Steico Flex wood fibre insulation in the bedroom wing; 4 airtightness taping at window; 5 heat recovery ventilation ducts in void inside airtight layer; 6 threshold detail; 7 & 8 salvaged tiles; 9 Greencoat PLX standing seam roofing system.

We needed a mud room for the dogs –a place where three filthy Labradors can go and shake.

Drone photography: Ali Yassine

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of a dream project. “We had great clients, really fantastic to work with, really good at making decisions, and great ideas. We also had really good colleagues in the design team so we could work together quickly in a straightforward way.

“And then working with the contractor was fantastic,” she added. “They would come to us with the potential of how to make things even better than we had so we can learn from them as well and keep that discussion flowing. The work that they did was in accordance with drawings and beautifully done, and it was on time, on budget during Covid. I’m not quite sure what more we could have asked for really.”

It’s rare that a client is less than delighted with any project worthy of being featured in this magazine, but Tony and Zoe exude

a particular pride in what their two-bed home represents in terms of its modesty, efficiency, sustainability and, above all, a dwelling that’s tailor-made for them right down to the last detail and with no attic or any kind of wasted space. And of course, a very comfortable home.

Having lived all their lives in old houses with nooks and crannies, big sandstone walls that Tony describes as “just big sponges full of water”, they now live in an “almost perfectly controlled environment”.

“We’ve got the air circulation system in the heat exchanger, which brings in fresh air, collects the warmth from the house and pumps out the stale air. We’ve got fresh air to breathe; even if we don’t open a single door or window, we’ve got lovely fresh air, of the right temperature.”

SELECTED PROJECT DETAILS

Client: Zoe Roberts and Tony Francis

Architect: Kirsty Maguire Architect Ltd

M&E engineer: Luths Services

Civil/structural engineer: Narro Associates

Energy consultant: Kirsty Maguire

Architect Ltd

Main contractor: Broatch Construction

Quantity surveyors: McGowan Miller

Construction Consultants

Mechanical contractor: Paul Heat Recovery Scotland

Airtightness tester/consultant: Thermal Image UK

Wood fibre insulation: Steico, via Ecomerchant

Insulated foundations: Isoquick

Airtightness products: Ecological Building Systems

Windows and doors: Green Building Store

Flooring: Howdens

Roofing: Greencoat PLX

Infrared panels: Trotec

Hot water heat pump: Vaillant

Mechanical ventilation: Paul Heat Recovery Scotland

Heating controls: Heatmiser

They’re particularly pleased with the work of a local furniture maker, Philip Wilson, who cut down the beech tree that obviously inspired the house’s nomenclature and then created beautifully rustic shelves and windowsills with the wood, all finished with a very distinctive blue resin. “It’s terribly, terribly original and just so beautiful to look at.”

Viewed purely from an energy performance perspective, Beechtrees could have pushed the envelope a little more with still more insulation or a more compact form. But energy performance and thermal comfort are not the only requirements to consider, and this thoughtful, skilfully designed house makes a strong case for allowing a little leeway, and is tailored to meet the needs of its owners throughout their later years.

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Building type: Single-storey detached property.

TFA 107 m2

Site type & location: Site in a hamlet on the outskirts of Thornhill village, Dumfries and Galloway

Completion date: February 2021

Budget: £261,000

Number of occupants: 2 adults and 3 dogs

Energy performance standard: AECB

CarbonLite Building Standard

Space heating demand (PHPP): 32 kWh/m2/Yr

Heat load (PHPP): 17 W/m2/yr

Primary energy renewable (PHPP): 87 kWh/m2/yr

Heat loss form factor: 5.5

Overheating (PHPP): 2 per cent of year above 25 C

Energy performance certificate (EPC): B82

Airtightness: 0.42 ACH @50pa

Embodied carbon: Not calculated. Similar to Dundee passive house published in issue 38 of Passive House Plus, although without the PV array.

Energy costs: Total metered electricity usage in first year for all uses of 6,087 kWh. Assuming the current average electricity energy guarantee for Great Britain of 34p per kWh of electricity, with a daily standing charge of 46p, the total household energy bill for all uses would be £2,237/yr. As metered data wasn’t available on space heating, two options were available for deducing heating use: the PHPP-calculated space heating demand of 32 kWh/m2/yr multiplied by the building’s treated floor area, which would translate to 3,424 kWh/yr for space heating alone – a figure that is likely too high, given the measured whole building total of 6,087 also includes hot water, fans, lighting and all unregulated loads (i.e. plug loads). Therefore, Ofgem UK average electricity use for a two or three-person home of 2,900

kWh/yr (for homes with gas heating) was instead deducted from the measured total, leaving an estimated total for heating and hot water of 3,187 kWh. This comes to a total of £90 per month for space heating and hot water.

Thermal bridging: Not modelled due to costs, so punitively high values were used in modelling to be conservative. Key thermal bridging mitigation measures included an insulated slab with edge detailing, wood fibre insulation layer external to the timber framed walls and roof, windows overclad with insulation on the frame, and rainscreen cladding meaning no blockwork or ties. Thermal bridges through fabric were avoided through design.

Ground floor: 200 mm reinforced concrete slab; 250 mm Isoquick insulated foundation system; Visqueen CPT DPC (jointed to DPM and lapped up over sides of 2-layer 100 mm Isoquick insulation upstand at perimeter); 50 mm screed; Howden’s engineered oak flooring. U-value: 0.095

Walls: 12.5 mm plasterboard; 50 mm uninsulated service void; Pro Clima Intello Plus airtight membrane; 9 mm OSB racking board; 240 mm timber frame fully filled with Steico Flex wood fibre insulation (140 mm + 100 mm); 100 mm Steico Special Dry wood fibre board; 50 mm vented cavity; locally sourced larch timber cladding on battens and counter battens.

U-value: 0.127

Living wing roof: Pitched roof cathedral ceiling featuring 12.5 mm plasterboard; 50 mm uninsulated service void; Pro Clima Intello Plus airtight membrane; 9 mm OSB; 300 mm I-joist rafters fully filled with Steico Flex wood fibre insulation; 100 mm Steico Special Dry wood fibre board; 50 mm vented cavity; 23 mm softwood sarking board; Isomat Pro membrane; Greencoat PLX standing seam roofing system. U-value: 0.110

Bedroom wing: Trussed roof featuring 12.5 mm

plasterboard ceiling; 100 mm service void to allow for MVHR ductwork; Pro Clima Intello Plus airtight membrane; 9 mm OSB; 400 mm Steico Flex wood fibre insulation (4 x 100 mm batts, laid perpendicularly) between trusses; with ventilated cold roof above. Pro Clima Quatro membrane to lap between trusses and over 300 mm of Steico Special Dry wood fibre board where wall extends into roof space; 100 mm Steico Special Dry wood fibre board. Roof trusses on pitch; 23 mm softwood sarking board; Isomat Pro membrane; Greencoat PLX standing seam roofing system. U value: 0.097

Flat roof (above entrance hallway and utility): Warm roof featuring 12.5 mm plasterboard; 200 mm service void; Pro Clima Intello Plus airtight membrane; 9 mm OSB; 175 mm timber rafters; 18 mm plywood deck; Visqueen vapour barrier; 200 mm PIR insulation; 18 mm plywood deck; and Sika Trocal Type S membrane, with waterproofing lapping up to the wood fibre in the adjacent wing roof sections. U-value: 0.117

Windows & external doors: Green Building Store Performance range timber windows and doors with uninsulated frames. Class 4 airtightness ratings, and FSC certified pine. Uw-value: 0.85

Heating system: Trotec infrared heating panels, with a Vaillant Arostor 200 domestic hot water heat pump for hot water only.

Ventilation: Zehnder ComfoAir 350 heat recovery ventilation system. Passive House Institute certified efficiency at 84 per cent.

Water conservation: Water butts for rainwater harvesting from roof for garden. Low flow rate taps, WC and showers.

Sustainable materials: Timber frame, wood fibre insulation, reused/recycled paving slabs, beech from tree on site used in joinery finishes from local craftsman, rebuilt drystone wall in the garden.

IN

BRIEF

House type: 262 m2 barn conversion

Method: Cellulose-insulated timber frame, heat pump

Location: Somerset

Standard: Certified passive house classic

Heating cost: £28/month*

* Estimated space heating demand, based on Ofgem’s energy price guarantee for October 2022. See ‘In detail’ panel for more information. £28 per month

MILITARY PRECISION

WEST COUNTRY BARN CONVERSION BRINGS LOW CARBON COMFORT FOR ARMY FAMILY

Designing a building to the passive house standard for the first time is one thing. But trying to do so when the client is a soldier, the design must accommodate the frame of a barn, and you’re straining to get it built precisely on schedule, during a pandemic, is quite another.

By David W Smith

The trickiest challenge was building a roof inside an existing building. “We were worried about having enough space for the drills, but the builders said: ‘that’s fine. We can crawl into the gaps.’”

With a husband in the army, for years Amelia Taylor lived a peripatetic life, often housed in cramped, draughty military accommodation that could be a dispiriting experience. During this time, she and husband Mike dreamed of owning their own spacious, comfortable home. Now, living in her “slice of paradise,” in the couple’s certified passive house barn conversion on the family farm in Somerset, Amelia reflects on the contrast

with army digs.

“We moved around a lot in the army and, although we had one or two nice places, a lot were dreadful. We had pink carpets and terracotta tiles, and banging pipes. At times it was cold and draughty,” she says. “What I dreamed of was living in a house with lovely clean spaces. After sleeping in army digs, I wanted an en suite bedroom that looked like it was in a hotel, and we needed space for our two daughters, now nine and eleven, as the family grew.”

One of Amelia’s main stipulations for the 262 m2 house was constant warmth, and in that regard, the house delivers in spades. “It’s the dream,” she says. “You get out of bed, you don’t have cold feet. There’s no cold spots. You don’t have to worry about layering up. I always wanted a house you could pad around in and feel warm without putting your shoes on. When I go into someone’s house and it’s cold it’s my worst nightmare.”

Living up to its passive house classic certification, the home hasn’t required heating even on the coldest days in the West Country. “It’s incredible. Even when the temperature fell to -3 C around Christmas, we didn’t even use the heat pump as it was still 19 C in the house, not much cooler than the usual 21 C,” she says. “We’d planned to install underfloor heating, but the architect talked us out of it as it would have been far too hot.”

In summer, when the temperature rose to record highs, Mike was too hot at night. But the couple found that opening two windows, at either side of the house, solved the issue. There is also the option during the day to open sliding doors on both sides of the open-plan living area, and the architect specified a Zehnder heat recovery ventilation system, on the basis that a cooling module can be added at a later date if necessary.

The idea of converting the large cattle barn came from Amelia’s father six years ago. While walking around the farm with his daughter, he pointed at the barn and asked her if she felt it would make a lovely house. Amelia had grown up on the farm and had a sentimental attachment to it. The couple, who were in army headquarters 20 minutes’ drive away in Bristol, began to envisage it emptied of agricultural equipment and remade into a beautiful home.

Project finance was secured via Ecology Building Society, whose C-Change mortgage offered the couple a 1.5 per cent discount on the lender’s standard variable rate for building to the passive house standard. “Ecology were brilliant,” says Amelia. “The passive house discount made all the difference when we compared to all the other lenders who didn’t seem to give two hoots about passive house.”

Sadly, during the construction of their

house, Amelia’s father was diagnosed with Alzheimer’s and she says it is a “godsend” to be able to live on the site. She cooks him three meals a day and can check up on him regularly. The farm business, meanwhile, has been diversified and the family no longer takes care of animals. Amelia manages the rental of residential properties, as well as land to other farmers to graze sheep and cattle.

Planning refusal

But in 2018, when the couple’s application for a Class Q Permitted Development was refused by North Somerset Council, their settled home life seemed a distant dream. It took a two-year battle with several twists and turns and three applications, to win planning permission, which came, finally, in February 2020. “The main issue was it was a working farm and they had worries about health and safety. They also had problems with the impact of the noise and smells from the animals and the noise of the machinery. We had to have a noise survey done and then enclose the area with a wall. Some of it I found a bit ridiculous,” she says.

“Other objections were around an archaic document that said the barns could never be converted into residential properties. We had a brilliant planning consultant who fought every point methodically and we got there in the end. We earned planning a week before my 40th birthday and had a fantastic meeting on site on my birthday, when we

were introduced to Claire Humphreys and Geoff Smith, from the newly created Bristol company Shu Architects, who designed it for us.”

Mike, who was passionate about keeping bills down and future-proofing, wanted to build a passive house from the start and the couple visited the National Self Build and Renovation Centre, in Swindon, to find out more. The planning consultant introduced them to Shu Architects which had recently been founded, offering passive house design among its architectural services – Shu co-owner Geoff Smith had just completed his certified passive house designer course in London. As it was his first passive house, he waived the fee for the passive house elements and used the project as a proving ground.

“I was fortunate on my first one to have friendly and pragmatic clients. Mike was clear from the start that, even when we were having a value engineering exercise, nothing could affect the passive house element,” Geoff said. “Amelia was on site every day, but she didn’t suggest any crazy design changes, which happens with a lot of clients.”

As Shu Architects hadn’t worked on a passive house project before – let alone a passive house barn conversion – Geoff sought specialist assistance, tapping into two formidable experts: Beth Williams from sustainable structural engineers Build Collective to assist with passive house design, with Greengauge providing building

services design and building physics support. “As it was my first one I wanted that support as a lot of the numbers are highly complex,” he said.

Part of the deal for planning permission was to demolish the most rickety of the farm’s three barns, as well as move another barn opposite to the family house and put a new roof on it. Elements of the demolished barn, such as the cladding and wall panels, were recycled and used again in the new barn.

The couple had clear ideas about what they wanted. Mike insisted on a large gym, which Geoff says is “as well-equipped as a professional one”. Both required home studies. Mike is still in the army, but Amelia uses

It’s incredible. Even when the temperature fell to -3 C around Christmas, we didn’t use the heat pump as it was still 19 C in the house.

Photos: Brett Charles Photography | Construction photos: Shu Architects/Make

1 The original barn exterior; 2 and the original interior; 3 east elevation upstand; 4 west elevation; 5 south elevation; 6 triple glazed sliding door from Green Building Store; 7 wall battens and Pavatherm insulation; 8 Medite Propassiv OSB panels and taped interior; 9 liquid membrane was used for creating airtightness seals; 10 pipe insulation; 11 attenuator for noise reduction through the ductwork; 12 airtightness taping at window.

her office for a fashion business. The couple also wanted the three family bedrooms (there are five bedrooms in total) to have en suite bathrooms and there was to be a large open-plan living space. Meanwhile, a snug was designed for the girls as part of an “inflation plan” as they got older and more independent.

The sheer length of the 27.7 m long building made it hard to get enough light into the corridor. But Geoff “borrowed” some light by placing glazed panels above the doors of Mike’s study and the snug. The living spaces were all open to the ceilings and there were windows providing views to the west for the living spaces and to the north for the principal bedrooms. The length of the building also necessitated installing two water cylinders to avoid waiting times for a hot shower. Greengauge used the AECB’s Water Standard to calculate the hot water lag times for all the pipework.

The trickiest challenge was building a roof inside an existing building, although it turned out to be more straightforward than Geoff initially feared. “It was pretty funny as we modified the designs to allow the builders to access the rafters more easily. We were worried about having enough space for the drills, and so on. But the guys who were building it ended up saying ‘that’s fine. We can crawl into the gaps’. So, that was the difference between an architect’s perspective and a contractor’s!”

There were a few jitters at the outset after the first Covid-19 pan-

Section view showing the box within a box approach used to create a thermal envelope

demic lockdown was announced in March 2020, just a couple of weeks after Geoff was introduced to the couple. But the build went ahead with pre-design meetings reverting to Zoom. The contractor, MAKE, started work on the house in November 2020 and completed the build on 5 September, 2021, the precise day they had predicted. “It was in my diary and I told friends I couldn’t do anything that weekend. They laughed and said ‘these things always run over. You’ll never be moving in on that day’. But they did it!” said Amelia.

Geoff says the contractors were meticulous in everything they did. “The pressure is always on them to achieve airtightness and they absolutely did the best they could. They ended up buying pots of Passive Purple and, when they weren’t busy with other things, applied a liquid membrane to every nail hole on the boards going into I-Joists, in addition to all the taping done on the board. “They also painted the junction where the board comes down onto the slab, and they put a flexible silicone sealant underneath the battens when they pushed them on, and they also painted them,” he said.

The careful workmanship brought the desired outcomes. A first airtightness test produced a reading of 0.2. A second one came out with 0.3, but only because a sliding door broke just minutes before the test and had to be taped up. Finally, the third test was 0.135. “Once you’ve done the training and worked on a passive house design, and you go back and look at building regulations, you wonder how you ever worked differently before,” said Geoff.

SELECTED PROJECT DETAILS

Architect/passive house design: Shu Architects

M&E engineer/energy consultant/ building physics support: Greengauge

Civil/structural engineer: Build Collective

Project management/quantity

surveyor: Ross Management Services

Main contractor: MAKE

Cellulose insulation: PYC

Wood fibre insulation: Soprema

Airtightness products: Ecological Building Systems

Airtight OSB: Medite Smartply

Windows and doors: Green Building Store

Heat pump: Vaillant

Radiators: Henrad

Mechanical ventilation supplier: Zehnder

Mortgage: Ecology Building Society

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IN DETAIL

Building type: 262 m2 (TFA) detached timber frame passive house within an existing steel framed agricultural barn.

Location: Tickenham, North Somerset

Budget: Confidential

Completion date: September 2021

Space heating demand (PHPP): 13 kWh/m2/yr

Heat load (PHPP): 7 W/m2

Heat loss form factor (PHPP): 3.44

Overheating (PHPP): 1 per cent of year above 25 C

Number of occupants: 4

Primary energy demand (PHPP): 29 kWh/m2/yr

Energy standard: Certified passive house classic

Energy performance certificate (EPC): B 88

Measured energy consumption: Unavailable

Heating costs: Calculated space heating cost of £27.97/month. This is based on the building’s calculated space heating demand of 13 kWh/ m2/yr, 262 m2 treated floor area, and the UK

average electricity price based on the Energy Price Guarantee from 1 October 2022 of 34p per kWh, with an assumed Seasonal Coefficient of Performance (SCOP) of 3.45 –the worst available result at the time of writing for this model of heat pump – taken from heatpumpmonitor.org.

Airtightness (at 50 Pascals): 0.1 air changes per hour

Ground floor: 200 mm reinforced concrete slab on 250 mm Kingspan GG300 XPS insulation.

U-value: 0.139 W/m2K

Walls: British Cedar cladding, counter battens and battens, 60 mm Pavatherm insulation, 360 mm timber I-joists with blown Warmcel insulation between, 12 mm Medite Propassiv OSB, 25 mm battened service void and 12.5 mm skimmed plasterboard. U-value: 0.091 W/m2K

Roof: Existing 100 mm insulated steel roof, ventilated void, breather membrane, 12 mm Panelvent racking board, 400 mm I-joists with blown Warmcel insulation between 12 mm

Medite Propassiv OSB, 25 mm battened service void and 12.5 mm skimmed plasterboard.

U-value: 0.092 W/m2K

Windows & doors: New triple glazed windows, entrance door and sliding doors. Green Building Store Ultra GBS98 timber inward opening windows, Argon-filled. Overall U-value of 0.71 W/m2K

Heating system: Vaillant AroTherm 12 kW split air source heat pump – with low global warming potential (GWP) R290 refrigerant – with Henrad low temperature radiators throughout.

Ventilation: Zehnder ComfoAir Q600 heat recovery ventilation system — Passive House Institute certified to have a heat recovery rate of 87 per cent.

Water: We assessed the dead leg volumes and times against the AECB Water Standard. This was reflected in the decision to use two HW cylinders (in the plant room and adjacent to the guest bedrooms), as the house is single-storey, and it is very long in plan.

IN BRIEF

House type: Deep retrofit to 211 m2 1960s detached house

Method: External insulation, air source heat pump, PV array

Location: London

Standard: Enerphit certified

Heating cost: £43 / month*

* Estimated space heating cost – ignoring contribution from PV array – based on Ofgem’s energy price guarantee for October 2022. See In detail panel for more information.

£43 per month

MODERN LOVE

1960S MODERNIST GEM GETS ENERPHIT TREATMENT

Where does the balance lie between conservation of buildings, energy and nature? One deep retrofit to a London modernist house may point the way ahead, bringing light, form and avant garde energy performance to old ideas about contemporary living.

By Jason Walsh

No-one could ever accuse modernist architects of lacking vision. Indeed, from Le Corbusier to Oscar Niemeyer, to Erno Goldfinger, the more typical complaint is of a surplus of vision. Nevertheless, despite modernism’s controversial place in the history of our built heritage due to mass housing schemes loved and loathed in equal measure, there is a certain something about one-off modernist houses. While we may not really want to live in a machine, the form-follows-function idea (or pretence of it, at any rate) left us with houses that are not only striking but made interesting use of light and space.

What the architects of the post-war reconstruction did lack, however, was an understanding of how energy use would become paramount in housing design.

One recent refurbishment project in southwest London, however, has seized the opportunity to marry the modern with the contemporary, creating a certified Enerphit home fit for how we live today.

Designed by Michael Blackstock in the 1960s and left untouched for at least 40 years, the three-storey, three-bedroom house was not unknown, having received notices in the press when it was last on the market in 2015. What it also was not, however, was a good performer in terms of energy.

Owner Aline Knowles, herself an architect by training, approached Richard Dudzicki, founder of RDA architecture, to transform the house from a damp, leaky and dated

time capsule into the light-filled, calm retreat it had always promised to be. Central to the plan was bringing it up to passive house standard.

Crucially, exterior insulation was fitted, glazing replaced, and an integrated solar roof added. In addition, rainwater harvesting was added and the interior was completely refurbished, not only to improve the aesthetics but also to allow for the installation of mechanical heat recovery ventilation.

It soon transpired that the house was in need of extensive repair, including to the building fabric, which suffered from air leakage and dampness. Dudzicki said that one difficulty on starting the work was the fact it is a reinforced concrete building, so until the build work was underway it was not possible to know where the pre-stressed areas would be and where to create or leave existing openings. There would be other surprises, though.

“We soon discovered it was a mixture of block and beam, reinforced concrete, and all sorts. It was almost as if they started as one thing and then ran out of money and had to finish it a different way,” he said.

Phenolic insulation was used externally and lime render was used to ensure the walls were breathable, but one party wall was fitted with a different insulation panel due to a lack of space.

“There is a lot of thermal mass in that building, lots of concrete, so it lent itself to external insulation,” he said.

An existing drive-through garage was added to the building envelope and repurposed into an art studio and main entrance lobby, making the house more usable without interfering with its 1960s aesthetic. That same 1960s aesthetic, however, provided plenty of other challenges.

“We gutted the entire inside. It was an upside-down living house, and all the bedrooms had these strange cubby holes and cupboards. It didn’t fit how the client

wanted to live and work in the house,” Dudzicki said. A treacherous spiral staircase was also replaced.

In-situ underfloor heating was kept, but the heating system was changed to an air source heat pump – Dudzicki specified a Mitsubishi Ecodan Ultraquiet to reduce noise – and the new building services required significant work.

“We installed an air source heat pump and mechanical heat recovery ventilation, which was quite hard. We really had to work out the route early on with the structure engineers but, in the end, we found areas where we could drop the ceiling without affecting the room and that gave us the space to get the ducting in,” he said. But a couple of aspects of the original house design lent themselves to retrofit: the original house featured air-based heating and existing copper underfloor heating pipes. Existing voids designed for the air heating were used to run ductwork, and the copper underfloor heating pipes were chemically cleaned by a professional and reused.

Photovoltaic panels were added, alongside high-performance Tesla batteries for storage. Dudzicki said the batteries are much hyped, and they do work, but are not really the miracle some reports suggest: “Would I put one in [my own home]? Maybe. They’re OK. They integrate really well with Tesla cars, I’m sure,” he said.

The PV panels were another story altogether, and Dudzicki is very happy with them. Rather than being attached to the roof, the panels actually form the roof itself.

“The solar panels are the roof, there are no tiles underneath it. That was quite novel. The hidden gutter around the side is where the water runs off,” he said. This water is then harvested and used to fill a pond and water the garden.

Passive solar issues were also considered, with solar shading added to windows as well as room for blinds: “We also used planting on the balcony as a solar screen,” he said.

Roof lights on the top floor ceiling, one of the building’s most striking original features, also posed a challenge, as well as demon-

Photos: Timothy Soar

If the architect in 1966 had understood energy the way we do today I am sure he’d have done very similar things.

external insulation.

strating the limits of the modernist imagination in the 1960s.

“The roof is mono-pitched with southerly, south easterly sky lights and they were single glazed, which gave a real issue with heat loss. It was freezing,” he said.

Removing them would have taken away a crucial aspect of the building, however, so Dudzicki’s answer was to make them slightly smaller and triple glaze them. Similarly, the wood ceiling was replaced with one that matches the original vision for the house, as were the architraves, doors and kitchen, all faithful to the original design.

For Dudzicki, the house is a kind of vindication: it proved that modern houses, through extensive retrofitting, can be made to meet the needs of twenty-first century living.

“We tried to keep the modern feel. If the architect in 1966 had understood energy the way we do today I am sure he’d have done very similar things,” he said. Indeed, Dudzicki comes from a family of architects, with his father working on similar housing after the Second World War.

“What we tried to do was really look at the design and try to make it function from a contemporary point of view. What I wanted to do was not have a hippy-trippy thing. Sustainability had always been seen a bit like that, so I wanted to prove that it could be done differently,” he said.

With climate now firmly on the political agenda, not to mention a housing shortage, Dudzicki, who himself lives in an Enerphit house, says that, given the right care and attention, projects like the Blackstock house could be scaled up to confront these two issues.

“You do need a good six month period at the start with a retrofit and that’s very difficult in the current market, and with the housing stock in London there are so many conservation areas [but] most of the brutalist, modernist buildings which people don’t want to conserve could be retrofitted. The fact is, they tend to lend themselves to things like external insulation,” he said.

Most of the brutalist, modernist buildings which people don’t want to conserve could be retrofitted. They lend themselves to

Ground Floor Plan

1. Side alley

2. Utility room 3. Storage 4. Bed 1

5. Hallway 6. Plant room

7. Ensuite 8. Lobby 9. Studio

First Floor Plan

Second Floor Plan

1. Bed

2. Ensuite

3. Bed 4

4. Hallway

5. Master bedroom 6. Bathroom

7. Balcony 8. Living / dining room 9. Kitchen

SELECTED PROJECT DETAILS

Client: Aline Knowles

Architect, project management, landscape design: RDA Architects

Civil / structural engineer: Michael Baigent Orla Kelly Ltd

Energy consultant: Ecospheric

Main contractor: PJS Building & Maintenance Ltd

Quantity surveyors: Saville Brown

Airtightness tester/consultant: Air Testing Ltd

Lime render and cladding: Mike Wye & Associates Ltd

Thermal breaks: Farrat

Airtightness products: Siga

Windows, doors and rooflights: SNT

Screeds: Ecomerchant

Fit out and furniture:

Scandinavian Trade Ltd

Flooring: Senso

Rainwater harvesting/drainage/paving: Rain Water Harvesting Ltd

Insurance: Self Build Zone

Heat pump: Mitsubishi

Hot water tank: Mixergy

Mechanical ventilation: Zehnder

Photovoltaic roof: GB Solar

Lighting: MSLD Lighting Design

Lighting controls: Corston

Water conserving fittings: Crosswater

Sanitaryware: Kaldewei

SNT Europe Ltd.

Lightbox, G24, 111 Power Road, Chiswick, London, W4 5PY, United Kingdom

For inquiries please email fc@snt-europe.com

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Architect’s statement

Our client Aline (an architect by training but now a DJ) wanted this 1960s modernist house designed by Michael Blackstock to be restored, combining the original design aesthetic with a contemporary approach. The three-storey property was designed in the ‘upside-down’ style common in the 1960s, with an open plan living space and terrace sitting above cramped bedrooms and bathrooms on the first floor, and a ground floor parking and utility area.

This is not a straightforward house or design. The house was in need of extensive repair works (including building fabric itself, addressing air leakages and dampness), Instead of demolishing a historic award-winning project, we breathed new life into the building using modern technology to extend its lifespan by another 100 years.

The layout was addressed to take into consideration a more modern way of living, simplifying the live-work aesthetic that was

needed. RDA focused on improving the circulation by separating private and public spaces, and connecting these spaces with the garden. Attention was given to recreating bespoke fittings to mimic the pre-existing wooden joinery.

The passive house standard requires highly efficient insulation, and new windows and doors have also been fitted to improve airtightness, reducing heat loss, providing a high level of comfort throughout the house. This is a pioneering retrofit approach, while aligning with the RIBA 2030 Climate challenge, being a precedence to bringing the housing sector towards zero carbon emissions by 2050.

This project with its Enerphit value, corresponds to UN Sustainable development goals number 7 (Affordable and Clean energy),11 (Sustainable Cities and Communities) and 13 (Climate Action). Within this framework, it is an encouraging example

WANT TO KNOW MORE?

The digital version of this magazine includes access to exclusive galleries of architectural drawings.

The digital magazine is available to subscribers on passivehouseplus.ie & passivehouseplus.co.uk

to its neighbourhood and within the larger context of the UK, for more sustainable and energy efficient buildings. In addition, it is almost like a living lab as it is being monitored constantly to be adjusted to the best performance it can achieve. Similarly, the data gathered during its monitoring process, can actually provide insight for the broader design community, excelling the design decisions towards more sustainable features.

This house consumes 88 per cent less energy than an average UK home. The total PV panel system size is 7.8 kW, corresponding to 77 per cent of all the energy needed.

According to British Gas data, while the average energy bill of a typical UK house costs £2,500, the energy bill for this house is expected to be as low as £177 annually thanks to its design.

This house provides a very important example of implementing successful energy management.

Cuts

Lower

Removes

Prevents condensation

Resistant to aging

No harmful toxins or solvents

Safe and quick to apply

IN DETAIL

Building type: Deep retrofit and renovation to 211 m2 modernist house designed by Michael Blackstock in 1960

Site type & location: Urban site, New Park Rd, Lambeth, London

Budget: £498,000 complete construction cost, including contractor overheads and profits and any contractor-team design fees, excluding VAT, site purchase and design team fees.

Completion date: May 2022

Passive house certification: Enerphit Plus certification

Space heating demand (PHPP)

Before: Approx 168 kWh/m2/yr

After: 26 kWh/m2/yr

Heat load (PHPP)

Before: Not available

After: 14 W/m2

Primary energy non-renewable (PHPP)

Before: Not available

After: 120 kWh/m2/yr

Primary energy renewable (PHPP)

Before: Not available

After: 74 kWh/m2/yr

Form factor (PHPP): 3.06

Overheating (PHPP): 6 per cent of year

above 25 C

Number of occupants: Two adults and a dog

Embodied carbon:

Maintained the already existing concrete substructure and superstructure, with natural materials used where possible. The roof was redesigned to have PV solar panels replacing tiles, excess energy generated is stored in a Tesla power wall. Finally, rainwater is collected by the roof and stored in underground tanks for external use.

PHribbon whole life carbon methodology was used. Both upfront carbon RICS modules A1-A3 and RICS whole life carbon modules A1-A5, B1-B5, C1-C4 including sequestration are calculated and visualised in graphics. In order to compare against RIBA 2030 embodied carbon level, the latter is taken into account. Cradle-to-grave assessment boundary is applied. Building life is assumed as 60 years.

Whole building embodied carbon score of 562

KgCO₂eq/m² using PHribbon.

Measured energy consumption

Before: 214 kWh/m2/yr

After: 25 kWh/m2/yr

Energy bills

Before: Not useful to compare, given that pre retrofit energy use was pre energy crisis.

After: Calculated at £43 per month on space heating. This is based on the building’s calculated space heating demand of 26 kWh/m2/yr, 211 m2 treated floor area and the UK average electricity price based on the Energy Price Guarantee from 1 October 2022 of 34p per kWh, and the measured mean seasonal COP result of 3.6 for this model of heat pump taken from Heatpumpmonitor.org

Thermal bridging

Therm calculations for key junctions – including the southeast side wall where thinner external insulation was required due to the proximity of a neighbouring property, meaning a greater thickness of internal insulation was required. Farrat plates used at steel penetrations. Windows and doors bracketed into external insulation layer.

Airtightness

Before: N/A

After: 0.82 air changes per hour (m³/hr m² at 50pa)

Ground floor

Before: Uninsulated concrete floor. U-value: 1.6 W/m²K

After: (top to bottom) Sesno resin, Fermacell board airtight layer, phenolic insulation, rubber crumb mat, DPM, reinforced concrete. U-value: 0.13 W/m²K

Walls

Before: Approx 215 mm double layered brick wall. U-value: 0.7 W/m²K

After: (inside to out) Regency lime plaster airtight layer, eco cork lime plaster, phenolic insulation, brick slips to match existing. U-value: 0.2 W/m²K

First floor Walls

After: (inside to out) Plaster skim, phenolic insulation, lime plaster, double layered brick wall, Thermaline render. U-value: 0.139 W/m²K

Roof

Before: Leaking asphalt roof with 100 mm of Rockwool insulation in between joists.

After: Solar roof acting as rainscreen; phenolic insulation, Siga Majrex membrane; phenolic insulated plasterboard; pine cladding. U-value: 0.088 W/m2K

Windows & doors:

Before: Single glazed, timber windows and doors.

New triple glazed windows: Passive house standard requires highly efficient insulation; new windows and doors have also been fitted to improve airtightness – reducing heat loss, providing a high level of comfort throughout the house. Overall U-value: 0.84 W/m2K

In order to achieve high performance, airtightness sealing and tapes are used across all interior envelope and junctions, and as required by Enerphit principles.

Heating system:

Before: 50-year-old oil boiler & radiators throughout entire building with some underfloor heating that was not working.

After: Mitsubishi Ecodan Ultraquiet air source heat pump

Ventilation:

Before: No ventilation system. Reliant on infiltration, opening of windows for air changes. The living room on the top floor was prone to overheating.

After: A Zehnder MVHR system is used to ensure fresh air quality together with Passive House Institute certified heat recovery efficiency of 88 per cent.

Water: Mixergy water tank technology directly connected to PV system. There is a rainwater harvesting system which collects water from the roof. The water is used for the hot tub and external use.

Electricity: PV Panels of 7.8 kW capacity are used for energy generation, Tesla battery storage is added to system to store the energy, prioritised for domestic hot water heating via immersion and electric car charging, excess electricity exported. Sustainable materials: Pine cladding and plywood from FSC sources, eco cork lime render. Restoration and reuse of old underfloor heating system.

ADAPTATION SENSATION

LANDMARK DUBLIN BUILDING PIONEERS DYNAMIC ADAPTIVE COMFORT APPROACH

Sometimes a building comes along that asks challenging questions. Chris Croly, building services engineering director of BDP, describes one such example – a building designed to tackle the specific energy profile of offices, while trialling an innovative, dynamicallycontrolled approach to adaptive comfort.

IN BRIEF

Building type: Large office block subdivided into two, totalling 39,000 m2 gross internal area

Key method: Adaptive comfort-based approach to cooling, heating and ventilation

Location: Dublin City

Standard: BREEAM Excellent

Energy use: 83 kWh/m2/yr*

* Total delivered energy use, based on the first five months of monitored usage.

83 kWh/m2 per year

The carbon intensity of electricity in Ireland has reduced by 50 per cent over the last 15 years and is on track to achieve an 80 per cent renewable energy content by 2030.

The Electrical Supply Board (ESB) is a semi state group that has contributed to this achievement. They have set a target of being completely carbon neutral by 2040, investing heavily in renewable generation and associated technology such as energy storage.

As an energy company working within this context, the redevelopment of their offices in Dublin’s Fitzwilliam Street presented an opportunity to invest in the advancement of sustainable office development.

The majority of new offices rely on either a LEED or BREEAM environmental certificate to demonstrate their environmental credentials. While these certificates can give the impression of a building that performs well in all environmental aspects, they often mask a monitored energy performance that differs little from offices constructed decades earlier. Modern office design requires a step change in approach to achieve genuine energy savings.

The Fitzwilliam project contains two next generation office buildings, the first of which is used as the ESB’s headquarter offices, and also serves as a research tool. It provides a treasure trove of new techniques and technologies that have been shown (through subsequent monitoring) to dramatically reduce energy usage in offices.

The second building includes many of the same techniques but is optimised for the commercial market. This was an important aspect of the project as the office market

in Dublin invariably offers sealed, air conditioned buildings that struggle to achieve their energy aspirations. There was a need to introduce an alternative precedent and guide the market to low energy solutions.

The commercial office produced offers a new hybrid ventilation strategy that takes advantage of free cooling while offering comfort and air quality levels that exceed that of a typical air conditioned office. The market responded by showing a strong approval of the approach and placed a value on the building that notably exceeded the cost.

Procurement process

A design competition was held to select the project architect and their overall approach to the building. The unusual step was taken of appointing the mechanical/electrical and sustainability consultant (BDP) in advance of the architectural appointment to ensure that sustainability formed a key element of the architectural competition. Grafton Architects were appointed in conjunction with O’Mahony Pike Architects with a scheme that had the potential to embrace hybrid ventilation.

While a design and build contract was used for the shell and core of the buildings, BDP were conscious that the design and build process by its nature rarely prioritises environmental innovation. For the commercial block it was also important that a future fit-out would not dilute the services design envisaged. The solution was to fully design the key fabric elements for both blocks and the core services within the commercial block prior to the design and build competition. PJH were then appointed as

the design and build contractor to complete the shell and core construction.

The ESB offices were then fitted out by Walls Construction with Jones Engineering Group as services sub-contractors, and Aecom were the fit-out architect. BDP were retained as sustainability and mechanical/ electrical consultant, while also assisting with monitoring the design and build contract to ensure consistency of environmental approach at all stages.

The approach allowed BDP to invest in the buildings as a research project and fully develop the new strategies implemented in both buildings.

Passive design

Traditional office design norms such as the use of fully glazed facades were banned, and each element of design was required to reflect the principles of building physics to reduce the building’s demand for heat, cooling and lighting.

LEED and BREEAM certificates often mask a monitored energy performance that differs little from offices constructed decades earlier.

Exterior photos: Alice Clancy / Ros Kavanagh | Interior photos: Donal Murphy

Fitzwilliam Street elevation

James Street East elevation

Hybrid ventilation

Modern offices often have a net cooling load throughout the year and external temperatures in Ireland are almost always lower than the internal temperatures required. This means that the tradition of sealing offices from their cooler external environment and then actively cooling them must end.

It can be tempting to think of a naturally ventilated office as the ultimate low energy solution, but the approach doesn’t allow heat recovery and often struggles to produce a comfortable and healthy environment.

A sealed air conditioned office guarantees precise internal conditions but is energy hungry and often produces a sterile environment that ultimately doesn’t deliver on health and comfort.

The new hybrid ventilation approach combined the best of all systems to achieve an enhanced level of air quality and an energy performance that has proven to be

better than most naturally ventilated offices.

It was not possible to identify a clear precedent for this approach as tradition frowns on the use of opening windows in fully air conditioned buildings. In part due to a concern that the energy used to cool them will be lost through open windows, air conditioned offices are invariably designed as sealed buildings. This is a valid concern where fixed internal set point temperatures are used but the constraint has been overcome by adopting a new approach to adaptive comfort.

The human response to temperature is complex and adaptation occurs naturally in warmer weather. Following several days of warm weather, people become more comfortable at warmer temperatures and even start to feel cold if the internal temperature is held down artificially.

This building pioneers a new control solution that allows the peak comfort temperature to be influenced by external temperatures that have occurred in previous days and weeks, with a higher weighting given to the most recent weather conditions.

As the resulting internal temperature is almost never below the external temperature, staff are free to intuitively open windows to naturally improve both energy usage and comfort. It is hoped that the demonstration of this control method will offer an invaluable example for future reference.

Early monitoring results have demonstrated that the strategy is very effective and has produced a record breaking monitored cooling energy usage below 4.5 kWh/m2/yr. This figure includes the comms room and specialist facility cooling and the cooling

in open plan office areas was close to zero, reaching only 4 W/m2 when external temperatures peaked at 29 C during the summer 2022 heat wave.

The combination of natural and mechanical strategies with a new fan control technique has also reduced fan energy by more than 85 per cent compared with a typical office. Air quality is continuously measured by both CO2 and VOC sensors and excellent air quality has been achieved.

Façade design

The glazing areas have been adjusted by location, considering the yearly simulations of sunlight falling on each window. In particular, glazing on the upper floors, which are more exposed, have a smaller area. South and west-facing glazing is provided with solar control while solar gains are encouraged from the north and east. The key south façades are also provided with vertical external shading that is optimised to block solar gains in the afternoon.

Insulation and infiltration

Opaque elements have a U-value in the order of 0.15. The monitored building heating load is so close to zero that any increase in thermal performance would increase the embodied energy of materials used at a higher rate than the savings produced.

In most sealed offices, the level of air leakage achieved has become so small that it unwittingly increases the energy used by reducing natural cooling. It increases cooling loads more than it reduces heating loads.

During the night in winter, when it is important to prevent heat from escaping there

A naturally ventilated office may seem the ultimate low energy solution, but it doesn’t allow heat recovery and often struggles to produce a comfortable, healthy environment.

is a benefit to having an airtight structure but later in the day, even in very cold weather, offices need to be cooled. Cracking open the high-level motorised windows encourages useful air transfer without causing draughts. This is implemented automatically whenever there is a net cooling load in the building.

Monitored heating energy demand has been less than 7 kWh/m2/yr. and roughly 25 per cent of that energy has been provided by recovering waste heat from cooling processes.

Ventilation

The building is set around a series of planted courtyards with all office areas having access to external spaces, natural light, and ventilation. Because the courtyards are set back from the street, they allow natural ventilation with less traffic noise and improved air quality.

Low level manual openings are provided for staff and motorised openings are provided at high level to reduce draughts and allows warm air out above head height. The automated windows have multiple functions including cracking open in cold weather, opening fully in warm weather, and providing night cooling. The high-level openings can also be manually overridden by staff.

An often-ignored constraint of opening windows is that in warm weather, blinds are pulled over the openings to prevent glare, blocking the free flow of air. Solid window sections were used to prevent this contradiction. The openings are also protected by external shading which takes the form of vertical fins that do not restrict airflow.

Exposed mass

A strip of 1.5 m of exposed mass is used at the perimeter, raising the glazing level and projecting daylight deeper into the plan.

Deeper plan areas are reserved for tea sta-

tions as they have less need for natural ventilation and daylight. In these spaces an open timber grid ceiling is used. This allows the concrete to be thermally visible while still providing the visual benefits of a ceiling. During the day, the concrete absorbs heat and at night it is released and removed by natural cooling.

A 70 per cent GGBS content was used in the foundations and 50 per cent for the structure resulting in a reduction of 7,200 tonnes of CO2 (160 kg/m2).

ACTIVE SYSTEMS

Fresh Air

Office air is traditionally supplied continuously for all staff, irrespective of how many people are in the building, even to empty meeting rooms and canteens. In this case fresh air is only supplied at the rate required and reduces automatically as windows are opened. The air control system includes a number of innovations including the lowering of fan pressures in addition to volume with load. This rarely understood technique produces dramatic savings in fan energy, particularly during low load conditions.

Typically, in office buildings, a constant supply air temperature is used at all times which wastes both heat and cooling energy, and fails to take full advantage of free cooling. A number of innovative new control strategies are under test in the offices including a self-learning strategy which adjusts the level of free cooling provided based on the net loads.

Open breakout spaces are used for informal meetings which limits the use of more closely controlled meeting rooms.

Heating and cooling

The building is a zero local pollution building with no fossil fuel connections, even for cooking. The operational carbon impact of the building will approach zero along with the national grid.

Air source heat pumps are used to generate heating, cooling and recover heat when simultaneous loads occur.

Cooling is provided from several sources:

• 100 per cent of the hot water for showers, hand washing, catering etc., is provided by a heat pump that recovers heat from the cooling system, offering cooling as a by-product.

• Free cooling is provided by a 4.8 km closed loop ground collector.

• Cooling is recovered from any live heating demands in the building.

• A phase change store is used to transfer cooling loads to the night when there is less demand on the electrical grid.

The phase change material used for the energy store is an advanced product which is similar to ice but changes phase at 10 C. This product is not in common use and is under test in this building. It has characteristics that differ from ice which are not widely understood.

In winter an office has a net heating load in the morning and a net cooling load in the afternoon. The phase change material stores the cooling potential from the morning for use as free cooling later in the day.

The fan coils used for heating and cooling only have one coil which reduces fan energy. This is achieved by using an innovative six port valve that switches each coil between heating and cooling mode. This technique reduces capital and running costs, and em-

bodied energy.

A glycol free system is used which reduces chemical consumption but also improves the heat transfer properties of the water used.

Environmental assessment methods

During the design process the ESB hosted a workshop with the IGBC to compare BREEAM, LEED and the German DGNB environmental assessment methods. The purpose was to study the different approaches used but also to incorporate the best concepts from each method. An assessor was invited from each organisation to review the building and offer suggestions that could be incorporated into the design. The three methods were very similar, but the DGNB method was the most flexible of the methods reviewed. The method also encouraged the team to consider how the building could be designed for increased adaptability in the future.

The building was formally assessed under the BREEAM method and achieved an Excellent rating, but priority was given to actual environmental performance rather than the certification result in the few cases where conflicts occurred.

Water

A ground water well is used to provide local water for flushing and irrigation.

Monitoring and reporting

There is limited detailed energy data available for modern offices. The ESB offices are fitted with an extensive metering package and BDP are monitoring and tuning the building’s performance and post occupancy evaluation process.

It is hoped that the insights produced by this building will inspire future offices to achieve a step change in energy performance and in particular, it is hoped that it will bring about an end to the age of the sealed, air conditioned office.

ARCHITECT’S STATEMENT: GRAFTON ARCHITECTS

In 2009 the ESB organised an international design competition to find an architectural team to design a world‐class office building. Grafton Architects & OMP Architects were successful in their entry to create a building that satisfied the needs of the ESB as well as

the citizens of Dublin on this important and historic streetscape.

Located at the centre of the Dublin’s Georgian Mile and between the 18th century grandeur of Merrion and Fitzwilliam Squares, the challenge for Grafton Architects was to find a way to create a modern office building that could comfortably sit amongst the restrained elegance of the sur rounding Georgian context.

To begin this process, we set about analysing the built fabric of the Georgian streetscape including its rhythm of windows and doors, its hierarchy of floors, its gently stepping parapet lines, chimneys and threshold of railings bridge and basement, which bring light down to lower level. These elements form the essence of the Georgian streetscape, they represent the fundamental machinery of Georgian architecture. The proposal works within this vocabulary, this language of building, in a contemporary way, to make a building sensitive to its surroundings and representative of its own time.

The new building continues the Georgian streetscape and parapet height of a four‐storey brick wall to Fitzwilliam Street Lower. This edge is crafted with a load bearing, ma-

sonry brick wall that has been designed and detailed to harmonise with the existing load bearing brickwork of the street.

The façade to Fitzwilliam St is designed to feel familiar and new at the same time. It feels familiar because it relates to the gracious brick walls of the existing street, which is repetitive and cohesive, where each house is slightly different from the next. It feels new because it is similar but not the same, with new elements subtly introduced to accommodate new uses and new ways of building. The materials used have been carefully chosen to be both sympathetic (brick and Wicklow granite) as well as innovative (thermally broken stepped steel windows).

To James’s Street East, a strong and vibrant streetscape is proposed to provide order and clarity of form. Brick gables face James’s Street East and these blocks open and set back to create courtyards, connections, and sunken gardens spaces. These new forms release a lavish landscape proposal to the street and frame vistas through the scheme from the street.

The design is entwined with a sustainable agenda to deliver a healthy and energy efficient design for its occupants, where a high-quality work environment is provided, delivering flexible and adaptable floor plates, naturally ventilated spaces within a building made with high quality robust materials and workmanship that knits into the city fabric and will stand the test of time

Fitzwilliam Street facade

The wall to Fitzwilliam Street is composed of two solid brick walls built in a composite manner. The outer wall is a self-supporting brick wall to the street while the inner wall is a loadbearing brick wall that supports the concrete superstructure. A thermally insulated cavity separates these two constructions. The brick used is a large (240 x 115 x 73 mm) custom made brick from Gillrath brickworks in Germany. This overall construction measures 800 mm in width and rises to approximately 21 metres from the lower lightwell. Both walls are built in Flemish bond with lime bedding and pointing. The use of load bearing masonry with lime bedding allows for a wall free from mastic filled movement joints. Although building joints are provided every 15 linear metres there are no joints required over the 21 m height of the wall.

The design and build process by its nature rarely prioritises environmental innovation.

Plans showing various floors on the building’s 4, 5, 6 and 7 storey sections including (top to bottom) the ground floor, third floor, fifth floor and roof top; and a massing model of the building

indoor air for nearly 40 years. Easy

The loadbearing structure of brick piers stack from level to level, there are no concrete columns or steel frames embedded in the structure. The slab has exposed concrete coffers bearing onto the brick structure and varies in depth from 150 mm to 250 mm. All elements that require structural support, such as the staggered steel frame windows, granite surrounds, copings and gates are all fixed to the inner brickwork and are cantilevered over the external wall allowing for independent movement between the inner and outer parts of the wall. The windows are finished internally with a solid oak liner which splays to allow additional light from the west.

The windows to Fitzwilliam Street are a thermally broken steel window system. A ventilation flap is incorporated at the step in the window section. The window openings in the outer brick wall are lined with a feathered reveal of lime mortar. Masonry flat arches are used to form the window openings in the wall. Larger openings make use of precast concrete elements built into the wall as loadbearing lintols. Leinster granite is used extensively on the Fitzwilliam Street Façade, for the cills, steps, kerbs, parapets, railing base and colonnade linings. The street side wall of the lower lightwell is lined in glazed bricks to reflect daylight into the lower ground level and courtyards.

Courtyard facades

The courtyard facades are constructed from Techrete precast concrete panels and canopies with a grit blast finish. The panels are composed of white cement

concrete with a granite aggregate. There are two different types of grit blast finish, one rougher than the other. In terms of support, the panels at lower levels are stacked whereas on the upper floors they are corbelled off the concrete superstructure. The plan geometry of the panels varies depending on the orientation of the facade, with the south facing facades having deeper fins to assist with solar control The openness of the panels varies from the roof to lower ground floor, with the solid to glass ratio reducing as the building descends, allowing for additional light penetration to the lower levels.

Superstructure

The superstructure of the building - which was the overall winner and building category winner at the 2022 Irish Concrete Society Awards - is an exposed concrete frame with suspended flat slab floors. The use of GGBS was maximised in the project, with 70 per cent GGBS being used in the lower floors and 50 per cent GGBS in the upper floors. A series of concrete Vierendeel trusses allow for larger overhangs and clear spaces. The column structure charges orientation as the structure descends, allowing for the increase in window dimension and light to the lower levels. At level 04 structural transfer beams accommodate a change in block width at this point from an 18 metres floor depth to 15 metres above. Precast concrete soffits are cast as permanent formwork with cast in lighting and thermally isolated. Chilled slabs are incorporated into all roofs, these are inhabited with various soil depths and biodiverse roof finishes, bees, and solar panels. WANT TO

The digital version of this magazine includes access to exclusive galleries of architectural drawings.

The digital magazine is available to subscribers on passivehouseplus.ie & passivehouseplus.co.uk

A high-performance aluminium window system is used throughout the non-Fitzwilliam St facades. The system has a custom profile fin to the front and rear perimeters that act as closers to the cavity on both sides. Each 3 m bay is composed of a large fixed window, a solid side hung vent and an upper BMS actuated top hung vent.

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SELECTED PROJECT DETAILS

Client: ESB - Electrical Supply Board Ireland

Architects: Grafton Architects / O’Mahony Pike Architects

Sustainability consultants: BDP

Conservation architects: Shaffrey Associate Architects

Structural/civil engineers: O’Connor Sutton Cronin

Landscape architects: Bernard Seymour Landscape Architects

Mechanical/electrical consultants: BDP / Axiseng

Quantity surveyors: Linesight

Planning consultants: Tom Phillips & Associates

Fire consultants: MSA

Acoustic consultants: AWN Consulting Ltd

Façade consultants: Buro Happold

DAC consultants: Maurice Johnson & Partners

Project management: Lafferty

Health and safety: Arup

Ecology: Scott Cawley Ltd.

Main contractor: PJ Hegarty & Sons

Mechanical contractor: Leo Lynch

Electrical contractor: Designer Group

Airtightness testers:

Building Envelope Technologies

Thermal bridging modelling: Passivate

BREEAM (D&B): Eslar

Precast subcontractor: Techrete IRL

Windows subcontractor: Gunn Lennon Fabrications

Brick supplier: Janinhoff Klinker Manufaktur / Gillrath Ziegel & Klinkerwerk GmbH & Co. KG

Steel window fabricator/supplier:

MHB / The KCC Group

Granite Supplier: RyanStone

Metalwork: OMC Technologies Ltd

Specialist pointing Contractor: Oldstone Conservation Ltd

Superstructure concrete frame: Admore Group

Landscaping subcontractor: Peter O’Brien & Sons Landscaping Ltd

Roof: Crown Roofing Limited / Bauder Flat Roofs

Automatic opening vents: Alucraft Ltd

t/a William Cox

Tiles: Aston Crean Ireland

Fire doors and timber panels: Burke Joinery Limited

Partitions: Castle Group

Lifts: Kone (Ireland) Ltd

Precast Stairs: O’Reilly Concrete

Terrazzo: P J Ryan Terrazzo & Mosaic Spe

Screed: Floor Screed Ireland

Insulation: U-Value Insulation

Green roof: Crown Roofing Ltd

Architects and quantity surveyors: Aecom

Sustainability and BREEAM consultants: BDP

Mechanical/electrical and civil/structural

consultants: BDP

Audio visual: Hamilton Robson

Project management: Lafferty

Catering: QA design

Main contractor: Walls

Mechanical/electrical contractor: Jones Engineering Group

Air handling units: Systemair (ESB side) and Flakt Woods (Block A)

Air source heat pumps: Daikin (ESB side) and EICL (Block A)

Zero GWP transfer heat pump: Daikin

Phase change material: (Crystalair PCM)

Hot water heat pump (water-to-water):

Climaveneta via Flakt Woods

Grilles and diffusers: Entropic

Low energy kitchen canopies: Entropic (automatic cooking sensors and UV filtration to allow heat recovery)

Underfloor heating: FLV

Window actuators: Smoke Management Systems Ltd

6 port valves: Belemo Automation

Meeting room heat recovery unit: Flakt Woods

Fan coils (very low fan power units – also unusual as designed for single coils): Versatile.

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Building type: Large office block subdivided into two distinct offices, with a 22,343 m2 gross internal area block occupied by the ESB, and a 16,577 m2 commercial block.

Location: Fitzwilliam Street, Dublin

Completion date: February 2022

Budget: Approx. €150 m.

Environmental assessment method:

BREEAM Excellent

The LEED, WELL and DNGB methods were also used to inform the design. The building was used as a case study as part of an IGBC study of assessment methods.

Space heating demand: 7.7 kWh/m2/yr by detailed dynamic thermal simulation. Initial monitoring results imply the figure is realistic. Note that the majority of this heat is provided by recovered heat.

Heat load: 15 W/m2 by detailed dynamic thermal simulation. Initial monitoring results imply the figure is realistic.

Primary energy demand: 67.7 kWh/m2/yr using SBEM.

150 kWh/m2/yr using dynamic simulations.

The building operates 24/7, 365 days per year, and contains some functions that are not directly related to the building so typical office benchmarks must be used with caution. It is too early for monitoring results to give an accurate indication of performance, but initial usage implies a value between the figures above. Overheating: 0 per cent overheating from dynamic simulations.

The building embraces adaptive comfort and internal temperature limits are a complex function of external temperature. The traditional overheating criteria do not apply and a new dynamic, adaptive response is used.

The building is capable of achieving a set internal temperature, but it is allowed to adapt dynamically in the interest of both reducing energy and improving comfort.

Number of occupants: The ESB building can support up to 1,650 staff but actual numbers will typically be lower.

Energy performance coefficient (EPC): 0.83

Carbon performance coefficient (CPC): 0.84

Note that SBEM is not capable of considering many of the energy saving techniques used so the results from SBEM have limited meaning. The above EPC and CPC figures are relative to the 2017 version of Part L where the building was only required to comply with the previous version due to the date at which planning was achieved. It was however important to exceed the requirement of future Building Regulations at the time of design.

BER: A3 67.7 kWh/m2/yr.

Measured energy consumption: The operating time has not been long enough to establish accurate energy usage metrics.

At this stage data is only available for five months. The data implies a usage of approximately 83 kWh/m2/yr.

Airtightness: 2.5 m3/m2/yr

Thermal bridging: Passivate were employed to calculate thermal bridging results for all key details.

Energy bills (measured or estimated): No bills available.

Ground floor: Piled foundation with a U-value of 0.15 W/m2K. As there is a basement car park the ridged insulation is applied to the underside of the soffit. The ground slab and foundations

contained 70 per cent GGBS.

Walls: A mix of walls is used from the solid brick historic façade to the precast concrete walls (with 50 per cent GGBS). The average wall U-value was in the order of 0.15 W/m2K

Roof: Concrete slab (50 per cent GGBS) with ridged insulation to 0.16 W/m2K

Windows: A mix of windows with an average U-value of 1.2 W/m2K. Consideration was given to the use of triple glazing and it was shown that using it would result in a net increase in energy usage both from an embodied energy and a cooling perspective. The heating energy requirement is close to zero with the current design and that heat comes almost entirely from recovered cooling so there is no heat to save.

Heating system: A complex system of heat pumps. A Turbocor transfer heat pump is used to transfer loads between cooling and heating sides and an air source heat pump us used for net loads. The transfer heat pump can also operate in ground source mode. Hot water is provided by a water-to-water heat pump that recovers heat from cooling loads.

Ventilation: Hybrid ventilation. The main units are provided by Systemair in Block B and Flakt in Block A. The units are set up in an innovative variable volume variable pressure mode. The heat recovery wheel is a total recovery wheel (it can recover moisture in winter).

Water: Low flow fittings throughout including showers with a flow of less than 8l/min.

Waterless urinals. Ground water and rainwater recovery.

Electricity: 30 kW PV system.

Green materials: 70 per cent GGBS in the foundations and 50 per cent in the structure. A full life cycle assessment was carried out on the fit out which would be one of the first office projects to use the method.

COLD COMFORT

ARE IRELAND AND THE UK’S ENERGY RATINGS PREDICATED ON COLD HOMES?

Passive houses aside, attempts at low energy building have a long and inglorious history of using more energy than predicted, with a key reason being “comfort-taking”, where occupants take back the benefit of energy efficiency by cranking up the thermostat. But is it rather that energy ratings are assuming miserly heating use –and temperatures that fail to meet the requirements of a new EN comfort standard?

By Lenny Antonelli & Jeff Colley

The national dwelling energy calculation tools for Ireland and the UK may assess buildings in a way that assumes occupant discomfort, and that creates a ‘performance gap’ between a home’s designed energy performance and its real-world energy use.

The Dwelling Energy Assessment Procedure (DEAP), in Ireland, and the Standard Assessment Procedure (SAP), in the UK, both assume indoor temperatures which appear to be far lower than those recommended in a recent European standard for indoor environmental quality and occupant comfort.

For DEAP, this was pointed out to Passive House Plus by architect John Morehead. Having designed a detached dwelling in the passive house software, PHPP, Morehead then entered the building’s specification into DEAP.

At the suggestion of Passive House Plus, Morehead reduced the specification of all building fabric elements to the backstop levels in Part L of Ireland’s building regulations (also known as the nearly zero energy building, or NZEB, standard). Morehead specified the worst permitted U-values for the walls, roof, floor, windows and doors, as well as the worst allowable values for airtightness and thermal bridging. He also dramatically increased the size of the building’s notional solar PV array, to see if it would still comply with Irish regulations.

Despite the poorer performance of the building fabric, and the oversized PV array, the building still complied with the NZEB standard. Morehead then noticed that two figures in the ‘ht use’ tab of DEAP indicated that outside of heating hours, indoor temperatures would be uncomfortably low.

The mean internal temperature for unheated periods was given as 15.57 C, while the mean internal temperature for the whole heating season was just 16.5 C. DEAP assumes that, during heating hours, living areas (defined as the living room plus any adjacent spaces in open plan dwellings) are heated to 21 C, while bedrooms are heated to 18 C.

However, DEAP heating hours are only assumed to be eight hours per day from 1 October to 31 May. No heating is assumed at other times.

EN 16798 comfort standard

These temperatures fall below the thresholds for indoor environmental quality set in a recent European standard, EN 16798. The standard includes a table with four categories of indoor environmental quality for buildings: high, medium, moderate, and low (see table 1). The appendix to part two of EN 16798 then gives recommended indoor operative temperatures to correspond with these categories (see table 2).

The standard suggests that, even for the worst indoor environmental category for living spaces, bedrooms and kitchens, temperatures should not fall below 17 C. The standard says that this category is only intended for spaces that are “used for a short time of year” or spaces “with very short time of occupancy”.

Category two is suggested as the “normal level used for design and operation” of buildings, and this recommends a minimum indoor winter temperature of 20 C. However, John Morehead’s example shows that it may be possible to design NZEB dwellings that fall well outside this comfort recommendation. It should be noted that EN 16798 is a voluntary standard and is not yet referred to in any official Irish legislation or technical guidance.

SAP assumes low temperatures

SAP, the UK’s dwelling energy assessment software, appears to make similar assumptions as DEAP. Leading consultancy Elmhurst Energy examined the temperature profiles of new dwellings in England for Passive House Plus.

“The result of all of this is after looking through a number of Part L 2013 compliant buildings typically the mean internal temperature across the whole building ranges from around 17-18 C in the winter months to 20-21 C in the summer months,” the com-

pany’s new-build dwellings manager, Jason Hewins, said. This would put these buildings in the bottom two comfort categories, categories three and four, for dwellings.

In Ireland, the theoretical dwelling modelled by John Morehead does not appear to be an exception. Indeed, the DEAP files for example dwellings provided by the Department of Housing to show different ways of complying with Part L typically show mean internal temperatures for unheated periods, and for the whole heating season, (including periods when the heating system is switched off) of 17 or 18 C.

However, these sample dwellings have high ‘living area fractions’ of 25 or 50 per cent, indicating the proportion of the dwelling heated to 21 C during heating hours. Analysis of recently built dwellings in SEAI’s national BER database indicates that the mean living area fraction for detached houses built to the NZEB standard to date is 18.2 per cent, which would reduce the mean internal temperature of these dwellings even further. This indicates that a substantial proportion of newly built dwellings in Ireland may be assumed to be running at mean indoor temperatures that do not, or just barely, meet the lowest categories of indoor temperature recommended by EN 16798 .In response to a question from Passive House Plus about whether EN 16798 might be incorporated into DEAP, the Sustainable Energy Authority of Ireland (SEAI) told Passive House Plus that the EU’s Energy Performance of Buildings Directive is currently being revised, and that this may have an impact on BER calculation methods. “SEAI plans to commence this year a review to consider future changes to the methodologies. This would include consideration for EN 16798 and related calculation standards,” wrote SEAI programme manager Antonella Uras.

Operative vs dry bulb temperatures

SEAI had previously told Passive House Plus that because the EN standard gives “operative temperatures” (i.e., the temperature

The deep retrofit to College View in Wexford saw substantially higher heat energy use than predicted, likely due to the elderly occupants desire for consistent heat and high comfort levels

experienced by a person in the room) while DEAP uses “dry bulb temperatures (i.e., air temperatures), these figures could not be directly compared. Operative temperatures are a combination of the dry bulb temperature and the radiant temperature.

However, having consulted various experts on the topic, Passive House Plus understands that in well insulated buildings, unless there is a large area of glazing and thus high solar radiation, the difference between the operative and air temperature is very small.

There is concern about the extent to which building assessment tools such as DEAP and SAP may struggle to capture the actual temperatures to which dwellings are heated, potentially leading to a performance gap where buildings consume more energy for space heating than is initially projected. In reality, building occupants are likely to maintain indoor temperatures at a higher level than the 15-18 C assumed by DEAP during unheated hours, and thus energy consumption could turn out to be higher than predicted.

Issue 37 of Passive House Plus featured a case study of College View, a social housing retrofit scheme in Wexford, in which energy consumption was significantly higher for most dwellings than that projected by DEAP, in some cases between 25 and 50 per cent more. A post occupancy evaluation study carried out by the NZEB101 project subsequently found that many occupants were heating the dwellings to temperatures significantly higher than assumed by DEAP. For all but two of the dwellings, living room temperatures were above 20 C for 75 per cent of the time, and the warmest dwelling had median temperatures of between 23.4 C and 25.2 C across the four seasons.

This is a complex and technical subject and Passive House Plus welcomes any input from readers at jeff@passivehouseplus.ie •

Category Level of expectation

IEQI High

IEQII Medium

IEQIII Moderate

IEQIV Low

Explanation

Should be selected for occupants with special needs (children, elderly, persons with disabilities).

The normal level used for design and operation.

Will still provide an acceptable environment. Some risk of reduced performance of the occupants.

Should only be used for a short time of the year or in spaces with very short time of occupancy.

Table 1: Categories of indoor environmental quality.

Residential buildings, living spaces (bed room’s, kitchens, living rooms, etc.)

Sedentary activity ~1,2 met

Residential buildings, other spaces (utility rooms, storages, etc.)

Standing-walking activity ~1,5 met

Offices and spaces with similar activity (single offices, open plan offices, conference rooms, auditoria, cafeteria, restaurants, class rooms)

Sedentary activity ~1,2 met

I 21,0 - 23,0

II 20,0 - 24,0

- 25,5

- 26,0

III 19,0 - 25,0 22,0 - 27,0

IV 17,0 - 25,0 21,0 - 28,0

During the between heating and cooling seasons (with Өrm between 10 and 15°C) temperature limits that lie in between the winter and summer values may be used. Air velocity is assumed < 0,1 m/s and RH ~40% for heating season and 60 % for cooling season

Table 2: The mean design operatice temperature can vary from the values shown to take account of e.g., local custom or a desire for energy saving so long as the within-day variation from the design temperature is within the given range, and the occupants are given time and opportunity to adapt to the modified design temperature.

During between heating and cooling seasons (with Өrm between 10 and 15°C), adjusted upper and lower temperature limits may be used that lie in between the winter and summer values mentioned.

Marketplace News

Partel develops two new fire-rated breather membranes

Partel, a leading manufacturer of airtight and windtight membranes, has developed two new fire-rated breather membranes that exceed current fire safety regulation levels for high-rise and high-risk buildings: Exoperm Duro A1 and Exoperm Mono Duro A2.

The high-performance membranes are designed to achieve the highest levels of fire performance while also protecting the building structure by allowing vapour to diffuse from within the assembly towards the exterior, keeping the internal components of the wall dry, preventing ‘thermal bypass’ of external air through the insulation, and performing the secondary task of weather protection.

Suited to offsite and onsite construction, and commercial or residential projects, both solutions are fully independently certified and tested in accordance with EN13501-1. The membranes are compliant with Document B Fire Safety and are suitable for use in a range of external wall types, especially in high-rise buildings or those that pose a greater risk of fire safety.

Regulations state that membranes used as

part of an external wall construction above ground level must achieve a minimum of Class B-s3, d0 – a result well below the A2 or A1 levels.

“At Partel, we are proud to introduce our additional fire-rated breather membranes, Exoperm Duro A1 and Exoperm Mono Duro A2, which go beyond current fire safety regulations and complement our limited combustible vapour control layer Izoperm Plus A2,” said Partel director Hugh Whiriskey. “We are committed to developing advanced membranes that will help to facilitate offsite manufacturers, contractors, and architects create façades that are fully non-combustible, and sustainable.”

The newly engineered breather membranes incorporate advanced technology with an integrated glass fibre fabric to deliver the highest fire performance levels and protection. Exoperm Duro A1 is non-combustible and suitable for use on closed joint façades. Alongside fire performance, Exoperm Duro A1’s technical attributes ensure long-term protection of the assembly, with a highly vapour open

Proctor launches range of online services

Sustainablebuilding product supplier A.

Proctor Group has introduced a new online U-value calculator, condensation risk analysis software, and members area with a range of technical supports available to architects, contractors, and customers.

The changes to ‘Conservation of fuel and power: Approved Document L’, which came into effect in June 2022, are intended to increase further the standards for the energy performance of new and existing buildings. In addition to the focus on the target of reducing carbon emissions, further performance improvements impact the approach to airtightness, thermal bridging, and insulation.

To assist architects, designers, developers, and contractors to accurately carry out assessments to ensure compliance with the latest requirements of the Part L building regulations, the A. Proctor Group has introduced dedicated U-value and condensation risk analysis software. The company described the software as “an essential online tool for meeting the new standards and improving the energy performance of new

and existing buildings.”

U-value calculations are conducted in accordance with BRE443: Conventions for U-value Calculations, and can be submitted with your building control applications to demonstrate compliance. The calculations are to BS6946 2017 including Annex C (Surface Resistances), Annex D.1 & D.2 (Thermal Resistance of Airspaces) and Annex F (Correction to thermal transmittance). The calculations also meet ISO 13370 2017 - Thermal performance of buildings - Heat transfer via the ground. U-values for light steel-frame construction are calculated to BRE Digest 465.

Proctor’s condensation risk analysis is calculated to ISO 13788 (Glaser method) – a steady state method as opposed to dynamic methods such as Wufi – supporting infinite condensation planes. The tool includes automated external environment corrections for suspended floors and slab on ground floor element types.

The company is also offering postcode-specific climate data, meaning the condensation risk will be calculated based

Sd value of 0.03 m, along with resistance to water penetration and dimensional stability.

Exoperm Mono Duro A2 is an innovative airtight yet vapour permeable façade membrane, based on monolithic technology. This is Class A2-s1,d0, guaranteeing limited-combustibility, absent or very limited smoke emissions, and no burning droplets. It is suitable for use on open or closed joint façades and balances airtightness, moisture management and secondary weather protection with fire performance.

For more information visit partel.ie or partel.co.uk •

on up to date 20-year average temperature & humidity data for the project’s postcode. Local climate data is a requirement of both BS5250 & ISO 13788.

Users will be able to print full projects to PDFs, and add custom air layers with low emissivity and ventilation, add custom fixing profiles, adjustable return periods and external and internal environments.

A new members area has also been introduced to the A. Proctor Group website that enables architects, designers, contractors, and clients to access a broad range of technical resources. Registered members will have access to webinars on critical topics, with personalised CPD certification for each. A full suite of brochures and product documents including technical properties and characteristics is available for download from the members area.

Visit www.proctorgroup.com to register for the members area, access the U-value calculator and condensation risk analysis tools. •

Beattie Passive lands frameworks and ISO certification

Pioneering passive house modular housing provider Beattie Passive has had a busy start to 2023: being named a supplier on two multibillion pound frameworks for new build and retrofit, achieving certifications for environment, quality and health and safety, and launching a new website.

The first company in the UK to be certified for a complete build system by the Passive House Institute, Beattie Passive has been named as a supplier for Lot 3 Residential Properties and Lot 6 Thermal Efficiency Upgrades on Crown Commercial Service’s (CCS) Offsite Construction Solutions framework – and for Category 1 modern methods of construction (MMC) on the Offsite Homes Alliance (OSHA)’s £2 billion off-site national modular construction framework.

The OSHA framework is administrated by Great Places Housing Group to supply homes to its 23 members and to future new members of the alliance.

CCS supports the public sector to achieve maximum commercial value when procuring common goods and services. In 2021/22, CCS helped the public sector to achieve commercial benefits equal to £2.8 billion.

Commenting on the CCS appointment, Beattie Passive MD Ron Beattie said: “This is clearly brilliant news for us as a business, but it is also indicative of the government’s commitment to offsite construction, which is tremendous news for everyone involved in the sector, including our partners and suppliers.

“We have a strong proposition, because we build to passive house standards and we’ve already delivered a number of net zero housing schemes in England and Wales. We believe that modular housing, built offsite to passive house standards, will help to ease the housing crisis and tackle the climate emergency, while raising building and living standards.”

Nathan Beattie, commercial operations at Beattie Passive, added: “We’re also pleased to be named on Lot 6 (thermal efficiency upgrades) because of the urgent need to improve the energy efficiency of UK homes. Given that 80 per cent of the buildings we’ll be using in 2050 have already been built, we’re very keen to use our proven deep retrofit system to decarbonise the nation’s existing housing stock.”

Selected onto the OSHA framework based on technical competence, price and commitment to social value, Beattie Passive will support in the delivery of extensive development programmes and collective am-

bitions to tackle the housing crisis.

Matthew Harrison, chief executive of OSHA member Great Places Housing Group, said: “We’re delighted to be working with Beattie Passive on the new OSHA framework. We’re confident they will be able to work with us and the OSHA clients in delivering the sector’s extensive development ambitions. We are now looking forward to mobilising the framework and working together on new projects to realise our ambitions of delivering much-needed affordable homes.”

ISO certifications

Meanwhile Beattie Passive has achieved UKAS ISO 9001, ISO 14001 and ISO 45001 certification, reaffirming the Norwich-based company’s commitment respectively to quality management, environmental responsibility, and occupational health and safety.

“We’re incredibly proud to have achieved these certifications because they demonstrate our commitment to quality, sustainability and safety,” said Ron Beattie. “We always strive to provide the highest standards of quality to our customers, while minimising our environmental impact and safeguarding the health and safety of our employees.”

Beattie Passive chief commercial officer Jack Randall said: “Our aim is to increase awareness of passive house and make it more accessible to public sector organisations that want to tackle fuel poverty, raise living standards and achieve their net zero ambitions. Our patented, passive house-certified build system combines all the energy efficiency, comfort and carbon-saving benefits of the passive house standard with the speed and versatility of volumetric modular construction. It’s a very compelling solution to many of the challenges facing the housing sector and the construction industry.”

New website

Since its inception in 2009, Beattie Passive has built over 450 homes to the passive house standard. The company has recently launched a new website featuring a host of case studies, ranging from net zero modular social housing projects through to relocatable modular homes for the homeless, custom-built housing developments, and even deep retrofits for social housing providers. Last year, Beattie Passive handed over its largest and most ambitious project to date: a net zero-rated, passive house “plus” certified housing development for Cardiff Council, which was published in issue

43 of Passive House Plus. The company picked up ‘Building Performance Pioneer of the Year’ award for the project at the Offsite Awards, and was also recognised at the Inside Housing Awards and the Welsh Housing Awards for the affordable social housing scheme it delivered in Llangan, Wales, with its flying factory partner, Canna Developments, for Newydd Housing Association.

Another Beattie Passive project, named Mere House, won the RIBA East Award for Small Project of the Year 2022. As a result, it was included on the shortlist for the prestigious RIBA House of the Year Award and appeared on episode four of Grand Designs: House of the Year, with Kevin McCloud.

Commenting on the new website, Beattie Passive chief commercial officer Jack Randall said: “We’ve been building homes to the passive house standard for over a decade. The benefits are very compelling. It’s extremely energy efficient and can reduce heating demand by up to 90 per cent. Housing providers are embracing the standard to combat fuel poverty, but the other key thing about passive house is that it raises building and living standards by tackling damp and mould and improving interior air quality.

“Our new website clearly conveys all these benefits and shows what we’ve already achieved for our clients. By combining the energy efficiency, comfort and carbon-saving benefits of the passive house standard with the speed, precision and versatility of volumetric modular technology, we can build high quality, energy-efficient net zero homes at the pace and scale required to ease the housing crisis and respond to the climate emergency.”

For more information visit https://www. beattiepassive.com •

(above) Beattie Passive MD Ron Beattie.

A movement for change

We focus on:

• Supporting and guiding members in improving knowledge and practice of environmentally-conscious design and construction.

• Influencing the national and local agendas as a movement for change.

• Capturing experience, insights, exemplar practice and hard data on building performance from pioneers, early adopters

Membership benefits

• Access to industry experts, technical authors, technical webinars, discounts on cutting edge designer software and events with strategic partners.

• Join as a company and key employees become members.

• Join as an educational establishment and staff and students become members.

• 20% discount on Passivhaus Trust membership which is available to everyone upon joining the AECB.

and expert practitioners in our community.

• Communicating with members, wider industry and the public through publications, events, training courses, the AECB Knowledge base.

• Providing guidance on the use of the AECB Building Standard and the AECB Retrofit Standard.

AECB Annual Fees Categories

Full time student / Retired / Low Income (No website listing)

Supporting Individual (No company membership or website listing)

Sole trader Small company (Up to £250k turnover)

Medium company (Between £250k - £1m turnover)

• Passive House Plus magazine subscription.

• Access to CarbonLite training courses.

• Discount on Passive House training courses.

• Listing in members directory and access to posting.

• News on the AECB website.

• Setting the Standard magazine

Large company (Up to £10m turnover)

Largest company (Over £10m turnover)

Local Authority/ Housing Association

Educational Institutions

Eco Slate boost circularity credentials with UK production

Sustainable roof product supplier Ecoroofing Systems Ltd has boosted its circularity credentials – by opening a UK-based processing plant.

The new plant processes recovered polymer sourced from within the UK to provide the base material for the flexible roof slate, Eco Slate. The BBA certified slate was previously made in China but two years ago Ecoroofing Systems took the decision to bring manufacturing to the UK. This final step brings the sourcing and processing of the base polymer to the UK rather than importing from overseas processors.

The new processing plant is located at the moulding factory and is capable of processing up to 700,000 tonnes of waste plastic per year. The source material is laminate from all forms of safety glass which is considered a problematic waste stream. The process removes the glass (for recycling) and pelletises the waste plastic so it can be moulded into the Eco Slate, meaning waste is diverted from landfill.

Eco Slate is a flexible and long-lasting roof covering which provides a natural and authentic slate appearance in a range of colours including traditional grey, old world red and Cumbrian green. Easy to install, fully standards-compliant, cost-effective, and sustainably manufactured in the UK from recycled material, the slate is used on board roofs, and is certified down to roof pitches of 10°. The slate bonds together over time to form a solid membrane. It is class A fire-rated, flexible, and lightweight (typically around 11 kg per m2) and can be used on both ridges and hips. The slate is unbreakable thus eliminating waste from breakages from transport, storage, or handling. The slate’s versatility means very few offcuts and much less waste during installation which is a simple, quick, and straightforward procedure, up to four times faster than traditional slates. The slates are virtually maintenance-free and create a solid pliable membrane with a warranty of over 40 years.

For more information visit www.ecoroofingsystems.co.uk •

(Below) Eco Slate comes in three colour options, traditional grey, old world

What goes around comes around - why the history of refrigeration points to the future of heating

As efforts to decarbonise buildings gain pace, heat pumps powered by an increasingly clean grid are looking like an irresistible force. While reducing emissions from operational energy use rightly remains front and centre, embodied carbon is the next target – including the heat pump’s refrigerant. Toby Cambray goes back to refrigeration’s beginnings to find a route to a low carbon future.

Regular readers will recall that heat pumps and their role in retrofit have been a recurring topic in this column. Initially I suggested that it was time to put the sacred cow of ‘fabric first’ out to pasture, or at least think about its importance in the context of national retrofit, heated by heat pumps via an increasingly low carbon grid. We must still insulate, for comfort and health, and indeed to minimise infrastructure costs, but heat pumps are at a higher level of readiness to scale out, and if done thoughtfully, need not preclude a subsequent fabric retrofit.

Lloyd Alter then queried whether there was an issue with oversized heat pumps following a heat pump first, fabric later retrofit: does this cause short cycling and a loss of efficiency? The answer is not really, especially with modern inverter-driven heat pumps, assuming everything has been otherwise well-designed and commissioned. That said, dramatically oversized heat pumps often underperform. While assumption is the mother of all cockups, this is a pragmatic approach that is reflected in the new AECB CarbonLite Level 1 Retrofit Standard. On the Zero Ambitions podcast Lloyd recently drew attention to the issue of upfront carbon with heat pumps, in particular those nasty refrigerant gasses. So, we’re going deep on refrigerants and refrigeration.

If you were able to engineer suitable compressors, valves and heat exchangers, pretty much any fluid could be used as a refrigerant. You start in the gas state, squeeze it up to high pressure (which makes it hot), take the heat out (which makes it condense) and use it in your heating system. Then let the pressure off (which makes it expand and cool), and it sucks in heat from the outdoor air (which makes it boil back into a gas), and round you go again.

In principle this could happen with all fluids. It’s just a matter of creating the right

combinations of temperatures and pressures. This is much more practicable (in terms of the necessary pressures) and useful (in terms of resultant temperatures) for a group of substances we call refrigerants. The need for fluids with just the right behaviour under temperature and pressure is at the heart of the challenges refrigeration engineers have faced for the last 200 years: it turns out that many of the good candidates have unfortunate side effects. But let us start at the beginning.

A condensed history of refrigeration

Natural scientists including Benjamin Franklin and Michael Faraday had experimented using changes in pressure to create cooling effects as early as 1758. In the 19th century USA, the ice trade rapidly developed, where ice was transported from the north to warmer climes, where it was used in simple ice boxes and cold storage; the benefits to the food industry led to the rapid growth of the ice trade. A passive house specific aside – large blocks of ice melt surprisingly little during transport due to a good form factor, when compared to say an ice cube.

James Harrison (1851). These early advances employed ether, ammonia or alcohol as the refrigerant fluid. The refrigeration industry burgeoned with demand from the food and beer industry. Somewhat ironically, the refrigeration industry’s out-competing of the ice industry was helped by concerns about ice tainted by environmental pollution. This competition was also the origin of a unit of refrigeration still used in the US – the ton. Refrigeration salesmen equated the cooling capacity of their equipment to the equivalent daily weight of ice the customer could avoid buying. One ton of cooling capacity is about 3.5 kW, the latent heat of fusion of a ton of ice over 24 hours.

Until 1930, refrigeration remained an industrial process. Machines were big, expensive and dangerous. The fluids in use were often flammable, toxic or both. Methyl chloride and sulphur dioxide were widely used, and explosions and leaks of toxic gasses were not uncommon. Industrial refrigeration was therefore used to produce ice for consumers who used it in their homes instead of ‘natural’ ice. In response to safety concerns, in 1930, the Frigidare company first synthesised Freon which, being non-

The vapour compression cycle, the principle on which the overwhelming majority of heat pumps and indeed most refrigeration in use today works, was first proposed in 1805 by Oliver Evans. Patents for designs were sought by Jacob Perkins (1834), John Gorrie (1842), Alex Twining (1850) and

toxic and non-flammable, paved the way for the mass adoption of domestic refrigerators. Freon is a trade name for a whole family of compounds that chemists call chlorofluorocarbons (CFCs).

In the 1970s, it was realised CFCs were damaging the ozone layer and phase-out

The vapour compression cycle – the principle on which the overwhelming majority of heat pumps work was first proposed in 1805 by Oliver Evans.

began with the 1987 Montreal Protocol. Specifically, it was the chlorine that caused the problem. This agreement is sometimes championed as an example of international agreement on environmental pollution. It is an ongoing tragedy that we have not achieved the same agreement with respect to fossil fuels. One reason for the success of the Montreal Protocol was that it has been relatively straightforward to introduce replacements for CFCs and their ilk. CFCs were phased out in favour of hydrofluorocarbons (HFCs) and the ozone layer has been mostly recovering ever since.

It is less commonly known that many refrigerants have a disastrous impact on global warming, on top of the ozone layer issues associated with pre-1987 compounds. HFCs are particularly powerful greenhouse gasses. To set this in context it is useful to introduce a metric called global warming potential (GWP), which measures the impact of a gas on the greenhouse effect, relative to CO2. One kg of gas with a GWP of 2 has the same climate change impact as two kg of CO2. Methane is a useful point of reference here because its release from livestock, permafrost, so-called fugitive emissions and so on, is a significant issue with respect to climate change. Methane has a GWP of 28 – dramatically more impactful, per kg emitted, than CO2

A complication with the definition of GWP is that some gasses break down in the atmosphere. CO2 is quite stable (one of the reasons the greenhouse effect is a problem), whereas methane is removed, on average, in around 12 years. The time frame over which the GWP is calculated therefore influences the value significantly. Estimates are often based on 100 years. This begs another question; given the climate emergency is upon us, and the next 10 years are crucial, what is an appropriate timescale to use for

making these decisions? Furthermore, the GWP does not usually include the up-front carbon. Although there’s plenty in the atmosphere, even pure CO2 (which, spoiler alert, is a potentially useful refrigerant) has a carbon footprint because it takes energy to isolate it.

If you were shocked at the relative power of methane to induce climate change, wait till you hear about refrigerants. Until very recently, and to some extent even now, two of the most common refrigerants in heat pumps were R-134a and R-410a. While neither of these gasses damage the ozone layer, their GWP100 values are 1,430 and 2,088 respectively. For context, heating an average size passive house dwelling (and its domestic hot water) with an air source heat pump (ASHP) would cause the emission of roughly 350 kg. A domestic ASHP might contain one or two kg of refrigerant, so a total leak would be equivalent to say 3.5 tonnes of CO2. Very roughly, a bad leak of an older refrigerant is equivalent to 10 years of operational emissions in a very low energy dwelling.

Reasons to be cheerful

In 2016, the signatories to the original Montreal Protocol agreed the Kinshasa Amendment, to phase out HFCs due to their significant impact on the climate. The UK for example is phasing down HFCs by 79 per cent from 2012 levels by 2030, via a combination of reporting regulations and quotas. This intervention has spurred the rapid development of alternatives in heat pumps, which in some respects brings us full circle. In the early days of refrigeration, engineers were using what we would call today natural refrigerants – as opposed to those that must be synthesised. Today, natural refrigerants are once more in vogue because they mostly have no impact on the ozone layer,

and much smaller, if any influence on global warming. These gasses are often unremarkable substances when you look up the meaning of the somewhat confusing R- numbers beloved of engineers. Available today are small ASHPs containing R-32 (Difluromethane, GWP of 677), R-744 (CO2, GWP of 1) and R-290 (Propane, GWP <10).

While there is no such thing as a free lunch, the disbenefits and compromises necessary for these gasses to work are not unreasonable. Propane is of course flammable and is also somewhat toxic; R-32 is flammable and is moderate as a GHG. Flammability has been a sensitive topic in the UK since June 2017, but one could argue such gasses are acceptable in monobloc systems where the gas is entirely outdoors. R-32 also must be held at high pressure to achieve the temperatures necessary for a domestic heat pump. As well as being more costly to engineer, the high pressure makes leaks more likely. This is a key challenge with ultra-high pressure CO2 based heat pumps, although leakage is much less of a climate issue due to the low GWP. As well as the high pressures, natural refrigerants generally have a lower specific cooling capacity than their more harmful synthetic counterparts. This means you need more of the particular refrigerant to deliver each kW of heating (or cooling), but also you will need physically larger compressors and heat exchangers. This will increase upfront carbon (more copper, aluminium and steel) as well as costs. As much as I’d like to, I’ve not undertaken an extensive market survey scrutinising and comparing EPDs, but I suspect these costs are acceptable and tend to be outweighed by the environmental impacts of older refrigerants so we should not begin a campaign for the overturning of the Montreal Protocol.

Ten years ago I tried and failed to buy a CO2 heat pump for our office, ending up with an R-134a device. Such things existed but not on the market in the UK. Today the landscape is very different – the Kinshasa Amendment is ratified, and the industry is loudly proclaiming its innovative developments in the field of natural refrigerants. This is to be welcomed, but we should bear in mind that the change was largely driven by boring old regulations. Thank heavens for red tape. The move towards less harmful refrigerants is not entirely without issues, although these are largely within the purview of manufacturers. On the whole though these are reasons to be cheerful. n

Toby Cambray is a founding director at GreenGauge and leads the building physics team. He is an engineer intrigued by how buildings work or fail, and uses a variety of methods to understand these processes.

(above) Patented in 1859, Ferdinand Carré’s ice making device, an absorption refrigerator that used ammonia as the refrigerant.