The Green Building Handbook Volume 9

The Green Building Handbook

T A M South Africa Volume 9

Materials and Technologies

&TECH 09

9

780620 452403

R150.00 incl. VAT

ISBN 9-780620-452403

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THE GREEN BUILDING MATERIALS AND TECHNOLOGIES HANDBOOK

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THE GREEN BUILDING MATERIALS AND TECHNOLOGIES HANDBOOK

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FOREWORD

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he South African Institute of Architects (SAIA) is in support of sustainable design and construction, a fundamental component of which is the specification of materials and technologies, and as such SAIA is happy to provide this foreword for the Green Building Materials and Technologies Handbook.

This peer reviewed publication is a further contribution to the overall body of knowledge on the subject of sustainable design, and we have no doubt that it will be of value to our members and indeed to all specifiers and decision-makers grappling with the technical and often conflicting sustainability arguments presented by suppliers.

We hope you will find this publication beneficial in your architectural practice.

Yours faithfully

Obert Chakarisa Chief Executive Officer On behalf of SAIA

THE GREEN BUILDING MATERIALS AND TECHNOLOGIES HANDBOOK

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The Green Building Handbook

South Africa Volume 9

Materials and Technologies

EDITOR Llewellyn van Wyk

PROJECT LEADER COVER IMAGE Louna Rae and Partners: BMW Head Office Boogertman

PROJECT MANAGERS ASSISTANT EDITOR Nabilah Hassen-BardienLouna Rae Nabilah Hassen-Bardien,

ADVERTISING EXECUTIVES Munyaradzi Jani Tendai Jani

CONTRIBUTORS Llewellyn van Wyk, Benson Wekesa, Cathy Mphahlele, Joe Mapiravana, Naalamkai AmpofoAnti, Sihle Dlungwana, Zonke Dumani, Paul Marais, Peter Kidger , Jeremy Gibberd, John Barnard PEER REVIEWERS Naalamkai Ampofo-Anti, Llewellyn van Wyk, Joe Mapiravana, Graham Young DISTRIBUTION Edward Macdonald CLIENT LIASON MANAGERS Lizel Olivier Natasha Keyster

CHIEF EXECUTIVE Gordon Brown DIRECTORS Gordon Brown Andrew Fehrsen Lloyd Macfarlane EDITORIAL ENQUIRIES LvWyk@csir.co.za PUBLISHER

www.alive2green.com

The

The Sustainability Series Of Handbooks PHYSICAL ADDRESS: Alive2green Cape Media House 28 Main Road Rondebosch Cape Town South Africa 7700 TEL: 021 447 4733 FAX: 086 6947443 Company Registration Number: 2006/206388/23 Vat Number: 4130252432

Sustainability and Integrated REPORTING HANDBOOK South Africa 2014

ISBN No: 978 0 620 45240 3. Volume 7 first published February 2012. All rights reserved. No part of this publication may be reproduced or transmitted in any way or in any form without the prior written consent of the publisher. The opinions expressed herein are not necessarily those of the Publisher or the editor. All editorial contributions are accepted on the understanding that the contributor either owns or has obtained all necessary copyrights and permissions.

IMAGES AND DIAGRAMS: Space limitations and source format have affected the size of certain published images and/or diagrams in this publication. For larger PDF versions of these images please contact the publisher.

DISTRIBUTION AND COPY SALES ENQUIRIES distribution@alive2green.com INTERNATIONAL FRANCHISE ENQUIRIES info@alive2green.com PRINTER FA Print ADVERTISING ENQUIRIES sales@alive2green.com

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DEAR READER You are reminded that, under the provisions of the South African Council for the Architectural Profession (SACAP) Board Notice 31 of 2009, registered architectural professionals are entitled to claim SACAP Category Three CPD credits for self-study according to the value stipulated in the Board Notice. Claims for this activity must be verified.

Note: The conditions related to SACAP renewal of professional registration and CPD compliance are amended

by SACAP from time-to-time. SACAP-registered persons are advised to make ensure that, if a Category Three CPD claim is contemplated for reading this manual, such reading will comply with SACAP CPD conditions which are in force at the time..

DISCLAIMER: Neither Alive2Green nor the South African Institute of Architects warrants that any Category three CPD claim will be accepted by SACAP. PEER REVIEW Alive2green has introduced and is committed to peer reviewing a minimum number of published chapters in certain Sustainability Series handbooks.

The concept of Peer review is based on the objective of the publisher to provide professional, academic content.

This process helps to maintain standards, improve performance, and provide credibility.

ALIVE2GREEN PEER REVIEW PROCESS The Publisher and the Editor allocate a reviewer to an article and then send it to the reviewer who is well acquainted with the topic. Reviewers return an evaluation of the work to the Editor, noting weaknesses or problems along with suggestions for improvement. The Editor notes the reviewer’s recommendations and will either publish the article without changes, request that the author amend the article in accordance with recommendations or reject the article but encourage revision and invite resubmission.

The Editor evaluates reviewer submissions and is under no obligation to accept recommendations. The Editor may also add his or her opinions and recommendations to those of the reviewer before passing these back to contributors.

Peer reviewed articles may not necessarily have incorporated all recommendations made by the reviewer but are likely to have been amended from the original version.

Alive2green is proud to have embarked on the journey of peer review and now strives to achieve certain objectives in this process which include, but are not limited to: •

Extremely high standards of published material

•

Acceptance of handbooks in academic institutions, including as prescribed text books

•

Increased publicity and exposure for handbooks in global academic circles

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Increased exposure for contributors and editors within academic, industry and peer-review circles

•

Increased quality of learning texts for Alive2green online learning modules which arebased on handbook content.

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Relevant and extensive coverage for advertisers within the handbooks and online.

The

Sustainability and Integrated REPORTING HANDBOOK South Africa 2014

EDITOR’S NOTE

Llewellyn van Wyk Editor

T

he Green Material and Technology Handbook aims to develop and disseminate information with regard to sustainability and resilience building.

While many worthwhile initiatives exist to promote sustainability and green building, transformation will be driven forward when technologies are used to significantly enable the implementation of new sustainable and resilient solutions.

In conceptualising the content of this Handbook, consideration is not just given to the new. Too often we view ‘new’ technologies as the only technologies worthy of consideration, whereas there are traditional and established technologies which have been forgotten about but which are still effective, such as the use of wetlands for waste water treatment.

In addition, this Handbook does not tout technologies as the saviour of our time: I am well aware that technology is but one instrument to use in the movement toward

sustainable and resilient human settlements.

Policy, leadership and appropriate human behaviour are equally important.

What this Handbook therefore sets out to do is to expose readers, decisionmakers, designers and those interested in sustainability to as full a range of technologies and materials as is possible. In doing so this Handbook will not endorse any one technology or material, but will strive to share technology and material development and, wherever possible, support this with research and case studies.

As noted in this handbook Reardon and Downton (2013:2) argue that “there is no single best solution.” Any combination of materials should be assessed in light of a range of factors to arrive at the most appropriate compromise. Every application is unique and should be individually evaluated. Exceptions are the norm — particularly in innovative design solutions.

Reardon and Downton (2013:2) recommend that decisions should also “be guided by life cycle assessment, which is able to take into account a material’s environmental emissions and depletions from ‘cradle to grave’: source, extraction, manufacture, operating performance and end of life disposal or reuse.”

I trust that this Handbook will add value to those involved in the support and development of sustainability and resilience-building.

SINCERELY

Llewellyn van Wyk Editor

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CONTRIBUTORS LLEWELLYN VAN WYK

He joined the Council for Scientific and Industrial Research in 2002 where he is a Principal Researcher in the Building Science and Technology Competence Area of the Built Environment Unit. Llewellyn has delivered several keynote papers at international and national conferences and workshops, and is the author of a number of published papers on the subject of sustainability and the constructed environment. He has contributed book chapters to a number of international publications. He has received a number of design and best paper awards for his work as an architect and researcher.

DR. BENSON WEKESA

Dr Wekesa is the Technical Group Leader CSRI, Built Environment Unit, AgrĂŠment South Africa. He has a doctorate, MSc and BSc hons degrees in civil engineering. He is a registered professional structural engineer and accomplished lecturer, researcher and mentor. He has published in peer review journals and conference proceedings.

JEREMY GIBBERD

Jeremy is an Architect with interests in sustainability, inclusion, sustainable built environments, community and education buildings. He has developed a range of tools, guides and training for government, the private sector and the UN on urban sustainability, sustainable buildings, sustainable facilities management and sustainable materials.

Jeremy has worked in a range of roles within the built environment in Africa, the USA and the UK .

DR. JOE MAPIRAVANA

Joe is a Materials Engineering Specialist. He is the Principal Researcher and Research Group Leader for the Building and Construction Materials and Methods at the CSIR.

JOHN BARNARD

Studied B Eng (Civ) at University of Pretoria, followed by an Honours degree in Structural Engineering (UP), and a Marketing Management diploma at Unisa.

Followed a career in marketing management at Iscor/ArcelorMittal. Joined the SA Institute of Steel Construction in 2006, specifically to develop the Light Steel Frame Building Industry in RSA.

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CONTRIBUTORS NAA LAMKAI AMPOFO-ANTI

Naa was born and educated in Ghana. She practised as an Architect in Ghana, Nigeria and Cameroon before immigrating to South Africa in 1990. She joined CSIR BE in 2005 and currently holds the position of senior researcher. Her research speciality is the use of Life Cycle Assessment (LCA) methodology to evaluate the environmental performance of buildings and building materials.

PAUL MARAIS

Paul has practised sustainable architecture since 1991 and is currently an academic associate at Cardiff Metropolitan University undertaking a Doctorate in Ecological building practises, researching rammed earth construction techniques. He is researching both the acceptability of appropriate technologies as well as cost effective construction methods, while working as a practising Architect and sustainability consultant.

PETER KIDGER

Peter Kidger is Director of Marketing at Corobrik. The pursuit of more energy efficient built environments has led to his engagement with considerable research to better understand the comparative performance of different wall construction types and the contribution of brick and brickwork for achieving sustainable outcomes.

SIHLE DLUNGWANA

Sihle is a Research Group Leader at the CSIR’s Built Environment Research Unit, specialising in research on small and medium enterprise (SME) development, their take-up of innovative technologies as well as their sustainable participation in the green construction economy of South Africa.

NOZONKE DUMANI

Nozonke Dumani has completed both BSc and MSc in Chemical Engineering at the University of Cape Town and is currently working at CSIR in the Built Environment unit as candidate researcher.

THE GREEN BUILDING MATERIALS AND TECHNOLOGIES HANDBOOK

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CONTENTS 1

Overview Of Certification Trends For Innovative Building ??????? (Ibts) In South Africa Technologies C. ??????

Mphahlele and Dr. B Wekesa

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Cradle-To-Gate Life Cycle Greenhouse Gas Emissions Of South African Major Building Materials Nozonke Dumani

42 26

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The Science, Technology And Innovation/Sustainability Nexus Llewellyn van Wyk

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Light Steel Frame Building As A Green Material And Technology John Barnard

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54

18 24

54 68

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18 24

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EVAPCO

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CONTENTS 36

78

86

102

5

???????Harvesting Rainwater ??????

Jeremy Gibberd

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The Applications Of Sisal Fibre-Based Materials In The Built Environment Sihle Dlungwana1, Joe Mapiravana2, Naa Lamkai Ampofo-Anti3 and Nozonke Dumani4

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Clay Brick Wall Constructions For Highest Thermal Performance In The Six Climatic Zones Of South Africa Peter Kidger

The Use Of Rammed Earth For House Construction In South Africa Paul Marais

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66

82 86

98

102

116

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ASSURING

Quality HOMES

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•

he National Home Builders Registration Council (NHBRC) is a statutory body with the main responsibility of providing protection in terms the Housing Consumer Measures Act, 1998 (Act No 95 of 1998). Its mandate is to provide protection

•

and to regulate the home-building industry.

•

The mandate of the NHBRC Chapter 1 of the Housing Consumers Protection Measures Act, 1998 (Act No 95 of 1998) as amended, prescribes the mandate of the National Home Builders Registration Council. The Act states the objectives of the council as follows:

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•

• •

To establish and to promote ethical and technical standards in the home-building industry To improve structural quality in the interest of housing consumers and the home-building industry To promote housing consumer rights and to provide housing consumer information To communicate with and to assist homebuilders to register in terms of this Act To assist home builders, through training and inspection, to achieve and to maintain satisfactory technical standards of home building To regulate insurers contemplated in section 23(9)(a) To achieve the stated objectives of this section in the subsidy housing sector

NHBRC products and services products (VFPs) and services. These are: • Enrolment of new homes • Home-builder registration • Home-building inspections • investigations • Home-builder training and development • Home-building dispute resolution • Litigation and legal advisory services • Geo-technical and materials engineering Enrolment of new homes New home builds need to be enrolled with the NHBRC before construction commences. With the enrolment of a home comes the necessary engineering input from competent persons that assist the home builder to take the neces- sary precautions in structural design, to ensure that is issued to all enrolled homes.

When a house is enrolled, the NHBRC will conduct a minimum of four inspections on the home and deal with complaints and noncompliance during construction.

The enrolled home will be covered for years by the NHBRC warranty scheme on major structural defects, from the day of occupation.

opmental activities to emerging home builders, to assist home builders, through training and inspection, to achieve and maintain satisfactory technical standards of home building.

Customer Service Centres To increase its visibility and serviced excellence to customers, the NHBRC established Customer Service Centres in all nine provinces. Activities range from registration of home builders, enrolment of new homes, inspec- tion of homes and handling of complaints, to conciliation of unresolved complaints.

Service points in municipalities are also being set up to establish and improve the accessi- bility of the NHBRC. Subsidy housing At the onset, the mandate of the NHBRC did not cover the low-cost housing (subsidy) sector. In February 2002, the Minister of Housing announced that the NHBRC Warranty Scheme will apply in the housing subsidy sector.

In the subsidy sector, the NHBRC has initiated remedial works of housing-subsidy failures. The organisation enrols new housing builds, conducts the geotechnical, civil and structural assessments required, inspects the builds and materials used and through its builder-training programmes empowers builders in respect of product and technical knowledge.

Home-builder registration Every home builder who is engaged in the process of building a home or selling a home should be registered with the NHBRC. Home builders undergo an assessment test to ensure that they meet the requirements. They are also

Alternative home building technologies The NHBRC has a vision to create a society living in secure, comfortable and decent homes.

The NHBRC has been advocating the use of alterna- tive technology in the home-building industry with the aim of providing quick to erect,

that they are included in the database of the NHBRC.

eradicating the housing backlog in the country.

The Eric Molobi Housing Innovation Hub was launched in 2007, with the objective of identifying and supporting innovative housing systems developed nationally and internationally and which would provide a wider choice of quality and

Home-building inspections Inspection services are provided to registered builders with enrolled projects/homes to assist them in building homes with structural integrity, resulting in low levels of housing consumer complaints.

Home-builder training and development The NHBRC provides training and skills development to builders to build skills capacity. This entails developing and managing systems and processes for the delivery of training and devel-

CONTACT DETAILS Tel: Toll-free number: 0800 200 824 (SA only) Physical address: 5 Leeuwkop road, Sunninghill, Sandton Johannesburg

www.nhbrc.org.za

OVERVIEW OF CERTIFICATION TRENDS FOR INNOVATIVE BUILDING TECHNOLOGIES (IBTS) IN SOUTH AFRICA C. Mphahlele and Dr. B Wekesa

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CERTIFICATION TRENDS GREEN STAR RATING TOOL

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he South African Government has undertaken to deliver 60% of social infrastructure such as schools, early childhood development centres, clinics and student accommodation with the use of Innovative Building Technologies (IBTs).

As a result of this resolution, it has become important that the IBT sector is understood, particularly the drivers and barriers that exist in the industry.

The study aims to analyse these issues so that those government departments involved in the implementation of this resolution can make informed decisions. The objective of the study is to provide insight on the trends in the IBT sector over the years. The trends pertain to certification by Agrément South Africa over five year periods and building system material composition and application methods.

IBTs are defined by the CSIR as any building method that offers an alternative solution to meeting the performance requirements of the National Building Regulations and Building Standards Act (103 of 1977). According to the National Building Regulations, building methods that are not covered in the regulations must be submitted to the authority approving building designs by way of rational design or Agrément certification.

Agrèment is a body mandated by the Department of Public Works to undertake certification of IBTs and other non-standard building products. Certification serves as assurance that building systems are fit-for-purpose.

For purposes of understanding how trends were identified, a brief overview of the problem that informed this study and the analysis process adopted in the study is provided. A discussion with respect to the results and recommendation for future research is also part of this study.

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CERTIFICATION TRENDS

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The Problem in Context The CSIR established the Advanced Construction Technology Platform (ACTP) in 2006 with the objective of encourage the uptake of science, technology and innovation in the construction industry. The ACTP supports government’s resolution to employ greater use of IBTs which has necessitated the need to understand the IBT industry. The environment in which IBT stakeholders conduct business is expected to have slight differences when compared with the environment in which conventional construction business activities take place. The envisioned differences revolve around issues such as the business models of the various certificate holders, the type of technology used, the skills requirement and potential for job creation. These differences are largely a result of the Agrément certification requirement. Certificates granted by Agrément not only prescribe the systems manufacture and application, but also the conditions under which the certificate will remain valid.

In order to evaluate the implications of the certification requirement on various IBT-based businesses the CSIR undertook a five-part “IBT baseline study”. This chapter is based on the second part of the study. The study aimed to identify certification trends with respect to the various certified building technologies listed on the Agrément database as active.

Analysis Process The identification of certification trends involved the analysis of 86 systems listed as active on the Agrément database. The analysis involved evaluation of the following certificate characteristics: The date of certification: This provided an overview of the number of certificates issued per five year interval.

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System Composition: This evaluation resulted in the systems being categorized into six categories as follows: Light Building System (LBS), steel structural frame: consists of a steel frame which is clad internally and externally with a waterproof building board. The cavity between the boards will have insulating material.

LBS, steel structural frame, insulated foundations: these systems are similar to type I system except the foundations are insulated.

Figure 1: Light Building System, Steel Structural frame (http://www.globalsystems.co.za/ content/projects/id/43) LBS, panels, light weight concrete: consist of panelised systems which are either interlocking or bolted together. The panels are connected by way of a ring beam or roof structure. The walls will be sealed with a flexible sealent.

Figure 2: Light Building System, Panels, Light Weight Concrete (www.tradenet.org)

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Save time, money and the environment with Hansgrohe’s range of EcoSmart taps and mixers.

With its reputation as a leader in sophisticated design and a champion of the value of water, Hansgrohe is pioneering the way in which consumers save water and contribute towards a sustainable society. Hansgrohe’s innovative range of EcoSmart taps and mixers is not only functional, intuitive and beautifully made, it’s also designed with a major emphasis on sustainability, with EcoSmart products requiring up to 60% less water than conventional bathroom fittings.

This means consumers can now enjoy a luxury bathroom experience while saving time, money and water.

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Cost efficient eco-construction ahead Prodigious Construction and Property Development Consultants is a medium sized quantity surveying firm based in Cape Town. The company is recognised for eco-friendly sustainability and their understanding of an urgent need to lower environmental impact. This has seen Prodigious integrating advanced technological energy saving solutions such as Photovoltaic (Solar PV) systems and Radiant heating solutions to their latest projects.

Radiant heating solutions can be used in all commercial and residential properties and, as such, has been included in all projects undertaken by Prodigious where possible. Different applications of the system which uses convection and radiation to exchange heat through temperature-controlled surfaces with their surrounding environment, are tailored to each project to ensure lowest energy consumption at all times.

In addition to installing Radiant heating and cooling systems, Beau Constantia Wine Farm as well as a private residence have implemented a usable solar power supply and energy saving solution by means of Photovoltaics This substantially decreases the client’s main grid electricity consumption and costs.

In addition, it safeguards against main grid power

failures. Solar panels are installed on the roof and provides the source to convert sunlight into electricity, which is then stored in a battery back-up. This ensures uninterrupted full back-up power for up to 6 hours.

The system is fully controlled by the user through online monitoring software.

The plans and construction of Pearl Valley Golf and Country Estate also include the use of a grey water recycling system, which markedly reduces water consumption. Due to the need for relatively high water use, the system not only has a positive impact on the environment but drastically reduces costs and protects the Estate from water restrictions imposed during very dry seasons.

Prodigious Construction and Property Development Consultants has accomplished experience and offers a comprehensive range of professional property consulting services. Their main aim is to provide costeffective and efficient turnkey quantity surveying services. Implementation of environmentally efficient systems in all their projects have earned them a good standing within the industry for providing cuttingedge, sustainable ecological solutions to new and existing urban developments and housing projects.

No 2 Redlands Road, Milnerton, Cape Town 7435 - South Africa Tel: +27 21 551 0171 • Fax: +27 21 551 9112 • Email: roelof@prodigious.co.za • www.prodigious.co.za

2

Hybrid Building Systems: These systems are a complex mix of concrete, insulating materials and structural frames.

Figure 3: Hybrid System (http://insulationlsa. weebly.com) Heavy Weight Building System (HWBS), panels, dense concrete: These systems are made up from dense concrete panels which are cast in-situ or prefabricated.

Figure 4: Heavy Weight Building System, panels, dense concrete (http://southwest.construction. com)

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GREEN STAR RATING TOOL CERTIFICATION TRENDS

Figure 5: Heavy Weight Building System, building Block (http://www.indiamart.com) The definitions for the various categories was provided by the CSIR. Evaluation of system composition also resulted in the identification of popular materials used in the IBT industry through the evaluation of the “general description” contained in the Agrèment certificate Application methods: This evaluation resulted in the categorization of building systems in categories such as In-situ, Off-site or Off-Site/In-Situ combination construction.

The categorization of building systems was based on the erection methods described in section three of all building systems.

Certification Trends Analysis of trends with respect to Agrément certified building systems database is illustrated in Figure 6. Percentages are a total of all active certificates. The results show a sharp increase in certifications after 2007. Figure 1 illustrates that 67% of all systems were certified during the 20082013 period. This could be an indication of the anticipated demand-pull phenomenon resulting from Government’s resolution of August 2013. Certificate holders might be anticipating the increase in demand as a result of government’s ambitions to use more IBTs on social infrastructure projects.

HWBS, Building Blocks: These systems consist of cast-in situ or prefabricated hollow or solid building blocks.

Figure 6: Certification Trends Material Composition and Erection Methods

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CERTIFICATION TRENDS GREEN STAR RATING TOOL

1

2

The material composition of the building system is detailed in the ‘Preamble’ of the certificate, usually in the form of a diagram illustrating a section in the certificate.

The diagram will clearly illustrate the composition of the building system. Part 1 of the certificate provides an outline of the conditions under which the certificate will remain valid.

Part 2 of the certificate gives an outline of the performance of the building system. This includes areas such as the system’s behaviour in fire, structural performance, water penetration, thermal performance, energy usage, condensation, acoustic performance, durability and quality management. Most of the criteria contained in Part 2 are evaluated in terms of the National Building Regulations and Standards Act, 1977. The performance of the system must be equivalent to or exceed the parameters of the regulations.

Part 3 of the certificate provides a general description of the system; this section also allows one to clearly evaluate the system’s material composition and how the materials are put together. The evaluation of these sections revealed that 79% of all certified systems are panelised system falling under the following categories: • HWBS, panels; • Hybrid Building Systems; • LBS, light weight concrete, panels; and • Light Building System (LBS), steel structural frame HWBS panels systems are not as popular as the other three categories of building systems. This trend is consistent with the finding reported by Arnold (2002), where he indicated a decline in active certificates for large precast panels’ type of systems.

Panelised systems falling under Hybrid and LBS categories are popular because they are simpler to manufacture and transport. Predominant materials used in the

IBT sector are also in line with the panelised systems trend. It was found that concrete and cement products were mostly used to make both HWBS and Hybrid System panels.

The panels come either in hollow and solid forms.

Polymers such as polyurethane, expanded polystyrene and polystyrene beaded concrete were mostly used as infill or cladding or as a shell for hollow panels in the four predominant categories. Polymers used in systems falling under popular categories have the added advantage of improving insulation and condensation properties of the building system. This in turn improves the energy and thermal performance.

Steel products are used mainly as frames to support the panels. These systems will then fall under the LBS, steel structural frame category. The least popular category is HWBS, building blocks.

The manufacture may be entirely factory based which falls under the “offsite production” category. One would expect that panels be entirely manufactured in a factory as this will reduce time spent on site and ensure greater accuracy therefore reducing wastages. However, it was found that the heavier panelised systems rely on a combination of total “in-situ” construction or a combination of “offsite production/ in-situ erection” because of the difficulty involved with the transportation of such systems.

All scenarios of erection have the benefit of equipping workers in the industry with better employment prospects either through the development of new skills or stable employment. In the case of offsite production, workers get the benefit of more permanent employment in factories.

Where in-situ erection is prescribed, the local community are able to acquire specialised skills.

BUILDING MATERIALS AND TECHNOLOGIES HANDBOOK 26 24THE GREEN THE GREEN BUILDING MATERIALS AND TECHNOLOGIES HANDBOOK

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Sustainability and Certified Systems IBTs also have the added benefits with respect to energy use and improving the general habitability of the building envelope. A study conducted by the CSIR in 2013 revealed that a building envelope constructed with the use of Agrément certified building systems perform better than the standard brick house in the areas of energy use, condensation, thermal performance, acoustics, durability and behaviour in fire. In fact, when comparing the performance of various building systems, a standard brick house was ranked 32 out of 44 building systems.

As part of the baseline study in 2014, systems that were not evaluated in the 2013 study were evaluated. It was found that systems are still outperforming the standard brick house, where words such as “better than” or “exceeding” the provisions in the regulations or a standard brick house can be found in the performance description. More than 50% of the building systems certified after the 2013 study perform better than a standard brick house in terms of energy and thermal performance. The condensation and acoustic properties of building systems are found to be similar to a standard brick house in all the systems.

The thermal, energy, condensation and acoustic properties of building systems support the creation of comfortable and efficient buildings.

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CERTIFICATION TRENDS GREEN STAR RATING TOOL

increased demand for their building systems in the construction industry. Active certificates on the Agrément data base show that there is a great variety in terms of application methods; this is encouraging as it shows that certificate holders are innovative.

It would be interesting to conduct a study where inactive certificates are evaluated.

The trends unveiled in such a study would give insight into the challenges being faced by certificate holders and Agrément SA in terms of growing the active certificates data base. Further to this, a study such as this will identify changes in the various categories as innovators develop new erection methods with the use of new polymers and cement products. Such a study will add to the knowledge base that has been created by (Arnold, 2002), who also undertook to analyse the use of Agrément certificates between the years 1993 and 2002.

1 Building Science and Technology, CSIR, Pretoria Telephone: 012 841 2546 Email: cmphahlele@csir.co.za 2 Agrément South Africa, CSIR, Pretoria Telephone: 012 841 2544 Email: bwekesa@csir.co.za

Discussion and recommendations for future research It is clear that there is an upward trend with respect to certification of new building systems. Certificate holders are anticipating References • •

Arnold, N., 2002. The Use of Agrement South Africa Certicates Between 1993 and 2002, Pretoria: Not Published.

CSIR, 2013. Innovative Building Technlogies: The Value Proposition, Pretoria: CSIR.

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CRADLE-TO-GATE LIFE CYCLE GREENHOUSE GAS EMISSIONS OF SOUTH AFRICAN MAJOR BUILDING MATERIALS Nozonke Dumani

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he consumption of energy in the world contributes to a range of environmental problems, including greenhouse (GHG) emissions, ozone layer depletion, eutrophication and acid deposition (Asif, Muneer and Kelley, 2007). The building sector (residential and commercial) contributes the most to the energy consumption thus making a significant contribution to GHG emissions (Pargana, Pinheiro, Silvestre and de Brito, 2014). It is responsible for 40-50% of the overall energy consumption in the world (Dixit, Fernandez-Solis, Lavy and Culp, 2012; Gursel, Masanet, Horvath and Stadel, 2014).

Furthermore, the building industry is, after the food industry, the greatest consumer of raw materials and accounts for 40-50% of all raw materials extracted from the Earth’s crust annually (Koroneos and Dompros, 2007; Dimoudi and Tompa, 2008; Bribian, Capilla and Uson, 2011). Each building material consumes energy and releases GHG emissions during its production.

The building entire life cycle is divided into three phases, namely, the pre-use phase, the use phase and post-use phase (Huberman and Pearlmutter, 2008). The

CRADLE-TO-GATE LIFE CYCLE

pre-use phase is dominated by material processes from raw materials extraction through building material manufacturing to on-site construction all of which contribute to the initial embodied energy and typically accounts for only about 10-15% of the total life cycle building energy. The use phase contributes to operational energy use (lighting, heating, ventilation and use of appliances) and recurring embodied energy (maintenance, repair or replacement of materials) and accounts for 80-90% of total life cycle. The post-use phase refers to the end-of-life (EOL) options for materials disposal which includes materials recovery (reuse or recycling) and/or landfill and accounts for less than 1% of total life cycle (see Figure 1).

Until recently, most efforts have been made to reduce the operational energy use of the building owing to its large contribution to the total life cycle energy.

Numerous measures have been undertaken such as better building designs, and the use of advanced and effective materials to reduce the energy needed for the operation of buildings (Thormark, 2002; Dixit, Fernandez-Solis, Lavy and Culp, 2010).

Figure 1: The building life cycle stages THE GREEN BUILDING MATERIALS AND TECHNOLOGIES HANDBOOK

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This has resulted in more energy efficient buildings. However, according to Bribian et al. (2011) in low-energy buildings, the embodied energy of building materials can account for as much as 9-46% of the total life cycle energy. Therefore, from an energy use perspective, the relative importance of the building life cycle stages is changing, as the GHG emissions associated with the embodied energy of materials gains in importance.

In South Africa, 28% of total national GHG emissions are attributed to the building sector with operational energy of the residential and commercial sectors accounting for 23% while the manufacturing energy of selected major building materials accounts for 5% (CIDB, 2009). South Africa, like the rest of the world, is currently focused on reducing the GHG emissions associated with the operation of buildings. However, now that embodied energy is starting to play a significant role in the total life cycle energy of buildings, more research needs to be undertaken to better understand the building materials contribution to the life cycle GHG emissions of building in South Africa.

This chapter aims to evaluate how the major building materials contribute to the life cycle GHG emissions of the South African building sector. This study will analyze the environmental hotspots in the life cycle of each building material as well as identify improvement options of each material from an environmental perspective. The studied materials include cement, aggregates, reinforcing steel, masonry concrete block, concrete roof tiles, and glass wool insulation.

Building materials The environmental sustainability of building materials is of importance. The choice of building materials determines the energy required for the construction of buildings as well as environmental implications (Dimoudi and Tompa, 2008).

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Most conventional materials used in modern buildings (such as concrete, reinforcing steel, brick, ceramic tiles etc.) are energy intensive and associated with high environmental emissions (Dimoudi and Tompa, 2008). It is therefore important to evaluate the environmental impacts associated with conventional South African building materials.

Cement Cement, the binding agent in concrete, is considered one of the most important and most produced building materials around the world. It comprises about 10 to 15% of the volume of concrete (Muigai, Alexander and Moyo, 2013). In 2013 the estimated production of cement in South Africa was about 13 million tonnes and 55% of the total was used in the building industry (LHA Management Consultant, 2014).

Cement production is one of the largest contributors to global warming, accounting for approximately 5-7% of global GHG emissions (Humphreys and Mahasenan, 2002). Cement production is a highly energy intensive process. Clinker production is the most energy intensive stage in the production of cement. It accounts for over 90% of the total energy use and related GHG emissions (Worrell, Martin and Price, 2000). The most common form of cement is Ordinary Portland cement (OPC) which has approximately 95100% clinker content (Josa, Aguado, Heion, Byars and Cardim, 2004). Studies have been done to evaluate the environmental impact of cement. Flower and Sanjayan (2007) completed a study to quantify the greenhouse gas emissions associated with the manufacture of concrete. The results showed that the ordinary OPC generated the major greenhouse gas emissions and was due primary to the clinker process stage.

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Aggregates Aggregate is a structural filler in concrete and account for 65% to 80% of the volume of concrete (Muigai et al., 2013). Aggregate includes gravel, sand, crushed stone and recycled aggregate. Crushed stone is usually designated as coarse aggregate and sand as fine aggregate. Aggregate production is less energy intensive and thus results to less GHG emissions. The small amounts of GHG emissions mainly arise from electricity for the crushing process (Flower and Sanjayan, 2007).

Reinforcing steel Reinforcing is an essential component in reinforced concrete and is added to improve the strength of concrete (Gonzalez, Andrade, Alonso and Feliu, 1995). Steel is commonly used as reinforcement in concrete slabs, beams and columns (Vares and Hakkinen, 1998). Steel rebar is the most common reinforcing material used in South African concrete.

Steel production is a highly energyintensive production process and results in very large amounts of GHG emissions.

Globally, the greenhouse gas emissions associated with steel production is approximately 1.52 t CO2eq (Wright, 2011).

As compared to this, steel produced in South African results in higher GHG emissions of approximately 2.98 t CO2e per ton of liquid steel. This is attributed to South African steel produced primarily from virgin steel (ArcelorMittal, 2013).

Concrete block Concrete block accounts for about 79% by mass of the total market for walling, masonry in South Africa 2013 (LHA Management Consultants, 2014). It has taken the market share from clay bricks. This is attributed largely to the high cost required in tunnel kilns when manufacturing clay bricks (CIDB, 2007). Concrete blocks can be solid or

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hollow. Hollow concrete blocks held the major share at about 74 % by mass in 2013 (LHA Management Consultants, 2014).

The concrete commonly used to make concrete blocks is a mixture of OPC, water, sand, crushed stone (BMTPC, 2002). Ordinary Portland cement, sand, crushed stone generates the majority of GHG emissions during the production of hollow concrete blocks.

Concrete roof tiles The roofing market in South Africa consists predominately of steel roofing material, concrete tiles, fibre cement, clay tiles natural slate tiles (CIDB, 2007). Steel held the major market share at about 57% followed by concrete tiles at about 24% share by volume (CIDB, 2007).

The basic raw materials used in the manufacture of concrete roof tiles are ordinary Portland cement (OPC), sand, water and inorganic pigments. Concrete tiles are made from roughly 75% sand, 20% OPC with the rest consisting of water and inorganic pigments. The mixture is usually extruded in individual moulds to form the tile.

Studies have been done to investigate the environmental impacts of concrete tiles.

Szakaly, Spangberg, Hagstrom, Englund, Fritzell, Akesson, Johansson, Andersson (2001) did a cradle-to-gate comparative life cycle assessment study to compare concrete roof tile to a painted steel roof covering. The findings show that the concrete roof tile contributes the least to the environmental effect as compared to the steel roof sheet.

This is attributed to that the extraction of sand which is the largest part of concrete roof tile is not very energy demanding whereas the mining of iron ore and steel production are.

Glass wool insulation The insulation market in South Africa consists of glass wool, rig boards, polyester fiber, and

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cellulose fiber. The major market share is held by glass wool at about 67 %, followed by rigid boards at about 19% by mass, the rest is held by polyester and cellulose fiber (LHA Management Consultants, 2014).

Glass wool is made from molten sand and cullet (recycled glass). Generally, 30-60% of the raw material input is usually the recycled fraction. Typically to lower the melting temperature soda ash and limestone are used. Phenol formaldehyde based resin is generally used as a binding agent to prevent the material from sagging during use (Murphy and Norton, 2008). Glass wool production is a highly energy-intensive process. This is attributed to the fact that the raw materials (sand and cullet) have to be melted to generally high temperatures (1500-1550C) in an electric furnace.

Research methodology A Life Cycle Assessment (LCA) was performed in order to achieve the purpose of the study. LCA is a method for evaluating the environmental impacts associated with a product by quantifying the resources consumed (energy, materials, water, and land) and the emissions to the environment (air, water and soil) at all stages of the product life cycle. It considers environmental impacts from all life cycle stages starting from raw material extraction to manufacturing, use and maintenance and disposal. According to the international standards ISO/SANS 14040:2006 and ISO 14044: 2006, an LCA study entails four mandatory steps, namely: • Goal and scope definition which states the objective of the study; and defines the system boundaries and unit of analysis; • Life cycle inventory (LCI) analysis which involves data collection and calculation of an inventory of materials, energy and emissions related to the system being studied;

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• Life cycle impact assessment (LCIA) which involves analysis of the LCI results to evaluate contributions to environmental impact categories; and • Life cycle interpretation which entails evaluation of the LCI and LCIA results in consideration of the goal and scope in order to reach conclusions and make recommendations.

Goal and scope definition Goal The objective of the study is to quantify the life cycle greenhouse gas emissions associated with conventional South African building materials. The secondary objective is to analyse the environmental hotspots in the life cycle of each material and identify viable improvement options on the predicted performance of each material.

Scope The scope of the LCA study, as shown in Figure 1, is limited to a cradle-to-gate analysis. The impact category considered in this study is climate change, that is, GHG emissions. The functional unit of analysis for all the conventional building materials is one kilogram (kg) of material.

Life cycle inventory The LCA software tool SimaPro 8.1 was used to compile cradle-to-gate life cycle GHG inventories for conventional building materials. As it was difficult to obtain South Africa-specific LCI data, European industry average data obtained from the ecoinvent Database version 3 were ‘localised’ and used in this study. The datasets were ‘localised’ by changing the electricity mix for all selected datasets to the South African county mix. SimaPro offers a range of LCIA methods to choose from and the ReCiPe midpoint (H) method was chosen in this study.

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Results and discussion The CO2 equivalent emissions of conventional building materials are presented in Table 1 Cement The clinker production stage is the environmental ‘hotspot” in the production of cement accounting for approximately 95% of the total GHG emissions of cement production The clinker production is the most energyintensive stage in the production of cement and has significant environmental impact. In order to reduce the GHG emissions released during OPC production the clinker content of OPC could be partially replaced with less energy intensive supplementary cementitious materials (SCMs) (Flower and Sanjayan, 2007).

Alternative fuels could also be used to replace fossil fuels (Bribian et al., 2011).

Aggregates The GHG emissions due to the production of coarse and fine aggregates are depicted graphically in Figures 3-4. The environmental ‘hotspot’ for both coarse and fine aggregates is the electricity consumption accounting for approximately 74% and 58% respectively.

The electricity is used during the crushing process to run electric crushing equipment during the production of coarse aggregate whereas electricity is consumed by the pumping and grading equipment during the fine aggregate production. In order to lower electricity demands, the rocks should be blasted into smaller fragments using explosives during extraction process prior to crushing and quality of the equipment used needs to be investigated (Flower and Sanjayan, 2007).

Reinforcing steel The pig iron production stage is the ‘hotspot’ accounting for approximately 80% of the

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total GHG emissions of reinforcing steel.

These emissions resulted mainly from coal used to fire the blast furnace and coke making. In order to reduce the GHG emissions released during the production of steel, scrap steel instead of virgin steel should be used in South Africa and alternative fuels should be used as well to fire the blast furnace.

Concrete block The main greenhouse gas emissions contributor is the OPC production process in concrete block production. The OPC contributes approximately 77% to the total GHG emissions. As mentioned, the clinker production is the most energy intensive stage in the production of OPC. Therefore the clinker content in OPC should be replaced with clinker substitutes (fly ash and GGBFS) to reduce the GHG emissions released during concrete block production.

Concrete roof tiles The hotspot in the concrete roof tiles production is the OPC production which accounts for about 74% of the total GHG emissions. Therefore, reduction of the environmental impact of concrete roof tiles should focus on OPC production process. In order to reduce the GHG emissions released during OPC production, alternative fuels should be used and clinker content of OPC should be partially replaced with SCMs. Glass wool insulation Glass wool production is an energy-intensive process. The majority of GHG emissions resulted from the consumption of electricity, being responsible for about 72% of total GHG emissions. This is attributed to the fact that the materials have to be melted at high temperatures in an electric furnace.

The CO2 equivalent emissions of the conventional materials are shown in Table 1.

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Material

kgCO2eq/kg

Ordinary Portland Cement

0.973

Coarse aggregate

0.0136

Fine aggregate

0.00514

Reinforcing steel

2.23

Concrete block, hollow

0.102

Concrete roof tiles

0.271

Glass wool insulation

3.5

Table 1: Results for conventional building materials Conclusions The primary purpose of this study was to quantity the GHG emissions associated with conventional South African building materials. The secondary aim was to identify potential environmental ‘hotspots’ and suggest improvement options to be implemented on each material. LCA methodology was applied to quantify GHG emissions during cradle-to-gate production of conventional building materials.

The results suggest that the largest contribution to the GHG emissions of OPC, concrete block and concrete roof tiles originates from the clinker production process. Therefore to reduce this, the focus has to be on replacing the clinker content in OPC with SCMs. The results also suggest that

the major contributor to GHG emissions of aggregate and glass wool insulation is the electricity consumption. In order to reduce this, explosives should be used to blast rocks prior crushing during coarse aggregate extraction and efficient equipment should be used. It was shown that the reinforcing steel contributes significantly to the GHG emissions associated with conventional building materials in South Africa. In order to reduce the GHG emissions associated with steel production, it was suggested that alternative fuels should be used to fire the blast furnace and steel should be produced from scrap instead of virgin raw materials. It can be observed from the results that major building materials contribute significantly to the life cycle GHG emissions of buildings.

References

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ArcelorMittal South Africa, 2013. Towards recovery – Sustainability report Asif, M., Muneer, T., and Kelley, R., 2007. “Life cycle assessment: A study of a dwelling home in Scotland.” Building and Environment 42, 1391-1394 BMTPC (Building Materials & Technology Promotion Council), 2002. Techno economic feasibility report on concrete hollow and solid block, Ministry of Housing & Urban Poverty Alleviation Government of India, New Delhi Bribian, I.Z., Capilla, A.V., and Uson, A.A., 2011. “Life cycle assessment of building materials: comparative analysis of energy and environmental impacts and evaluation of the eco-efficiency improvement potential.” Building and Environment 46, 1133-1140 CIDB, 2007. The building and construction materials sector, challenges and opportunities. Pretoria: Construction Industry development Board

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CIDB, 2009. Greenhouse Gas Emission Baselines and Reduction Potentials from Buildings in South Africa. Pretoria: Construction Industry Development Board Dimoudi, A., and Tompa, C., 2008. “Energy and environmental indicators related to construction of office buildings.”

Resources, Conservation and Recycling 53, 86-95 Dixit, M.K., Fernandez-Solis, J.L., Lavy, S., and Culp, C.H., 2012. “Need for an embodied energy measurement protocol for buildings: A review paper.” Renewable and Sustainable Energy Reviews 16, 3730-3743 Dixit, M.K., Fernandez-Solis, J.L., Lavy, S., and Culp, C.H., 2010. “Identification of parameters for embodied energy measurement: A literature review.” Energy and Buildings 42, 1238-1247 Flower, D.J.M., and Sanjayan, J.G., 2007. “Greenhouse gas emissions due to concrete manufacture.” International Journal of Life Cycle Assessment 12(5), 282-288 González, J. A., Andrade, C., Alonso, C. and Feliu, S., 1995. “Comparison of rates of general corrosion and maximum pitting penetration on concrete embedded steel reinforcement.” Cement and Concrete Research 25, 257-264 Gursel, A.P., Masanet, E., Horvath, A., Stadel, A., 2014. “Life cycle inventory analysis of concrete production: A critical review.” Cement and Concrete Composites 51, 38-48 Huberman, N. and Pearlmutter, D., 2008. “A life cycle energy analysis of building materials in the Negev desert.” Energy and Buildings 40, 837-848 Humphreys, K., and Mahasenan, M., 2002. Toward a Sustainable Cement Industry – Substudy 8: Climate Change.

Battelle – World Business Council for Sustainable Development.

Josa, A., Aguado, A., Heion, A., Byars, E., and Cardim, A., 2004. “Comparative analysis of available life cycle inventories cement in the EU.” Cement and Concrete Research 34, 1313-1320 Koroneos, C. and Dompros, A., 2007. “Environmental assessment of brick production in Greece.” Building and Environment 42, 2114-2123 LHA Management Consultants report, 2014. Building industry statistics. - Pretoria: LHA Management Consultants.

Muigai, R., Alexander, M.G., and Moyo, P., 2013. “Cradle-to-gate environmental impacts of the concrete industry in South Africa.” Journal of the South African Institution of Civil Engineering, 55(2), 2-7 Murphy, R.J., and Norton, A., 2008. Life cycle assessments of natural fibre insulation materials, London: NNFCC Pargana N, Pinheiro, M., Silvestre, J.D., and de Brito, J., 2014. “Comparative environmental life cycle assessment of thermal insulation materials of buildings.” Energy and Buildings 82, 466-481 Szakaly, A., Spangberg, F., Hagstrom, P., Englund, C., Fritzell, J., Akesson, M., Johansson, K-G., Andersson, A., 2001, Life cycle assessment of paint sheet vs. concrete roof tile. [Online] Available from: http://citeseerx.ist.psu.edu/viewdoc/ download?doi=10.1.1.195.2915&rep=rep1&type=pdf, [accessed: 23 March 2015].

Thormark, C., 2007, Energy and resources, material choice and recycling potential in low energy buildings. In: CIB Conference , SB07 Sustainable Construction, Materials and Practices Vares, S., Häkkinen, T., 1998. Environmental burdens of concrete and concrete products. Technical Research Centre of Finland, VTT Building Technology. [Online] Available from: http://www.betong.net/ikbViewer/Content/739021/doc21-10.pdf, [Accessed: 23 July 2014].

Worrell, E., Martin, N., and Price, L., 2000. “Potentials for energy efficiency improvement in the US cement industry.”

Energy 25, 1189-1214 Wright, M.A, 2011. “Carbon dioxide equivalent emissions from the manufacture of concrete in South Africa”. MSc thesis, University of Witwatersrand, Johannesburg

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Human settlements historically conjure up contradictory images (think Charles Dickens’s A Tale of Two Cities): one is that of the dynamic, cosmopolitan centre of business, culture and entertainment with lively, diverse and socially inclusive neighbourhoods, home to many millions of people. The other image is more ominous: dilapidation, degradation, crime, dangerous streets, poverty, pollution, and social exclusion, again ‘home’ for many millions.

Both images are partial reflections of South Africa’s human settlements: “coming to terms with our cities [and settlements] in all their complexity is a key challenge for the development of effective public policy” aimed at advancing sustainable human settlements (Policy Research Initiative 2002:1).

Increasingly calls are made for science to be integrated into policy development under the banner of ‘science for policy’ or ‘evidence-based policy’ (EBP) although it is argued that the importance of understanding and using science for public policy-making has long been recognised (as in the Rothschild Report of 1971) and that relevant policies should take into account both scientific knowledge and the needs of science (Head 2009:17). Sutherland, Bellingan, Bellingham, Blackstock, Bloomfield, et al (2012) argue that EBP has become the norm in many fields and that many governments engage scientists at a senior level. Advocates of EBP suggest that EBP was first suggested in the UK in the 1999 White Paper on Modernising Government where it states “This Government expects more of policy makers. More new ideas, more willingness to question inherited ways of doing things, better use of evidence and research in policy making and better focus on policies that will deliver long term goals”.

The ESRC also notes that there is a renewed focus in commissioning research that assists

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not only in understanding a problem but offers some guidance to make it better (ESRC 2001:4; Head 2009:16).

More recently members of the Scientific Advisory Board of the UN SecretaryGeneral stressed that “science is the key to a sustainable future” and that the “interface between science and policy must be improved in order to develop and implement these solutions effectively” (UNESCO 2015).

Background Agenda 21 formed the basis of the comprehensive programme for action agreed to by delegates from most of the countries of the world at the United Nations Conference on Environment and Development (the Earth Summit) that took place in Rio de Janeiro in 1992. It provided a blueprint for action in all areas relating to sustainable development of the planet. Agenda 21 called for changes in the economic development activities of human beings – changes that are based on a new understanding of the impact of human behaviour on the environment. The call for sustainable development is not simply a call for environmental protection, but is in fact a call for a new concept of economic growth – one that provides fairness and opportunity for the entire world’s people, without further destroying the world’s scarce natural resources and carrying capacity. Sustainable development thus addresses economics, finance, trade, energy, agriculture, industry and all other policies to bring about development that is economically, socially and environmentally sustainable.

Chapter Four of Agenda 21 specifically focuses on changing consumption patterns by promoting patterns of consumption and production that reduce environmental stress and developing a better understanding of the role of consumption, and how to bring

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about more sustainable consumption patterns while Chapter Seven of Agenda 21 specifically focuses on promoting sustainable human settlement development and was one of the first global agreements that included “scientific and technological means” as a means of implementation (UNCSD 1992).

Science, technology and innovation The march of technology, while significant globally, has been uneven sectorally. The change in information processing and health care has been far more rapid than in energy, transportation, and manufacturing for example, (let alone construction). In 1973, before the energy crisis of the later 1970s, fossil fuels such as natural gas, gasoline, and coal accounted for 86,7 percent of global energy consumed: in 2012, some 39 years later, those “old” technology fuels still provided 81,7 percent of global energy (IEA, 2014).

However, the enabling environment globally is more supportive now than it has been for a long time: science is advancing rapidly across a much wider front, more countries are willing to commit resources to research and development and education, and corporate managers are realising the benefits to be obtained from embracing technology change.

Private and government spending on R&D in the industrial countries has risen from 1.6 percent of gross domestic product in 1981 to 2.5 percent in 2014 in some cases (Unesco 2014) while published scientific research is still increasing with “no indications that the growth rate has decreased in the last 50 years” (Larsen and von Ins 2010). In addition, governments in Europe, the U.S. and Asia are increasing budgets for higher education, which produces a key input for innovation – educated workers.

It will be difficult to solve the most pressing long-term problems facing

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this century without technological breakthroughs. Meeting the energy demands of growing economies such as India and China will not be possible in the long term without new sources of energy. In this sense, the rate and path of innovation is more critical for determining the world’s economic growth than having a high rate of capital investment. Nor will it be possible to generate enough good jobs in the future without new innovative industries.

Ultimately innovation is about continually pushing back the boundaries of what is possible.

In this regard, the potential of science and technology for tackling poverty is much more than governments generally realise since scientific and technical capabilities determine the ability to provide clean water, good health care, adequate infrastructure and safe food. For example, governments and international organisations have far more economic advisers than policy advisers on science, technology and innovation. Yet, information and communications technology, biotechnology, nanotechnology, and new materials are vital for long-term economic transformation in developing countries, as demonstrated in the economic growth in much of south-east Asia and the Asian Pacific.

However, there are encouraging signs that science and technology are returning to the global and local development agenda, spurred on most recently by the tsunami disaster in the Indian Ocean. The growth of science and technology in fields such as seismic detection, hydrological dynamics and telecommunications offers significant opportunities to prevent the loss of life occurring on the scale that it did.

The science community’s ability to generate protective strategies and guide effected communities to reconstruct in a sustainable

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manner will increase as the understanding of earths systems by the science community deepens.

A report for the UN Secretary-General on how to radically reduce poverty and hunger within 10 years (UN, 2005) noted “Developed countries should reflect on the price of investing in building the capacity of developing countries to prevent or reduce the impacts of natural disasters, compared to the huge costs of international aid after the disasters have occurred”. The report singles out Africa for not appreciating the potential of science, technology and innovation for helping to solve poverty and hunger. However, to harness this potential, every effort must be made to ensure that scarce scientific and technology skills are not lost to the continent.

In the past the focus of aid policy was alleviating poverty directly, but recent initiatives from political institutions such as the United Nations and the World Bank indicate that science and technology could become fully integrated into policies at all levels by building local capacity and by ensuring that such capacity is integrated into initiatives designed to boost overall systems of social and economic innovation (Dickson, 2005).

The new growth model consists of a number of components including service delivery, new solutions based on process changes, component integration, transaction integration, value-added outsourcing, new infrastructure, and new information to help customers improve their returns and reduce their risk levels of their business. One of the first steps for R&D is to map and anticipate the next-generation needs of the market.

The development trajectory of enterprises has been, is and will continue to be influenced by the social effects of urbanisation and its alter ego, globalisation.

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The concentration of a large population in a small area maximises the competition for space and for comparative advantage, and thus forces a striving for specialisation (Davis, 1966). Urbanised populations, finding that they could no longer support themselves by agriculture, turn to manufacturing and trade, which flourish on specialisation. With the emerging changes to manufacturing within the smart growth context, critical research must be done into enabling those participants to remain engaged in a new, green urban economy.

There are encouraging signs that science and technology is returning to the local development agenda: the South African government has indicated a commitment to increase spending on scientific research and development from the current level of 0.81 percent of GDP to 15 percent of GDP by 2019 (South Africa Info 2014).

In response to the need to reconstruct South Africa’s research and development (R&D) capability, the Department of Science and Technology (formerly Arts, Culture, Science and Technology), produced a National R&D Strategy that is indicator based and rests on three pillars: innovation; science, engineering and technology (SET) human resource and transformation; and creating an effective government S&T system (DST 2002).

The ‘innovation’ pillar involves the establishment and funding of a range of technology missions that are deemed critical to promote economic and social development. These include two contemporary technology platforms, namely biotechnology and information technology.

Two additional missions are technology for manufacturing and technology to leverage knowledge and technology from, and add value to, our natural resources sector (DST 2002). In addition, a mission, technology for poverty reduction, will also be introduced.

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These missions will need to be managed in a coherent and integrated manner requiring strategic and operational functions to manage and resource technological innovation. It is envisaged that a dedicated institution, the Foundation of Technological Innovation, may be constituted to operate as a knowledge-based financing agency concentrating on innovation within each of the technology missions. The Foundation is expected to fund innovation across the public and private sectors, and across the value chain from concept to market with a key focus on high-cost development and market acceptance stages through commercialisation, incubation and diffusion.

The ‘human resource’ pillar is rooted in the need to increase the number of men and women from previously disadvantaged communities entering the sciences and remaining there, and a strategy to maximise the pursuit of excellence in global terms.

Young people will only be attracted to futures in R&D if it offers fulfilling and remunerative careers: for this reason the human resource pillar and the innovation pillar are inextricably linked. This will require, inter alia, a focus on the areas of South Africa’s strength, areas that include astronomy, human palaeontology and indigenous knowledge.

The ‘institutional’ pillar will address the issues of creating a clear distinction between the roles of line departments that deliver to specific sectors, and the DST; and ensuring that international best practice with respect to government funding of science and technology, namely the well-articulated functions of basic research (knowledge generation), innovation (new businesses, products and services), and venture capital, is observed.

In addition, the White Paper on Science and Technology (DACST1996) set the stage for the processes to be implemented in its

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mission to realise the potential of science and technology, particularly with regard to triggering sustainable socio-economic development and nurturing a climate of innovation. To support this aim, the Innovation Fund has been established to promote large-scale projects that focus attention on the main themes of government, namely competitiveness, quality of life, environmental sustainability and the harnessing of information technology to address the needs of society and the economy. The Innovation Fund was established in recognition that innovation, which is one the agents driving technological change, is primary to economic growth.

The Department of Science and Technology has identified 12 sectors that it believes technologies will be important to over the next 10 to 15 years. Regrettably, construction is not one of them.

The department undertook a Foresight Study (DST 2000) to establish the factors facing the science and technology system in South Africa. The study suggested that agrarian and industrial economies were saturated, and that the next 10 to 20 years would be dominated by huge growth in the information and digital economies.

It suggested that one could expect the emergence of a bio-economy driven by development in biotechnology and the combination of biotechnology and information technology (bioinformatics).

The challenge for South Africa is to deal with a declining industrial economy: Foresight Studies will have to be used to identify priorities for publicly funded research; encourage greater research and development investment in industry; improve technology awareness and uptake in small, medium and micro enterprises (SMMEs); and identify skills shortages in science and technology and action initiatives thereof.

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As part of the implementation of the recommendations of the Foresight exercise, government tasked the department to draft a National Biotechnology Strategy (NBS) with the aim of realising the potential for biotechnology to contribute to the economic development of South Africa.

In response to the increasing rates of knowledge production, dissemination and application, the shortening of product life cycles and the increasing competition for human resources, many countries are increasing their national investment in R&D. South Africa’s current level of 0.7 percent is significantly lower than it should be to ensure national competitiveness.

Accordingly, the National R&D Strategy envisages doubling government investment in science and technology over the next three years, with more gradual increases thereafter.

This would raise the national investment to over 1 percent which, not matching many of South Africa’s competitors, will signal an appropriate, comprehensive and sustainable strategy for the knowledge economy, South Africa’s current research community, and the new generation that will be required to achieve the national goals.

Lean manufacturing The concept of ‘lean’ manufacturing has arisen in many sectors of the U.S. economy as a direct attempt to improve the input to output relationship. In its most basic form, lean manufacturing is about the systematic elimination of waste where waste is viewed as any use or loss of resource that does not lead directly to creating the product or service a customer wants. It seeks to improve product quality, reduce production costs, enable the producer to be ‘first to market’ and be able to respond to customer needs quickly.

Lean manufacturing has of late given rise to a new field of study known as Industrial Ecology: industrial ecology examines local,

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regional, and global uses and flows of materials and energy products, processes, industrial sectors and economies. It focuses on the potential role of industry in reducing environmental burdens throughout the product life cycle and encompasses: • Material and energy flow studies otherwise known as ‘industrial metabolism’; • Dematerialisation and decarbonisation; • Technological change and the environment; • Life-cycle planning, design, and assessment; • Design for the environment; • Extended producer responsibility or product stewardship; • Eco-industrial parks or industrial symbiosis; • Product-oriented environmental policy; and • Eco-efficiency.

The principles of ‘lean’ manufacturing focus on creating a culture of continual improvement that engages employees to reduce the intensity of time, materials, and capital necessary to get into the market.

The employment of lean manufacturing principles has the happy consequence of resulting in improved environmental performance due to the systematic elimination of non-value added activity and waste from the production process. An EPA study (2003) found that non-value added activity can comprise more than 90 percent of a factory’s total activity.

Companies that choose to engage in lean manufacturing do so for three primary reasons: • To reduce production resource requirements and costs; • To increase customer responsiveness; and • To improve product quality.

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Unlike the Industrial Revolution where manufacturing was based on a ‘cradle to grave’ model of extracting natural resources for products destined for landfill sites, the post-modern manufacturing trend is a ‘cradle to cradle’ model in which products, like natural systems, constantly recycle themselves. Shifting attitudes on this issue requires a paradigm shift capable of overcoming established practices, effecting change, and implementing analytical methodologies that capture and value the full spectrum of costs and benefits. Four steps are required to achieve this: Understand the drivers. Companies and CEOs who understand what is driving directives such as those issued by the EU would have seen them coming. Crucially, from a foresight position, these directives are predictable, not random, and are embedded as a permanent feature of the post-modern economic landscape. Successful companies will be those who have aligned their future design trajectory with the future regulatory trajectory, eliminating a random factor in their product development cycle, and shifting their budget from attorneys to engineers and marketers (Friend, 2005); Drop the assumptions and face the facts. The misplaced belief that better environmental performance reduces financial performance rather than improving it is based on habit, not evidence. While attempting to green an existing product will cost more, integrating green into the design process will be more profitable, and satisfy stakeholder expectations (Friend 2005); Design what works – before it is demanded. The demand for green integration will happen inevitably: the question is when, not if. Some companies will take the initiative, follow the guidance of 3.8 billion years of nature’s R&D, and design products and processes that are both compatible with the inescapable

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requirements of living systems – and are profitable (Friend 2005); and Steer by the logic, not the thresholds.

Environmental regulatory policy has thus far focused on a political and scientific process of establishing acceptable thresholds that usually prove to be a compromise, causing uncertainty, and resulting in litigation. The biological design logic provides a simpler, clearer and more predictable decision path – and makes compelling business sense. Protagonists use the terminology of “regulatory insulation” as compared to “regulatory guesswork” to posit a business strategy based on a lean manufacturing that effectively insulates the company from future regulatory shocks (Friend 2005).

The new technologies The key to understanding the 21st century is that the rate of technological change will be twice as fast as that of the 20th century (Futurecast 2001). A substantial body of experts believe that nanotechnology, artificial intelligence, bioengineering and other ‘new’ technologies will revolutionise life during the 21st century (Futurecast 2001). However, contrary to those who believe these technologies will usher in a new economic order, the basic principles of economics will most probably remain intact throughout the 21st century (Futurecast 2001).

Advances in productive technology throughout the past two centuries have repeatedly caused pessimists to believe that machines will destroy more jobs than they create. Paul Samuelson’s widely used economics textbook Economics first printed in 1948, suggested that computers would lead to automation and destroy jobs. On the contrary, computers have proved to be one of the greatest job creating inventions of all time – and for the entire world. In reality, advances in technological efficiency always enable a market economy to do more

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than it could do before. People working in systems of economic freedom are able to take full advantage of the technological advances, and avoid the problems of rapid economic obsolescence that accompany it. Technological advances will require, as it did during the Industrial Revolution, increasingly massive investments to finance the accelerating technological changes – to build, maintain, and constantly improve the new technological facilities – and great entrepreneurial talent to develop new industries. Consequently, one can expect the new technologies to unleash unprecedented job creation.

Nanotechnology, for example, offers the greatest potential to reduce waste: as nanotechnology relies on constructing products molecule by molecule, the product does without the drilling, sawing, etching, milling and other fabrication methods that create waste along the production process.

In addition, the product can be produced in a manner that facilitates its deconstruction at the end of its lifecycle and reconstitution into a new product. The embedding of nanotechnology holds promise of stimulating a new societal ethos, that of dematerialisation. As society realises that it can enjoy its traditional pleasures without consuming materials and generating waste (downloading music direct to the hard drive instead of consuming materials required to make and package cd’s), society’s view of what enhances quality of life will change. Huge strides will be made in nanotechnology resulting in amazing capabilities: however, the creation, maintenance, and constant improvement of nanotechnology facilities and components will remain immensely expensive for some time to come. Nanotechnology is therefore likely to supplement rather than replace traditional manufacturing for the foreseeable future. It will certainly not eliminate labour.

SCIENCE, TECHNOLOGY INNOVATION GREENAND HVAC SYSTEMS

New and smart materials, the result of the development of materials science, are being invented that can swell and flex, repel paint, repair itself, adapt to the environment and capture and store the energy of the sun.

Structures built from new materials have the ability to provide information to their occupants and be more environmentally sustainable. However, understanding and maximising the benefits of these new materials will require multi-disciplinary skills.

Biomimetics, on the other hand, studies the way nature addresses problems, such as the adhesive capability of a mussel. Using biomimetics may lead to new adhesives that enable buildings to be glued together, instead of relying on the variable adhesive qualities of mortar. This technology requires the collaborative knowledge of biologists, physicists, chemists and engineers working in integrated teams.

Embedded systems are essentially computers that form an integral part of equipment, machinery or plant. They classically include microprocessors that can read and convey information to a central processing unit or user. As such, they can alert a user to imminent failure or take corrective action, as in the case of ABS brakes on a modern vehicle.

Construction technology agenda Given the above, the five phase approach adopted by Daimler-Chrysler offers useful waypoints for the construction sector. Daimler-Chrysler has identified five clear phases in future energy for vehicles: first, optimisation of the internal combustion engine; second, improvement of conventional fuels; third, CO²-neutral biofuels; fourth, hybrid vehicles; and fifth, fuel-cell technology (EN, 2004).

Translating this approach to construction presents the following possible science and technology agenda:

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Optimise conventional construction technologies; Mainstream fringe technologies; Integrate hybrid technologies; Create a biotechnology platform; and Develop nanotechnology applications.

However, for this can be done, it is necessary to provide the different areas of analysis below with a conceptual, theoretical and methodological sound basis to build upon and further develop the science and research areas. In short, the drivers, issues and trends must enable the construction of new theories, methodologies and policy frameworks in order for the technologies to be relevant.

Optimise current construction technology Conventional construction methodologies and technologies will continue to form the most significant technology application within the construction sector for many years still to come. In developed economies, conventional construction technology forms the basis of the vast inventory of existing building stock that constitutes – and will continue to constitute – the built environment. In developing economies, a shortage of skills and technology will result in the use predominantly conventional technology within the construction sector in the short and medium term. Since much of the construction work in the short to medium term will rely on existing standards and incremental changes, a significant challenge is to exploit conventional construction technology to extract as much value as is still possible. Three strategies do however stand out with regard to optimization: The better exploitation of materials – a strategy is required to promote the better use of construction materials

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through the use, for example, of information produced through many years of materials research. Such a strategy will improve the competitiveness of material suppliers by developing more efficient and reliable use of materials and products in construction; improving the interface and interactions between materials; encourage the faster exploitation of new materials and techniques; lead to a reduction in cases of inappropriate use of materials; result in improved co-operation between different materials supply sectors; lead to greater take-up and appreciation of research by the construction sector; and promote materials information that more closely addresses industry needs.

Modular design – although this has more to do with design strategies, contemporary ICT software facilitates and eases the adoption of modular design.

Modular design seeks to integrate all materials into a common dimension to minimise and eliminate waste caused by dimensional incompatibilities. Modular designs – and the development of a modular construction component standard – can, without doubt, lead to significant benefits in terms of construction waste reduction and its concomitant disposal to landfill sites.

Adoption of life cycle analysis – closing the material loops, a method that has been extensively adopted in many production technologies within the manufacturing sector, has as yet had little success in the construction sector.

Life cycle assessment (LCA) focuses on closing material loops, addressing future extraction of resources, and taking a longer view of the lifespan of a building whereby the adoption of more efficient but more expensive technologies can be amortised over the life of the facility. The adoption of LCA will also include ensuring that the extraction, production and use of

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resources will be harmless throughout the entire manufacturing and in-use process, including materials dissipation at each stage in the material cycle.

Mainstream ‘fringe’ technologies A number of technologies are fairly well developed but under-utilised: ‘mainstreaming’ of including these technologies as a fundamental part of conventional construction practices can bring about significant benefits for the construction sector as a whole. They include: Passive technologies – these are technologies that are largely vested in the vernacular construction and building tradition of a country and have matured over many years in response to local conditions and traditions. These technologies offer advantages only gained through years of experience and continual development and therefore are adept at meeting local climatic conditions while minimising resource use. Although they have fallen into disfavour, South Africa has a vast inventory of passive technologies derived from the indigenous vernacular tradition as well as the incorporation of imported traditions that could serve as the basis for contemporary passive technological development.

Contemporary passive technologies include maximising the local renewable resource opportunities (solar, wind, biomass, rain, groundwater, and earth) in the vicinity of the building. They also include the use of a range of technologies aimed at saving natural resources such as low-flow sanitary fittings and low-energy appliances and fittings as well as photovoltaics and fuel cells.

Recycling technologies – these technologies are those centred on the three R’s: reduce, reuse, and recycle. The adoption of this strategy inherently follows the adoption of life-cycle thinking inasmuch as it focuses on the prevention and recycling of

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waste. In addition, experience in the E.U. has demonstrated that recycling activities are also a source of growth and job creation. The recycling business in Europe is estimated to be worth some €100 billion and employs hundreds of thousands of Europeans (ETAP, 2006).

Significant but patchy progress has already been made internationally with the recycling of conventional construction materials such as brick, steel, concrete, aluminium, glass, timber, gypsum board, etc. A limited amount of recycling and reuse occurs in South Africa with the biggest market involving the reuse of collectible ‘antique’ construction products particularly those from the Victorian and Edwardian periods.

There are however other products and materials such as plastic polymers, packaging waste recovery and recycling, and the recycling of more complex products or materials such as batteries, accumulators or electric and electronic equipment where new technological solutions are required.

One innovative solution includes the use of plastic from recycled, pirated CDs to make furniture.

Information and Communication Technology – although ICT is generally applied within the construction sector, in the main its application is limited to computeraided drafting, 3-D presentation drawings, and some limited simulation applications.

It is widely believed that CAD and CAM will significantly influence technological change within the construction industry and dramatic improvements are therefore expected within the field and the application thereof. The effective application of CAM is possible through the interfacing of CAD software with computer-numericalcontrol (CNC) machines. This interface relies on Bezier algorithms as compared to the more commonly used non-uniform

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rational B-spline (NURBS) algorithms used in CAD packages. In addition, the advanced modelling, analysis and visualisation software models surfaces rather than solids which ensure greater component precision.

I mproving the per for mance characteristics of infrastructure is one of the key capabilities of ICT. For example, the CaRB (Carbon Reduction in Buildings) project in the UK is a £5.4 million four year research activity aimed at using computer models to pinpoint effective ways of cutting carbon emissions arising from energy use in buildings (CIRIA, 2005). The aim is to develop models that will predict how much carbon can be saved by incorporating different energy efficiency or renewable energy measures into different types of residential and non-residential buildings. Although there are many software programmes that are capable of calculating, for example, energy usage, the use of ICT to virtually construct and test infrastructure prior to construction should become standard practice.

Control systems and computer systems are increasingly used to measure, adjust and optimise the operating systems of infrastructure. These technologies will monitor room usage, temperature, humidity and light and make any number of adjustments to ensure that optimal working conditions are maintained. Underutilised systems can be switched off to save energy, or placed in a stand-by mode.

Renewable energy technologies – the next frontier for renewable energy must be the democratisation of electricity generation through the use of smaller, cheaper and sturdier solar panels and wind turbines for the home. Residential-scale electricity generation effectively puts production and consumption together by giving facility owners the option of living on or off the grid.

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Modern methods of construction – refers to a re-emerging technology that relies extensively on ICT and off-site manufacturing to overcome the problems experienced by previous generations of manufactured or industrialised systems.

Richard (2006) in a paper “Industrialising the construction industry in developing economies: R&D of strategies and technologies” argues that each time a facility is constructed in the conventional manner a new business entity is set up to undertake and deliver the project. Therefore each project is a prototype and consequently very little of the knowledge generated by previous experience is applicable and used.

The conventional process sets up a team that occupies itself with more than the requirements of the project because it has to create a new entity for each project type rather than work off an established base.

Modern methods of construction (MMC) allow the cost of technology generation through R&D to be amortised because the technology is used more than once and/or it reduces the number of operations required to deliver the performance requirements.

The oft-used argument that industrialised building is boring is not valid because it is the details that are standardised, not the building. Essentially it should be a kit of parts consisting of very sophisticated components. These components are either shipped to the site and assembled on the site or are assembled in the factory and shipped as complete units to the site.

MMC favours undertaking in the factory the complex work in a building so that quality and time can be more effectively controlled. The work on site should be the more simple operations. An alternative to this methodology is taking the factory to the site (eg. extruding jointless aluminium gutters or roofsheets on site to fit the specific application). Designers can use the system

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or combinations of systems best suited to the projects performance requirements.

The resultant advantages are the flexibility of the product (floor panel can be a wall panel can be dismantled), the flexibility of the tool (computer-aided manufacturing), the multipurpose nature of the system, and the number of combinations possible (like music notes).

Integrate hybrid technologies There are a number of technologies developed by the military and NASA that are only now becoming available to the general market. Innovative materials formed a keystone of that development.

Hybrid combinations – essentially this application utilises a number of technologies to support and supplement each other. Classically this will incorporate, for example, a combination of energyproducing technologies such as grid, solar, and biodiesel. As the individual technologies improve and attain higher efficiencies, the user will have the option of converting to the most appropriate technology for the location. The same situation will apply to water harvesting and recycling.

Innovative materials – technological advancement and productivity in material science has reached the high levels of both quantity and quality that enables its use in the general market. Examples include making translucent yet insulated skylights from featherweight gel, high-performance ceramics strong enough to be used as body armour, and a blend of rubber that’s controlled by microprocessors and can form breathing curtains and windows.

Applications already in use include taking natural light into darker sections of a building through fibre-optic bundles connected to sunlight collectors on the roof.

In addition, many innovative products can be made from conventional materials,

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such as the use of paper-tubes for ceiling panels, partitions, and even load-bearing elements such as columns and roofs.

Create a biotechnology platform An accepted academic definition of biotechnology is “the application of scientific and engineering principles to the processing of materials by biological agents to provide goods and services” (OECD, 1982).

Biotechnologies are fundamentally based on utilising natural processes: one branch of biotechnology seeks to imitate natural processes hence its name ‘biomimetics’.

Industrial biotechnology seeks to replace traditional catalysts and transformation processes, many of which are polluting, with newer, environmentally friendly processes based on living organisms. It aims to reduce pollution inputs – such as raw materials and energy – and at eliminating or at least reducing waste generation in manufacturing sectors. Industrial biotechnology can also enhance resource efficiency and lower production costs thereby contributing to competitiveness and enhanced sustainability. Although the human health sector was the first to encounter biotechnology, many argue that the long-term importance of the environmental opportunities and needs for biotechnology are equal to if not greater than the significance attached to health and agro-food biotechnology (OECD 1996). There are those that argue that biotechnology is a new technological paradigm that will lead to far-reaching changes throughout the economic system and society and rate its impact as equal to that of electricity in the 19th century and ICT in the 20th century (OECD 1996).

Biotechnology – within the construction sector implies utilising natural processes and systems in infrastructure delivery in a manner that integrates it with

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natural systems. Technologies included in this category include bioremediation, a technology that uses plants to extract harmful by-products from the soil in order to release the site for redevelopment.

Biotechnology can also be applied in producing a new generation of construction materials, such as biocomposites capable of biodegrading over a period of time, or natural fibre composites using natural polymers. The use of natural polymers can also be used to develop new plastics for construction applications. The raw materials for these composites are all sourced from renewable resources.

Biomimetics – includes mimicking or replicating natural processes and systems in new applications. Examples include replicating the adhesive mechanisms of mussels to glue buildings together, or utilising the process of photosynthesis to harness the sun’s energy. Apart from processing waste, taking up and processing storm water, and assisting with heating and cooling, natural systems are also recyclable and biodegradable facilitating the construction of a fully deconstructable facility.

Biofiltering – this technology captures airborne pollution inside buildings and converts these pollutants into harmless byproducts. Biofiltering employs a combination of plant and microbial processes to convert one system’s waste products into another’s nutrients.

Biofuels – this technology uses plants, such as the Jatropha plant, to produce biodiesel which can then be used for generating electricity as well as for heating and cooking. The Jatropha plant is rich in oil and can produce clean fuel, while the plant can also reduce wind and water erosion of soil which is a major problem in many parts of the world. In addition the by-products from processing the Jatropha plant into

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fuel make excellent fertiliser (EN 2004).

Other organic material can also be used to produce biodiesel with up to 67 per cent derived from energy plants and the rest from reprocessed agriculturally-derived waste such as wood chips.

Develop nanotechnology applications The revolution in nanotechnology – science dedicated to building materials from the molecular level – holds significant promise for an entirely new generation of construction products and materials.

Energy – nanotechnology has the potential to improve every aspect of the energy sector, from exploration, recovery, generation and transmission. The opportunities include boosting battery life.

Self-cleaning elements – is one of the promising areas for the application of nanotechnology is. Although a range of self-cleaning products coated with titanium dioxide, including windows and ceramic tiles, are already available in the market they focus mostly on the practical value rather than the environmental value.

Nanotechnology offers the opportunity of breaking down vehicle exhausts and making pavings that clean the air. The catalytic properties of titanium dioxide become active when it is applied in a very thin layer, or in microscopic particles. Tests using photocatalytic concrete and cement demonstrated a reduction of nitrogen oxide levels of up to 60 per cent and encouraged the EU to earmark $2.27 billion to develop ‘smart’ construction materials that can break down nitrogen oxides and other toxic substances (Ritter, 2005). Self-repairing and self-regulating membranes feature in similar vane.

New structures – research work at IBM Research have published findings showing that a surprising range of nanostructures can be fabricated using a new self-assembly

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method (Bullis, 2006). The process depends on the ability to make uniform nanocrystals which enable the production of novel structures. Future applications could include new materials for more efficiently converting heat and light directly into electricity. Lightweight nano-based composite materials can reduce the average weight of an automobile by more than 70 per cent while increasing its strength by 4-5 times (Adams, 2006). These are completely new materials that have never been seen before and the potential for more materials is great.

Cost-effective and high-performance water treatment systems – nanostructures offer substantial improvements to existing water purification paradigms and to the development of new ones.

This is possible through the engineering of a new class of nanomaterials such as reactive membranes that are capable of remediating organic waste in water. Highperformance nanoscale catalysts are also available for treating particularly challenging contaminants that must be removed to very low levels in water. In addition, nanoscale magnetic particles have been developed

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that have strong sorption interactions with arsenic species that holds the promise of dramatically reducing arsenic levels in water.

Nanotechnology offers significant potential in developing countries where potable water quality is a major concern.

Conclusion As the Scientific Advisory Board of the UN Secretary-General noted, “there is a clear need to demonstrate that science, technology and innovation (STI) can be mobilized to gain a clear understanding of the world and its evolution, but also to operationalize changes, such as a transformation towards local low carbon economies or sustainable urbanization” (UNESCO 2015). They noted that “science can assist with decision-making and contribute to solving critical problems such as access to energy, health care, climate change, and biodiversity loss and food security” (UNESCO 2015).

Science, technology and innovation is ultimately a core component of resolving the contradiction in Dicken’s Tale of Two Cities.

References

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Bullis, K. 2006. “Nano building made easy”, Technology Review, MIT, January 05, 2006.

CIRIA 2005. New programme targets 50% carbon emissions reduction. [Online] Available from: http:// www.ciria.org/ [Accessed: 2005/10/06].

DACST 1996. White paper on science and technology. Pretoria: Department of Arts, Culture, Science and Technology.

Davis, K. 1966. Human society, New York: The Macmillan Company.

Dickson, D. 2005. “Will 2005 be the year of ‘science for development’?” [Online] Available from http:// www.scidev.net/ [Downloaded: 2005/13/01].

DST 2000. National research and technology foresight. Pretoria: Department of Science and Technology.

DST 2002. South Africa’s national research and development strategy. Pretoria: The Government of the Republic of South Africa.

EN 2004. “Leading auto group responds to sustainability challenge”. Engineering News. [Online] Available from: http://www.engineeringnews.co.za/components/ [Accessed: 2004/08/16].

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EPA 2003. Lean manufacturing and the environment. Washington: Environmental Protection Agency.

ESRC 2011. Evidence based policy: where it came from and where it’s going. [Online] Available from https://www.kcl.ac.uk/sspp/departments/politicaleconomy/research/cep/pubs/papers/assets/wp1.pdf [Downloaded: 2015-01-12].

ETAP 2006. “Recycling technologies; clean, clever, competitive.” Newsletter of the EU Environmental Technologies Action Plan (ETAP), Issue 3, January 2006.

Friend, G. 2005. It began with a dot: product regulation and future markets. Natural Logic, Inc., [Online] Available from: http://natlogic.com/ [Accessed: 2015/08/12].

Futurecasts 2001. “Restatement and evaluation of Futurecasts.” Futurecasts Vol. 3, No. 1, October 1, 2001. [Online] Available from: http://www.futurecasts.com/Default.htm [Accessed: 2015/08/12].

Head, B. 2009. Evidence-based policy: principles and requirements. [Online] Available from: http://www. pc.gov.au/__data/assets/pdf_file/0007/96208/03-chapter2.pdf [Downloaded: 2015-01-15].

IEA 2014. Key world energy statistics. Paris: International Energy Agency.

Larsen, P. and von Ins, M. 2010. “The rate of growth in scientific publication and decline in coverage provided by science citation index.” Scientometrics 84:575-603. DOI 10.1007/s11192-010-0202-z OECD 1982. Biotechnology: international trends and perspectives. Paris: Organisation for Economic Cooperation and Development.

OECD 1996. “Introduction: on the pervasiveness of biotechnology.” STI Review No.19. Paris: Organisation for Economic Cooperation and Development.

Policy Research Initiative 2002. ”Canada’s cities.” Horizons 5(1):1-2. Public Works and Government Services Canada.

Richard, R. 2006. “Industrialising the construction industry in developing countries: R&D of strategies and technologies”, Papers read at the international symposium Construction in developing economies: new issues and challenges, January 18-20, 2006: Santiago: Chile: CIB W107 Construction in Developing Countries.

Ritter, K., (2006), “Smog fight aided by self-cleaning elements”, Washington Post, July 21, 2005.

South Africa Info 2014. “South Africa ‘turning the corner’ on R&D spending.” [Online] Available from: http://www.southafrica.info/about/science/research-110414.htm#.VcsgnbAViUl [Accessed: 2015/08/12].

Sutherland, W., Bellingan, L., Bellingham, J., Blackstock, J., Bloomfield, R., et al. (2012). “A CollaborativelyDerived Science-Policy Research Agenda.” PLoS ONE 7(3): e31824. doi:10.1371/journal.pone.0031824 UN 2005. Millennium ecosystem assessment. New York: United Nations.

UNESCO 2014. R&D data: investing in a better future. Montreal: UNESCO Institute for Statistics.

UNESCO 2015. “Science, technology and innovation: critical means of implementation for sustainable development goals.” [Online] Available from: http://www.unesco.org/new/en/media-services/single-view/news/sceince_technology [Downloaded: 2015/05/05].

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he combinations of materials used to build the main elements constituting the building envelope — roof, walls and floor — are referred to as construction systems. Reardon and Downton (2013:1) note that “they are many and varied, and each has advantages and disadvantages depending on climate, distance from source of supply, budget, maintenance requirements and desired style or appearance.”

Reardon and Downton (2013:1) note that “the environmental performance of a construction system is determined by life cycle or ‘cradle to grave’ analysis of the impact of the individual materials used in it. Preliminary decisions about construction systems are often made during the early design stages of a project whereas analysis of their environmental performance often occurs later during the detailed specification stage. Making decisions in this order can limit the range of achievable and cost effective environmental outcomes.”

They suggest that when choosing a construction system the following important factors need to be considered: • role in improving thermal performance • durability compared to intended life span • life cycle cost effectiveness • life cycle energy consumption • source and environmental impact of all component materials and processes • availability of skills and materials • maintenance requirements • adaptability and reuse or recycling potential • distances and transport modes required for components and system (road, rail or ship).

Reardon and Downton (2013:2) recommend that decisions should also “be guided by life cycle assessment, which is able to take into account a material’s environmental emissions and depletions from ‘cradle to

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grave’: source, extraction, manufacture, operating performance and end of life disposal or reuse.”

Critically they argue that “there is no single best solution. Any combination of materials should be assessed in light of the above factors to arrive at the most appropriate compromise. Every application is unique and should be individually evaluated. Exceptions are the norm — particularly in innovative design solutions.”

Reardon and Downton (2013:2) note that “energy used for heating and cooling accounts for about 40% of home energy use.

Because the mass of materials influences thermal performance, embodied energy and many of the other factors listed above, it is a primary consideration from the earliest design stages.”

Light steel frame building technology Light steel frame building is a building method that makes use of thin gauge cold formed galvanized steel sections, screwed or riveted together to form wall panels, trusses or joists. Wall panels are clad on both sides to form loadbearing or partition walls. Light steel framing originally (1960’s, USA) made use of 2 to 3mm thick cold rolled steel sheet.

The material was generally roll-formed into cold formed channel sections to be used as the elements of the wall frames or roof structures. As is still the case with timber frame building, each element had to be measured, and cut to size, before assembly.

As thinner gauge high strength steels were developed, and computer software packages became more sophisticated, light steel framing was taken to the next level by development work carried out mainly in Australia – computer programmes that could be run on personal computers were developed to carry out the structural and geometric design of the light steel frame structures, and also to control the

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rollforming equipment to manufacture the sections required. Not only is each element of the structure now automatically cut to exact length, but the holes for fasteners are punched in the sections, and indented to allow a smooth fit for cladding and lining boards that have to be fixed to the frames.

Use is made of high strength galvanized steel sheet (Grade 550, or 550MPa yield strength) – some 60% higher strength than normal structural steel. This makes it possible to use thinner gauge material (typically from 0.8mm to 1.2mm for low rise building) to carry the loads.

The system software also prints out all the plans and drawings required for erection of the steel frame of the building.

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Elements of a light steel frame building Materials used in LSFB The following are the most widely used materials for LSFB. High strength galvanized or zinc-aluminium coated steel sheet High strength galvanised or zincaluminium coated steel sheet is used to manufacture the components of the light steel frames, trusses and joists. As is the case with most steel products, it is readily available.

Iron is the 4th most abundant element in the earth’s crust (Darling 2007). As result of the recyclability of steel, and a well developed recycling industry, a growing percentage of steel is produced using steel

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scrap – at present accounting for some 30% of all new steel production (World Steel Association 2015). This, coupled with the durability and the optimization in the use of steel for LSFB, renders it a sustainable material.

Fibre cement board Fibre cement board is combination of cellulose fibres, sand, and cement. As external cladding, it is durable and requires little maintenance once installed. It can withstand high levels of moisture, intense heat, and frost.

Fibre cement is not susceptible to termites or rot, adding to its durability. Most often used for external cladding, either as flat sheets or building planks - with either smooth or textured surfaces. Fibre cement comes in a neutral grey tone, and has been seen on the façades of every kind of building from family homes, shopping centres and school buildings.

Glasswool Glasswool is the most commonly used product in LSF buildings for thermal and acoustic insulation. It is manufactured by melting sand and cullets (recycled glass) at 1450°C in an electric furnace and then conditioned in a gas fired hearth. The fibre is formed by centrifugation through drilled circular baskets, where after binding products and other elements specific to the usage are added. No CFC`s or HCFC`s are produced in the manufacturing process. The fibres are gathered in a mat form in a collection chamber and then conveyed to an oven, where it is cured under controlled conditions to the required thickness and density.

Glasswool is environmentally friendly, recyclable, light weight and easy to handle, maintenance free and it offers a long product life. It is available in rolls or cut lengths (bats), in a range of standard thicknesses.

HOUSE ENERGY JONES

Gypsum board Gypsum board or plasterboard consists of gypsum sandwiched between two layers of paper liner. It is used as internal lining for walls and ceilings. By varying additions to the content of the core and the type of liner used, boards are produced to suit different requirements, such as fire resistance, sound reduction, water resistance and impact resistance.

Why is light steel frame building technology regarded as sustainable?

Light steel frame building (LSFB) has been developed to overcome many of the problems and deficiencies of heavy masonry building, and to comply with 21st century energy efficiency requirements and practices.

Energy efficiency: there are two types of energy involved when it comes to buildings – embodied energy and operational energy.

It is generally accepted that the total energy requirement of a building over its design life will consist of 20% embodied and 80% operational energy (Milne and Reardon 2015).

• Embodied energy: this is all the energy involved in mining raw materials, manufacturing the building components and delivering it to site. We do not yet have a comprehensive South African embodied energy inventory available (the CSIR is working on it), but based on Australian figures, the embodied energy of LSF walls is about 45% of that of heavy masonry walls (Milne and Reardon 2015).

• Operational energy: Through proper insulation of external walls, LSF buildings are more energy-efficient than heavy masonry buildings. The CSIR carried out a research project comparing the thermal performance of a single storey LSFB house with an identical uninsulated masonry dwelling (Conradie and Kumirai 2012). Using the Ecotect™ V 5.6 building thermal analysis programme, it was found

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that the LSFB will result in uncomfortably high or low internal temperatures 28% of the time, compared with a slightly higher 32% for the masonry building.

But when heating or cooling is applied to change the internal temperatures to comfortable levels, the true advantage of LSFB becomes apparent – it was concluded that a LSFB will on average (in all the climatic zones of South Africa) need only 44% of the electricity required for heating and cooling compared to a masonry building.

Lower mass: Walls in a LSFB has a much lower mass than masonry walls – a LSF wall has a mass of some 36 kg / m² of wall – including the steel frame, external cladding, insulation and internal lining) - compared with 450 kg / m² for a double leaf plastered brick wall. This offers benefits in logistics, as 90% less material (by mass) has to be transported and handled for an LSF building. Apart from the logistical benefits, the reduced mass also reduces wear and tear on South Africa’s already over-burdened roads.

Materials for the walls of a 200 m² (floor area) brick house have a mass of some 180 tons (bricks, sand and cement), compared with the 11 tons for a LSF house (SASFA 2015).

Quality assurance: A lot of the quality assurance required has been taken off site with LSFB. Materials are manufactured in factories where quality control is exercised.

Most components are cut to size before delivery to site, ready for installation.

There is no mixing of raw materials on site, eliminating possible errors through lack of control to a large extent. Offsite manufacturing is a emerging as a national objective in many countries, including South Africa as it creates decent factory-based jobs and reduces material waste as part of the Lean Construction objective.

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Speed of construction: Provided proper detail planning has been carried out, LSFB can be built very quickly. As an example, all the major fast food chains have decided to build their new outlets using LSFB. These buildings are being fully completed in 3 months, compared with at least double that time had masonry building methods been used. From a commercial perspective this enables tenants to take occupation much earlier, but it also reduces the contractor’s preliminary and general costs on site.

Water efficiency: LSFB is a dry process, and hence it offers savings in water consumption. Water in the manufacturing of materials used in LSFB, is used in factories where careful control is exercised to recycle and to prevent wastage of water.

Recycling: Steel is said to be the most recycled material in the world. Some 30% of all new steel is manufactured using scrap, with a significant energy saving (World Steel Association 2015). An interesting aspect about the recycling of steel is that the new product manufactured is not of a lower standard than the scrap used in the process.

Conclusion Reardon and Downton (2013) provide the following rule-of-thumb for choosing a construction system: Thermal mass • Combine high and low mass construction within the building to maximise the benefits of each (see Thermal mass; Passive design).

• Use heavyweight systems (such as concrete floors) internally and lightweight systems externally for lowest lifetime energy use.

• Where solar access is unachievable or undesirable (e.g. steep south facing sites, overshadowed sites or tropical locations), insulated lightweight construction is

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often more efficient as it responds rapidly to mechanical heating or cooling.

Maintenance • The durability of well-maintained lightweight systems is equivalent to heavyweight systems.

• Poor maintenance can reduce life span by up to 50%, negating embodied energy savings and doubling materials consumption.

• Reliable maintenance regimes for the whole life cycle are a critical consideration when selecting external cladding systems Source and use of materials Choose materials that are: • life cycle certified by an accredited scheme (e.g. GECA, Green Tick, EcoSpecifier) • renewable in preference to those from finite resources • low in embodied energy (per unit area of building) unless that embodied energy content can be amortised over life span through operating energy savings • certified as not threatening to biodiversity • low toxicity in both production and operation • high in renewable or recycled content provided durability and performance

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are appropriate for life span (e.g. fibre cement cladding, sustainably managed forest timber frames or recycled plastic/ sawdust decking).

Design for: • deconstruction and reuse, or recycling to amortise the life cycle impact of materials high in embodied energy or non-renewable resources (where these materials are the best option) • structural efficiency to minimise overall materials use, waste, transport and processing • materials with similar and appropriate life spans (e.g. use fixings, flashings or sealants with a similar life span to the material being fixed) • construction systems with known low wastage rates and environmentally sound production processes (see Waste minimisation).

Transportation • Avoid systems with a high on-site labour component in remote projects to reduce travelling.

• Use locally made products where possible to reduce transportation.

• Building systems with low mass per unit area of building offer logistical benefits.

References

•

•

• • •

Milne, G. and Reardon, C. 2015. Embodied energy. [Online] Available from: http://www.yourhome.gov. au/sites/prod.yourhome.gov.au/files/pdf/YOURHOME-3-Materials-1-EmbodiedEnergy-(4Dec13).pdf [Accessed: 10/23/15].

Kumarai T., and Conradie D. 2012. Thermal Mass vs. Insulation Building Envelope Design in Six Climatic Regions of South Africa. The Green Building Handbook South Africa, The Essential Guide, Volume 4, pp 201-215.

3. Reardon, C. and Downton, P. 2013. Construction systems. [Online] Available from: http://www.yourhome.gov.au/materials/construction-systems [Accessed: 10/23/15].

4. "Elements, Terrestrial Abundance". www.daviddarling.info. Archived from the original on 10 April 2007.

5. World Steel Association 2015. World Steel in Figures 2015. World Steel Association.

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Viega Fonterra Base Flat 12

Especially fast, especially flat and especially for renovation.

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For under floor heating construction heights as low as 35 mm Because three ideal components meet and combine right here: The ND 11 or smart studded panels, the extremely flexible Fonterra PB pipe 12 x 1.3 mm and the special Fonterra Base Flat 12 screed admixture. This makes extremely thin cement screeds with only 15 mm stud covering possible.

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New screed system – ultra flat and quickly accessible Fonterra Base Flat 12 Surface heating: low installation height despite the cement screed When installing surface heaters in existing buildings, specially coordinated systems often need to be used due to the structural conditions. This can be very expensive in some cases. With the Fonterra Base Flat 12, Viega is now offering an economic alternative. The new system is processed like a standard wet system – but with a tested addition to the cement screed. As a result, the system is only 35 to 45 mm thick.

Wet design surface tempering systems are mostly solely used in new builds. As a general rule, there is sufficient installation height available there. However, the reality is frequently different when renovating existing buildings. The load capacity of the floors is often restricted here. To date, this problem could normally only be solved by dry systems or with sealing compounds, as conventional screed always requires a covering of at least 30 mm.

With the Fonterra Base Flat 12 surface tempering system by Viega, low installation heights can now also be realised in screed constructions: With the coordinated combination of system studded panels, 12 x 1.3 mm polybutene pipes and a screed covering, the total installation height is still only 35 mm. If a Fonterra studded panel, which is insulated during manufacture, is used, then the complete installation height is 45 mm. In both cases, 15 mm of screed is enough of a covering on the studded panel to fulfil all requirements for private residential construction up to a load capacity of 2 kN. Lower weight and drying times With the low installation height, the weight of the new floor is also reduced. Fonterra

Base Flat 12 is the best thing to use in buildings with wooden beam ceilings.

The screed additive checked by Viega also provides a considerably shorter drying time than for a conventional screed: Instead of 21 days, the curing process for Fonterra Base Flat 12 installations is finished after just five days. From the sixth day, dry heating can be started.

Very good heat transfer The heat transfer is optimal with the extraflat Fonterra surface tempering systems: Due to the perfect location of the PB pipe in the studded panel, the pipe is completely enveloped by screed. The loss- free heat transfer to the room ensures a reduction in heating costs, beyond the system’s typical energy saving.

About the company: Worldwide, more than 3,500 people are employed by the Viega group, which is among the leading manufacturers of installation technology. Viega is working to continue its long-term success at nine locations. While production is concentrated at its four main sites in Germany, the McPherson/USA group manufactures solutions specially designed for the North American market. And the Wuxi/China site focuses on production for the Asian market.

Installation technology as a core skills drives growth forward. Pre-wall and drainage technology belong to the product range alongside piping systems. The range consists of approximately 17,000 articles, which are used nearly everywhere: In building services installations, in utilities or in industrial plant construction.

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Institute for Timber Construction

Pre-Fabricator Timber Roof Structures

The roof structure is arguably one of the most important construction elements of any residential building, protecting the occupier’s property, finishes and inhabitants from the elements. It is also one of the largest, heaviest and most costly structural components in any home design.

Therefore it is logical to expect that a lot of planning, design and know-how would be invested in order to create an aesthetically pleasing, sound structure that will safely carry the induced loading, as well as offering acceptable longevity for the lifespan of the building.

Although the above sounds logical, sadly many building owners choose price over quality with regards to workmanship and materials, which can lead to costly, disastrous and sometimes lifethreatening situations.

The ITC-SA makes sourcing of reputable roof fabricators, erectors, inspectors and engineers easy – all the consumer needs to do is to contact the institute directly or visit its website. The ITCSA website provides a comprehensive list of all accredited members on a national basis.

Pre-fabricated roof trusses shall at all times be in accordance with the rational design requirements given by the engineer, as well as the SANS requirements below. To confirm compliance, an engineering certificate will be required on completion of any roof structure:

• SANS 10400- Part L • SANS 10243 • SANS 10163 • SANS 1783- Part 1 and 2 • SANS 51075 • SANS 3575 • SANS 10096 Pre-fabricated roof trusses can only be approved when a rational design is available confirming that the material and truss design meet and/or exceed the SANS requirements.

Prefabricated roof trusses are cut by advanced, specially designed machinery and are therefore far more accurate than their hand-made counterparts. Prefabricated trusses, covered by a rational design, will also use less timber and will comply with all regulatory requirements, assuming they are designed by an ITC-SA accredited professional.

Internal investigation and findings by the ITC-SA has confirmed that 90% of hand/site made trusses do not comply with the relevant building regulation and SANS material and design specifications.

Research has also confirmed that hand/site made timber roof trusses are on average 20% more expensive than pre-manufactured timber roof trusses.

Pre-fabricated roof trusses come with guarantees in the form of a manufacturing warranty and an engineer’s certificate, which the owner may call upon to have the roof structure repaired.

Head Office: SAFCA Building, 6 Hulley Rd • Po Box 686, Isando, 1600 tel: +27 (0) 11 9741061 • fax: +27 (0) 11 392 6155 • enquiries@itc-sa.org • www.itc-sa.org

RAINWATER HARVESTING Jeremy Gibberd

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outh African is a water scarce country and studies indicate that 98% of available water supplies are already exploited. In addition, a number of South African cities, such as Johannesburg, are vulnerable to water shortages if a severe drought occurs (Department of Environmental Affairs, 2011).

Therefore, it is important to understand how water can be used as efficiently as possible and to explore alternatives to municipal piped water supplies. Rainwater harvesting provides a simple way of capturing and storing water which can be used to supplement, or replace, municipal water supplies. It can be used to reduce the pressure on municipal systems and provides a valuable buffer for households and businesses against drought and local water shortages.

This chapter describes how rainwater harvesting can play a valuable role in increasing the resilience and sustainability of water supply. The different types of

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rainwater harvesting system are described and advantages and disadvantages of the technology listed. Some of the key design and operational principles are presented to enable the practicality and applicability of systems to be understood. Finally, conclusions are drawn and policy, and other, recommendations are made to support the increased adoption of rainwater harvesting systems in South Africa.

The Water Context The United Nations Environmental Programme (UNEP) estimates that 450 million people in 29 countries suffer from water shortages (UNEP, 2008).

Within Africa, UNEP indicates that many countries experience physical or economic water scarcity. Economic water scarcity is experienced in countries where access to water may be limited by human, institutional or financial capital, even though water is available locally. This is shown in green on figure 1. Countries in light orange, such as South

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Figure 1: Areas of Physical and Economic Water Scarcity in Africa (UNEP 2014)

Figure 2: Cereal productivity in Sub-Saharan Africa by 2050 under an IPCC climate change scenario (UNEP 2014)

Africa, are nearing physical water scarcity, and countries in deep orange (also South Africa) experience water scarcity (UNEP, 2014)

and the location of many towns and cities away from larger water courses. This has meant that water may have to be pumped long distances in order to provide supplies in cities (Department of Water Affairs and Sanitation, 2012).

The South African General Household Survey indicates that 12.8 million households currently have access to piped water (Statssa, 2014). This represents 84% of the population, indicating that a significant proportion of the households still do not have piped water. The survey also indicates that households are becoming less satisfied with water services and that households indicating that they had received good water service dropped from 76% in 2005, to 63% in 2013.

The quality of water services is related directly to water infrastructure and a range of challenges have been identified by the Department of Water and Sanitation.

These are listed briefly below (Wensley & Mackintosh, 2015).

Climate change will exacerbate water scarcity in some regions and UNEP suggests that by 2025, two-thirds of the world’s population and 25 countries in Africa will be experiencing water-stress (UNEP 2008). Projected warming of between 0.2°C and 0.5°C per decade will result in 10% less rainfall in interior regions of Africa, resulting in agricultural yields being reduced by up to 50%, as shown in figure 2 (UNEP, 2014).

This will be experienced most acutely in semiarid margins of the Sahara along the Sahel and in the southern African interior. These changes will affect small farmers and poor people worst as their capacity to adapt, by accessing stored water, irrigated agriculture and alternative livelihoods, is limited.

The South African Context The availability of water in South Africa is affected by the uneven spatial distribution of rainfall, low stream flow in many rivers

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Poor water services planning.

• Aging water infrastructure with a rapidly increasing need for additional investment.

• Limited technical and engineering skills to plan and manage infrastructure.

• Reduced adequacy of existing water resources.

• Changing patterns in water demand.

• Increased energy consumption, and therefore, pumping costs.

These challenges affect the extensive water infrastructure network required for piped municipal water supply including water resources and bulk infrastructure and distribution infrastructure, as shown in figure 3.

While initiatives have been put in place to address this situation, a number of challenges are likely to persist. These include water outages when water infrastructure fails, water tariff increases to meet rising infrastructure and energy costs and water shortages resulting from changing and increasing water demands.

In addition, it is likely that there will be reduced capacity within existing water resources,

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SOLAR ELECTRICITY

such as dams, to meet demand as a result of droughts associated with climate change.

Finally, limited resources mean that water supply backlogs will take time to address and some households will continue not to have municipal piped water in the near future.

Given this situation, it is important that individuals, organisations and government work together to ensure that water supplies are inclusive, accessible, affordable, clean and reliable. A technology that can be used to support this goal is rainwater harvesting.

Rain Water Harvesting Rainwater harvesting is the collection and storage of rainwater for agricultural, domestic or industrial use. Rainwater systems usually consist of the following components: Collection: This is the area where rainwater is collected. This usually consists of roof surfaces but can also include other external hard surfaces such as sports and play areas and sloped land.

Filters: In order to remove debris and dust, simple filters are often included between the collection surface and storage tanks.

Figure 3: Infrastructure required for piped municipal water supply (Wensley & Mackintosh, 2015)

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6 5 Circulation: Water is transported through pipes or channels, such as gutters and downpipes, to the storage tank Storage: Tanks are used to store water and can vary widely in shape and size. They are usually located near collection surfaces.

Filtration: Where water will be used for human consumption, filtration systems may be included. These systems filter water pumped from storage tanks before it is consumed.

Usage: When stored water is required, this is drawn from water tanks and circulated to the point where it used. Rainwater can be used for irrigation, flushing toilets, cleaning and drinking and a range of other uses.

Advantages and disadvantages of rainwater harvesting While there are many advantages of rainwater harvesting systems, there are also some disadvantages. This section briefly outlines both the advantages and disadvantages of rainwater harvesting (UNEP, 2009).

Advantages Reduced flooding, storm water runoff and erosion as rainwater flows are captured and runoff is managed.

• Reduced requirement for imported water from other regions or countries where supply can be affected by other parties.

• Less energy is required for pumping water.

• The technology is simple and can easily be installed by unskilled labour in domestic situations.

• Increasingly cost effective to install as payback periods reduce as water tariffs for municipal piped water increase.

• Provides water where it is needed, such as within a building or to a landscape, reducing the requirement for piped networks.

• Can make use of existing structures such as rooftops, parking areas, playgrounds, parks and ponds.

SOLAR ELECTRICITY RAINWATER HAVESTING

• Has fewer negative environmental impacts compared to other water resource developments, such as dams.

• Water captured is clean and can be used for many purposes with little or no treatment.

• Physical and chemical properties of rainwater are superior to groundwater or municipally treated water that may be subjected to contamination or chemical dosing.

• Rainwater systems can be designed to co-exist with existing municipal supplies and reduce pressure on them.

• Storage of rainwater can provide a valuable buffer during planned and unplanned repairs and maintenance of municipal water supplies.

• Reduced water losses due to leaks, as these are more readily identified in the simple storage and piped networks that exist within a site.

• Improved water conservation as users are more aware of water stored on site and the limited capacity of this.

• Physical properties of water can be used as part of the built environment’s environmental control strategy. For instance, evaporation off water surfaces can be used for evaporative cooling.

Similarly, the high thermal mass of water can be used in passive environmental control strategies.

Disadvantages Rainwater harvesting tanks can take up considerable space.

• The costs of a rainwater harvesting system can be substantial. However, these costs may be justified by reduced, or avoided, payment for piped water from municipalities or other sources.

• Rainwater tanks, if not designed and maintained properly, can be a location where mosquitoes breed.

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6 5 The supply of water is dependent on • rainfall and, therefore, may not always be reliable.

• Large rainwater tanks, if not protected properly, can present a drowning risk for children or adult non-swimmers • Rainwater tanks may need cleaning if debris and dust are washed into tanks.

This can be addressed through effective filtration.

• If rainwater harvesting is widely applied there is a danger that this will affect existing drainage systems which may have less water and experience reduced flows.

Types of Rain Water Harvesting System Many different types of rainwater harvesting system exist. These are designed to respond to the local climate, site parameters and local requirements for rainwater. Some examples of the main types are outlined below (UNEP 2009).

Simple roof catchment system: This system consists of rainwater tanks which are linked to gutters and downpipes of smaller, domestic-scale buildings. Usually, water in these situations is used for garden irrigation, but can also be used for human consumption in remote areas where there is no municipal supply.

Institutional catchment systems: This system consists of one or more large rainwater tanks fed by a range of catchment surfaces. For instance, tanks may be fed by classroom roofs and hard playground surfaces, in the case of a school. Here water is usually used for landscape irrigation, but may also be used for cleaning and to flush toilets. It may also be filtered and used for human consumption in areas where potable water is not readily available.

Neighbourhood catchment systems: These systems capture rainwater that falls within a selected area of human settlement and catchment surfaces may include roads,

SOLAR ELECTRICITY RAINWATER HAVESTING

roofs, pavements and hard and soft surfaces.

Rainwater is usually directed to the lowest point of the neighbourhood, where it is stored in substantial ponds or subsurface tanks. Water in these systems can be used for irrigating parks, fruit orchards and vegetable gardens as well as for domestic use such as flushing toilets. These systems can be integrated effectively into urban areas by being located beneath urban squares where they can also be used to reduce local temperatures and the urban heat island effect.

Land surface catchment systems: These consist of subsurface tanks or ponds that are fed from land surface catchment areas.

Catchment areas here can be small (100200m2) or large (over 2ha). These systems usually have a filtration device to reduce the extent to which debris or silt from the land surface is washed into tanks. A version of this system, called a hafir, is used in dry arid areas, such as the Sudan to capture rainwater for irrigation, livestock and settlements and can be considerable in size (tanks can be over 250,000m3).

Agricultural catchment systems: There are a range of systems in agriculture for capturing and retaining runoff so that this can be used by plants and livestock. Very simple systems, which may not be strictly speaking rainwater harvesting systems, include swales and terracing, which retain runoff on site and direct this to plant roots. Very small dams in cultivated or wild landscapes are also used trap runoff and store this as drinking water for free range livestock and wildlife.

Design and Operational Considerations The design and planning of rainwater systems requires a detailed understanding of the local conditions, climate and water use requirements in order to ensure that the system is designed correctly and works

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efficiently. This section provides design and operational considerations in relation to rainwater harvesting systems (UNEP 2009).

Catchment surfaces The following design and operation considerations should be taken into account in relation to catchment surfaces.

• Smooth hard roof surfaces make the best catchment surfaces and include roofs made of metal or concrete.

• Catchment surfaces must be non-toxic and asbestos roofs and surfaces with coatings which include lead, chromium, and zinc-based paints/coatings should be avoided.

• Gravel and other forms of ballast are sometimes placed on flat roofs. In dusty locations, this is difficult to keep clean and as runoff may have high levels of silt these surfaces may not be suitable for rainwater collection.

• Catchment surfaces should be cleaned regularly and dust and other debris should not be allowed to collect. Access to catchment areas and a cleaning programme is, therefore, important • As far as possible, roofs should be clear of overhanging trees to avoid leaves gathering on the collection surface. In addition, animals such as birds should be discouraged from settling on catchment surfaces as their droppings contaminate water.

• If parking areas are used for collection, care should be taken to avoid any oil that may have leaked from cars from contaminating water. This can be addressed through oil traps and ensuring that water collected in these areas is separated from cleaner water collected from elsewhere (such as roofs).

Circulation The following design and operation considerations should be made in relation

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to circulation from catchment surfaces to rainwater tanks.

• Gutters and downpipes should be adequately sized to ensure that they cater for heavy downpours when these occur.

• Leaf screens or other basic filters can be fitted to rainwater goods to reduce debris from entering the system.

• Where collection areas include planting, such as roof gardens, outlets should be located to ensure that some water is retained for plants. This can be done by locating outlets above the lowest point of the collection surface to ensure that a portion of the subsurface water is retained.

Filters The following design and operation considerations should be made in relation to filters from catchment surfaces to rainwater tanks: • ‘First-flush’ filters direct initial flows of water from rainfall on a collection surface to waste to ensure that any debris or dust that is picked up does not contaminate stored water.

• An alternative system used is baffle tank, which has screens to filter debris and small settlement tank where silt can be captured and removed.

• These filters are an effective way of avoiding the need to clean rainwater harvesting tanks regularly.

Storage tanks The following design and operation considerations should be made in relation to rainwater tanks: • Storage tanks are the most expensive component of a rainwater harvesting systems so it worth investigating the best option. In simple rooftop systems, plastic or steel tanks located on a concrete base

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near a building are often used. In larger systems, water tanks can be underground and may be made of concrete.

Water has a high thermal mass and, therefore, can be used as part of the thermal design of a building. For instance, passive environmental control strategies including evaporative cooling and night time cooling of thermal mass can use a body of stored water to keep buildings cool in hot climates.

Sunlight stimulates the growth of algae, so storage tanks should be opaque, or located where they will not be exposed to direct sunlight.

Water tanks should include mechanisms for overflow which directs water elsewhere when tanks are full. Without this mechanism, there is a danger of tanks ‘burst’ as a result of water pressure.

The interiors of water tanks should be accessible so that these can be cleaned and any silt and debris removed.

PVC tanks can be damaged and may be moved easily when they are empty as they made of lightweight materials.

Therefore they should be located where they will not be damaged, or they should be protected, by, for instance, fencing.

Stay cables and locating outlets well above the floor of these tanks (to retain some water in the bottom of the tank) can also be used to avoid the tank being physically moved by people, livestock or high winds.

In large rainwater harvesting systems, where water is sourced from both roof and ground level hard surfaced it may be advisable to have a number of tanks rather than a single tank. This can be used reduce the size of tanks, allowing these to be accommodated more easily on a site.

It also enables water of different qualities to be stored and allows maintenance and repairs to be carried out more easily.

• Access to the tank should be screened, to avoid insects from entering the tank and breeding.

Filtration The following design and operation considerations should be made in relation to rainwater filtration: Where rainwater is used for irrigation or to flush toilets, it is not usually necessary to filter this. However, where water is used for human consumption, simple filtration systems can be used to ensure that water is clean.

Usage The following design and operation considerations should be made in relation to rainwater usage: • Rainwater is usually used for irrigation but can be used for washing and human consumption.

• As debris and silt settle on to the floor of the rainwater tanks, outlets should be located to avoid taking water from the very bottom of the tank and should instead source water a little above this, where water is cleaner.

• Water from storage tanks may require pumping in order for this to be used. A simple and environmentally friendly way of doing this is to pump water to header tank using an electric pump powered by photovoltaic panels. Water is then gravity fed from the header tank.

Conclusions and Recommendations A review of South Africa’s water situation indicates that it is important to explore alternative technologies and approaches that help ensure that there is an affordable, reliable and clean water supply. The relatively low cost and simplicity of rainwater harvesting systems make this an ideal option to investigate in many situations.

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Despite this, rainwater harvesting has not been widely adopted in South Africa. The following recommendations are made to support increased adoption of this technology: Research: Further research on the potential, and implications, of rainwater harvesting systems should be implemented.

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This should include GIS-based studies on rainwater harvesting potential, such as those carried out for Gaborone, Botswana (figure 5).

Guide: A simple, illustrated guide should be developed which explains what a rainwater harvesting system is, why it is important and how it can be implemented.

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Calculators: Simple calculators should be developed to support the design of rainwater harvesting systems. These should be made readily available and provide guidance on aspects such as the sizing of rainwater tanks.

Cost: The cost of rainwater tanks should be made as low as possible. This could be supported by subsidies from the government or through tax incentives, similar to those used to promote energy efficiency.

Demonstration: Rainwater harvesting demonstration sites should be developed so that these can be visited and inspected by the general public as well as building designers and building owners. Centrally located government offices as well as schools and clinics would be suitable as demonstration sites.

Municipal by-laws: Simple municipal bylaws which support the adoption of rainwater harvesting systems should be developed. These should be made available to municipalities wishing to promulgate rainwater harvesting bylaws.

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Building regulations: Building regulations should be drafted to cover water efficiency and rainwater harvesting.

These could be used to make rainwater harvesting systems a legislated requirement in buildings.

References • • • • •

• •

Department of Environmental Affairs. (2011). World Cup Legacy Report. Accessed from https://www. environment.gov.za/sites/default/files/docs/water.pdf Department of Water Affairs and Sanitation. (2012). Overview of the SA Water Sector. Accessed from https://www.dwa.gov.za/Documents/ ICRAF & UNEP. (2005). Potential for Rainwater Harvesting in Ten African Cities: A GIS Overview. Accessed from www.unep.org/pdf/RWH-AFRICAN-CITIES.pdf Statssa. (2014). Households experience increased access to piped water but are less satisfied with the service. Accessed from http://www.statssa.gov.za/?p=2788 Wensley, A., & Mackintosh, G. (2015). Water Risks in South Africa, with a particular focus on the “Business Health” of Municipal Water Services. DHI-SA 2015 Annual Conference. Accessed from https://www.dwa. gov.za/ UNEP. (2009).The United Nations Environment Programme (UNEP). A Handbook on Rainwater Harvesting in the Caribbean. Prepared by The Caribbean Environmental Health Institute.

UNEP. (2014). Keeping Track of Adaptation Actions in Africa, Nairobi.

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In times of increasing global water scarcity, water management is of increasing importance for the landscaping and agricultural sectors.

ZEOPLANT is a highly effective water retaining soil amendment consisting of fully natural mineral and organic components. Its unique features include high porosity, a very large active surface area, extremely good water retention, and high Cationic Exchange Capacity (CEC).

ZEOPLANT improves soil structure and increases the water holding capacity of soil so that the infiltration speed of irrigation water is reduced by up to 85%, Additional benefits include retaining nutrients in the root zone, the reduction of pH levels, improved CEC, and the formation of many new fine root hairs for healthier and faster plant growth.

ZEOPLANT combines the economical and ecological interests of project owners and developers in a sustainable form. Used with huge success on various major projects in U.A.E, Bahrain, Qatar, Saudi Arabia, Kuwait, Oman, South Africa, Australia, ZEOPLANT provides the solutions to sustainable and environmentally friendly landscaping and agriculture.

ZEOPLANT is easy to apply, and due to its mineral origin stays active in the soil indefinitely without needing reapplication. Ensuring sustainable water conservation for future generations.

ZEOPLANT is approved and certified by:

For more information please contact: Cape Contours Landscape Solutions Web: www.capecontours.co.za Email: info@capecontours.co.za Tel: +27 (0) 21 788 1202

Irrigation needs reduced by 50% Compost requirements in the soil mix reduced by 50% Savings of 50% on electricity for pumping of irrigation water Direct wear and tear savings on pumping units and irrigation equipment Reduction of storage cost for irrigation water (minimize / eliminate tanks).

Time and money saved on labour and maintenance The need for the ecologically harmful harvesting of peat moss for water retention completely eliminated Reduces carbon footprint

THE APPLICATIONS OF SISAL FIBRE-BASED MATERIALS IN THE BUILT ENVIRONMENT Opportunities For South Africa

Sihle Dlungwana1, Joe Mapiravana2, Naa Lamkai Ampofo-Anti3 and Nozonke Dumani4

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he building sector represented the largest uptake globally of natural fibre reinforced composites (NFRCs) in 2005 (Sharma et al, 2007). As the sector which consumes about 50% of all raw materials extracted from the Earth’s crust annually (Koroneos and Dompros, 2007), the major reason for this trend is a growing realisation that a radical shift in feedstock – from non-renewable to renewable materials – is needed if the building sector is to continue to deliver much needed physical infrastructure for the benefit of current and future generations.

Replacing conventional building materials with NFRCs can yield a range of environmental and economic benefits.

The environmental advantages, which are generalizable across NFRCs, include lower environmental impacts of reinforcing fibre production (Joshi et al, 2004), and sequestration of carbon dioxide from the atmosphere during the crop cultivation stage. Furthermore, in many instances, the initial cost and the maintenance of the NFRC have been shown to be lower (Umair, 2006). However, production of NFRCs is not environmentally neutral. As compared to conventional building materials, a major limitation shared by all NFRCs is the tendency to have a shorter service life (lower durability) – this aspect has been the subject of much research and development (R&D) since the 1980s (Berhane, 1987; Canovas, 1992; RD Toledo Filho et al, 2009; FA Silva et al, 2010)Furthermore, the agricultural input needs, which typically determine environmental performance, differ from one natural fibre to the next, thus a case by case examination of each natural fibre from a life cycle perspective is warranted. A range of natural fibres are currently the focus of R&D around the world with a view to use them in structural, semi-structural and non-structural building and construction applications. They

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include the bast fibres - flax, hemp, jute, kenaf and sisal, a leaf fibre. Table 1 provides a comparison of the performance properties of some natural and man-made fibres. This chapter explores the potential building and construction applications of sisal, a leaf fibre which is currently the subject of R&D at CSIR Built Environment. As compared to the popular bast fibres, sisal fibres are obtained from the Agave Sisalana plant which has lower input needs, is able to resist drought and thrives on marginal land which is unsuitable for growing other crops.

The sections which follow present brief overviews of NFRCs and the Agave Sisalana plant. This is followed by an in-depth review of the mechanical properties and the challenges of developing sisal fibre reinforced cementitious composites that are fit for long-life building applications. Thereafter, the potential environmental performance of sisal fibres is explored through a comparative life cycle assessment study. Finally, the opportunities for developing a strong sisal sector in South Africa; and the potential social and economic benefits of substituting conventional building materials with NFRCs are identified and discussed.

Background on natural fibre reinforced composites A composite material is created when two or more materials are combined on a macroscopic scale to form a third useful material. The key advantage of a composite material over a homogenous material is that it usually exhibits the best qualities of the constituent materials plus qualities that the constituents do not possess. The properties that can generally be improved by creating a composite material include strength, stiffness, reduction in weight and resistance to fatigue. Composite materials can be divided into four categories (Jones, 1999), namely:

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Table 1: Comparative properties of selected natural and man-made fibres •

Fibrous composite materials that consist of reinforcement (fibres) in a matrix (binder) • Laminated composite materials that consist of layers of materials • Particulate composite materials that are composed of particles in a matrix; and • Combinations of some or all of the first groups

The subject matter of this chapter is a sub-category of fibrous composite materials known as natural fibre reinforced composites. Therefore, the other three categories will not be discussed further from this point onwards.

The use of natural fibre reinforced composites in construction is not new. Although the precise date for commencement of usage is unknown, earth (the matrix) with straw (the reinforcement) has been used in building construction on every continent and in every age including the present. Known variously as “cob”,

“wattle-and-daub” and “adobe”, this “ancient” NFRC remained the norm until reduced in importance and largely replaced in the postIndustrial Revolution era by today’s major building materials such as steel, clay brick and concrete.

The development and commercialisation of modern fibre-reinforced composites began in the first decade of the 20th Century with cellulose fibre in phenolics, later extending to urea and melamine (Mohanty et al, 2000). Other than Henry Ford’s “biological car” of 1941, the composites industry devoted most of the 20th Century to developing synthetic reinforcing fibres, starting with glass fibre (1937), through carbon fibre (1960s) and finally to aramid fibre (1970s). However, from the late 1980s, the introduction of words such as “sustainable” and “green” into the lexicon of the building industry has sparked an interest to develop and reintroduce natural fibre reinforced composites as major building materials. This is because as compared to

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man-made reinforcing fibres, natural fibres (FA Silva et al, 2010): • Are cheaper and readily available; • Require a lower degree of industrialisation • for processing in comparison to an equivalent weight of the most common man-made fibres such as steel fibres; • Require lower levels of processing energy as compared to all other fibre types commonly used to produce fibre reinforced concrete (FRC); • Can be used as reinforcement in structural and semi-structural building elements including structural panels, beams and columns; • Can be used to produce impermeable building materials that are suitable for building envelope applications, for example, roof covering.

From the foregoing, NFRCs are novel building materials in the 21st Century. Therefore, data relating to the in-situ performance are lacking. This makes it difficult to demonstrate to potential specifiers the performance of natural fibre reinforced composites as compared to well-known composite building materials such as ordinary reinforced concrete (ORC) or glass fibre reinforced concrete (GFRC). In particular, the key research questions for which potential building industry specifiers and users may need answers are the following: • What are the mechanical properties of natural fibre reinforced composites and are they strong enough to replace common building materials such as ORC? • Given that natural materials are subject to organic decay, how does the durability profile or service life of a natural fibre reinforced composite compare to that of a steel or glass fibre reinforced composite?

• What, if any, are the environmental gains to be made by using natural fibres

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such as sisal fibres as the reinforcement in concrete in lieu of tried and tested reinforcing fibres such as steel or glass?

• The sections below provide answers to these three key questions.

Sisal Sisal fibre is a suitable reinforcement for use in NFRCs on account of its low cost, low density, high specific strength and modulus, no health risk, easy availability in some countries and renewability (Yan, L et al, 2000).

In recent years, there has been an increasing interest in finding new applications for sisal fibres that are traditionally used for making ropes, mats, carpets, fancy articles and others (Yan, L et al, 2000).

Sisal fibre is one of the most widely used natural fibres and the sisal plant (Agave sisalana) is very easily cultivated (Yan, L et al, 2000). It has a short renewal times and grows in the edges of field and railways tracks. Nearly 4.5.miIlion tons of sisal fibre are produced every year throughout the world. Sisal fibre is a hard fibre extracted

Figure 1: Agave Sisalana plant

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from the leaves of the sisal plant. Though native to tropical and sub-tropical North and South America, sisal plant (Figure 1) is now widely grown in tropical countries of Africa, the West Indies and the Far East (Yan, L et al, 2000). This chapter focuses on the prospects of the sisal plant fibres.

Mechanical properties of cement-based natural fibre reinforced composites Theoretical models of fibre reinforcement Fibrous materials have been used to strengthen and stiffen brittle matrices such as earth and concrete since prehistoric times. It is however only in the last fifty years that the principles of fibre reinforcement have been interpreted from a scientific perspective.

Two theoretical models have emerged – reinforcement theory, based on strength of materials, and fracture toughening theory, based on fracture mechanics. Both theories are commonly invoked to explain the mechanical behaviour of fibre reinforced composites.

Reinforcement theory Reinforcement theory emphasises the importance of fibre/matrix bond and anchorage; and the requirement for strong fibres. The theory also suggests that: • The fibres must span over cracks that may develop in the matrix; • A significant amount of matrix damage and or failure would occur in the absence of the fibres; and • It is the fibres that conduct forces applied to the composite material.

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The necessary conditions for fibres to act as reinforcement are fundamentally that on the one hand, the strength and stiffness of fibres need to be greater than those of the matrix – this relationship is expressed mathematically in Box 1. On the other hand, the ability of the matrix to withstand strain (loading) needs to be greater than that of the fibres. Sisal fibre cementitious matrix composites meet these necessary conditions.

Thus, from reinforcement theory, to achieve strengthening, strong bonding must exist between the matrix and fibre reinforcement due to three effects: a high fibre/matrix bond strength i.e. adhesion strength from adhesive forces between sufficiently long fibres and the matrix; the shape (morphology), aspect ratio and shear strength caused by fitting (tying) in surface roughness and friction strength, which is observed after failure of the other two forces.

Fracture toughening theory Fracture toughening theory emphasises energy absorption and requires the composite to be constituted in such a manner that fibre volume fraction is adequate. According to fracture theory, the goal of fibre reinforcement is to maintain matrix integrity. By contrast to reinforcement theory, the matrix is regarded as the forces conductor. The R&D of a natural fibre reinforced thin concrete slab and panel skin by the CSIR Built Environment will make use of concepts from the two underpinning theories in developing the materials.

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Figure 2(a) and 2(b): Longitudinal appearances of sisal fibre bundles. The striated depressions in sisal fibres provide anchorage to the reinforced matrix From fracture toughening theory, there is need for high composite fracture toughness or energy absorption before failure. From fracture toughening theory, a strong and tough matrix is necessary for high energy absorption. Beyond some fibre content, strength will decrease as toughness increases. It is therefore important to establish optimum fibre content. As

illustrated in Figure 3, adding a mere 3% by weight of sisal fibre content to ordinary cement and concrete building materials will substantially increase their resistance to fracture by up to 50 times.

The macroscopic fracture strength (ﾏデ ) of a specimen under uniform stress is given by the Griffith equation set out in Box 2.

The fibre count is directly related to the statistical probability of cracks encountering and interacting with the fibres in the composite matrix that increase

Figure 3: Effect of sisal fibre content on fracture toughness of a high performance cement blend

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fracture energy and control fracture failure of the reinforced concrete matrix. The fibre specific surface is directly related to the amount of energy that is absorbed in encounters between cracks and fibres. Fibre count and specific surface are functions of fibre volume, geometry (equivalent fibre diameter and fibre length), specific gravity and fibre dosage rate. The mechanical properties of the fibres will determine the amount of energy the fibres can absorb before rupture and through crack bridging.

Fibre surface morphology influences fibre/ matrix anchorage and bonding. Fibre surface properties influence fibre/concrete matrix energy absorbing mechanisms that are responsible for matrix toughening, including fibre pull-out, fibre rupture, fibre crack bridging, fibre/matrix interfacial debonding and matrix cracking.

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NB. Equivalent compressive strength values are 6 to 8 times the 3-point bend strength.

Thus for 2% by weight of sisal fibre content, the compressive strength would be 120 to 160 MPa, which is much higher than that required of a normal building brick, that is, 7 MPa. Therefore, the incorporation of sisal fibres in cementitious building materials has dual benefits – it significantly improves both fracture toughness and strength.

Major development and application challenges of cement-based natural fibre composites Major challenges associated with the application of natural fibres (including sisal) in cement matrix composites are: • Durability, that is, the ability to withstand environmental degradation in the highly

Figure 4: Effect of sisal fibre content on 3-point bend strength of a high performance cement blend

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alkaline environment of the cement matrix; • The need to ensure homogeneity during composite manufacturing to limit variability of composite properties, especially at high fibre contents; • The need to optimise strength and toughness, which may have an inverse relationship.

Durability of cement-based natural fibre reinforced composites Given the long life of buildings, which is typically estimated to be fifty years and more, durability performance of fibre reinforced concrete (FRC) as compared to ordinary reinforced concrete (ORC) has been the subject of much research. In general, the FRCs which rely on steel, glass or synthetic fibres as reinforcement are more durable than ORC. However, because plants are naturally subject to organic decay, durability performance is the “Achilles heel” in the life cycle of NFRCs. Berhane (1987) concluded that cement-based roof coverings reinforced with sisal fibres had a very short service life, especially in hot, humid climates. This is because the calcium hydroxide (CH) in ordinary Portland cement (OPC) creates an alkaline environment (RD Toledo Filho et al, 1999; RD Toledo Filho et al, 2009; FA Silva et al, 2010) which in turn sets up two mechanisms for the deterioration of the sisal fibres, namely: • The natural links between sisal fibre cells are destroyed, leading to a loss of reinforcing capacity; and • There is crystallisation of lime in the walls of individual sisal fibres resulting in a loss of fibre flexibility and strength.

A number of durability enhancing strategies for sisal fibres have been devised and empirically tested over the last three decades. Gram (1983) and Canovas et al

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(1992) attempted a wide range of sisal fibre pre-treatment and impregnation techniques. Some of the techniques were able to slow down the fibre embrittlement process. However, none of these efforts were able to completely stop the degradation of sisal fibres in the alkaline environment of 100%OPC matrix.

Gram (1983) reported that the fundamental problem of alkalinity could be resolved - that is, a calcium hydroxidefree (CH-free) matrix could be created by replacing a fraction of the OPC with high alumina cement or a natural pozzolana.

RD Toledo Filho et al (2009) investigated Gram’s approach by comparing two sisal fibre reinforced concrete specimens – one constituted as sisal fibre in 100% OPC matrix, and the other constituted as sisal fibre in 50% OPC/ 50% calcined clay matrix. They found that partial replacement of OPC by calcined clay indeed resulted in a CH-free matrix that created an enabling environment for durability of the sisal fire reinforced concrete material. In 2010 the same group of researchers compared the durability performance of a CH-free composite (sisal fibre in 50% OPC/ 50% pozzolana matrix) to a standard composite (sisal fibre in 100% OPC matrix). The researchers found that as compared to the standard composite, the CH-free composite had superior bending strength (3.8 times higher) and toughness (42.4 times higher). They concluded that durability is no longer a barrier to the use of sisal fibre reinforced concrete products in building applications, provided that the matrix is CH-free (RD Toledo Filho et al, 2010).

Potential environmental performance of sisal fibres replacing steel fibres as reinforcement in concrete Overview of reinforced concrete The use of plain concrete as a building material dates back at least 2000 years to the

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period of the Roman Empire. The inclusion of steel – as mesh or bars/rods – to form ordinary reinforced concrete (ORC) was developed and patented by the French between 1840 and 1900 (Concrete Construction, 1961).

Fibre reinforced concrete (FRC), which is concrete with uniformly dispersed fibres acting as reinforcement instead of steel mesh or rebar (Sonasath, 2014), is a much more recent variation of reinforced concrete which emerged in the 1960s (Zollo, 1997).

The key benefits of FRCs as compared to ORC are that (Sonasath, 2014): • The fibres do not require minimum cover as they do not rust or corrode • FRCs can be spray applied and are therefore easy to place and less labour intensive • FRCs can be used to make thinner, lighter and tougher reinforced concrete products, thus they can be used in novel applications for which ORC is not suitable However, not all benefits can be generalised.

Steel, glass and synthetic fibre reinforced concretes are generally more durable than ORC but also more expensive. As compared to ORC, natural fibre reinforced concrete (NFRC) is cheaper, but the durability performance and service life requirements are not well established.

According to the terminology adopted by the American Concrete Institute, there are four categories of FRCs, namely (Zollo, 1997): • Steel fibre reinforced concrete (SFRC); • Glass fibre reinforced concrete (GFRC); • Synthetic fibre reinforced concrete (SNFRC); and • Natural fibre reinforced concrete (NFRC) In terms of environmental performance, the available literature suggests that the life cycle energy use and emissions from the production of glass and synthetic fibres are

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significantly higher than those associated with natural fibre production. For example, glass fibre production and polypropylene fibre production may require respectively twelve times more and twenty times more energy than China reed fibre production and correspondingly the emissions are higher. These observations are valid across most natural fibres (Joshi et al, 2004). There is a dearth of literature that could facilitate a similar comparison of steel fibres and natural fibres. The purpose of this section is to use Life Cycle Assessment (LCA) to investigate the environmental gains to be made, if any, of sisal fibres replacing steel fibres as reinforcement in concrete in the South African context.

Methodology LCA is the most appropriate approach for evaluating the environmental impacts associated with a product by quantifying the resources consumed (energy, materials, water, land) and the emissions to the environment (air, water and soil) at all stages of the product life cycle from cradle-to-grave.

According to the international standards ISO/SANS 14040: 2006 Environmental Management Life Cycle Assessment – principles and framework, an LCA study entails four mandatory steps, namely: • Goal and scope definition: stating the reason for the study; and defining the scope of the product (technical) system to be investigated.

• Life cycle inventory (LCI) analysis: compiling and quantifying inputs (resources consumed) and outputs (emissions) within a system boundary to meet the goals of the study.

• Life cycle impact assessment (LCIA): interpreting the inputs and outputs to understand the contributions of the investigated product to environmental problems such as non-renewable energy

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Figure 5: Generic life cycle stages of the reinforcing fibres indicating extent of cradle-to-gate analysis, Author depletion, global warming or ozone depletion • Life cycle interpretation: evaluating the findings of the LCI and LCIA steps in relation to the stated goal and scope to reach conclusions and make recommendations.

The LCA software tool SimaPro version 8.1 was used to compile the life cycle inventories for steel fibre production and sisal fibre production; and to perform the LCIA. It is assumed that both types of fibre are produced in South Africa. Due to the difficulty in finding South Africa-specific LCI data, European industry average LCI data, obtained from SimaPro’s complementary ecoinvent Database (version 3), were “localised” to fit the study context. Additional LCI data were sourced from published literature, or were calculated or estimated.

Although SimaPro offers a range of LCIA methods to choose from, all are underpinned

by European or North American data and technology. The CML Baseline method (European, 2013 version) was chosen as it covers the impact categories of interest to this study in a comprehensive manner.

Goal and scope definition This screening life cycle assessment study compares steel and sisal fibres intended for use as reinforcement in concrete. The results

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are intended to showcase the environmental performance of NFRCs to potential South African “green” building material specifiers.

It is assumed: • That the steel fibres will be used as reinforcement in 100% OPC matrix • That the sisal fibres will be used as reinforcement in 50% OPC/ 50% calcined clay matrix • That a comparison of 100%OPC matrix to 50%OPC/ 50%pozzolana matrix is not necessary because previous research results obtained by RD Toledo Filho et al (2010) and Ampofo-Anti (2013) already confirm that the substitution of the former with the latter matrix will result in at least 40% savings in the total matrix production energy and a corresponding reduction in the contribution to global warming and other energy-related emissions.

The scope of the LCA study, as indicated in Figure 5, is limited to a cradle-to-gate comparison of the production of 1kg steel fibres versus production of 1kg sisal fibres.

Steel is an energy intensive material – in 2006 the production of steel-based products destined for use in the South African building and construction sector accounted for about 4% of total national GHG emissions (CIDB, 2007). From an environmental perspective, the primary motivation for substituting steel fibres with sisal fibres as reinforcement in

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concrete is to reduce the contribution of reinforcing materials to energy use and the associated environmental emissions.

The two types of reinforcing fibre are therefore compared on the basis of production energy; and the contribution of the associated environmental emissions to global warming potential (GWP), stratospheric ozone depletion potential (ODP), photo-chemical oxidant creation potential (POCP), acidification potential (AP) and eutrophication potential (EP).

Life cycle inventory Micro steel fibre production According to Stengel and Schießl (2008) the production of high strength micro steel fibres entails eight steps, namely: • Electric steel production – this is the reprocessing of scrap metal in the electric arc furnace (EAF) in order to produce semi-finished steel products • Hot rolling – at the hot rolling mill, the semi-finished steel products are reheated until red hot (1200°C), and then passed backwards and forwards at high pressure through steel drums (rolls) to

•

•

•

•

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produce hot rolled wire to the desired diameter and length Descaling – when hot rolled wire cools down a hard brittle surface oxide layer known as scale forms which must be removed before the wire can be drawn to smaller diameters. The conventional descaling method is to bend the wire in different directions in order to loosen the scale which is then removed by brushing.

Dry wire drawing – this is performed to pull hot rolled wire down to a diameter of approximately 1.8mm. Mostly calcium and sodium soaps are used as a dry lubricant. Since friction can cause temperatures as high as 400°C, the drawing dies are cooled with water and the wire with compressed air.

Wet wire drawing – this process enables the wire diameter to be reduced to its final value of approximately 0.175mm.

The wire and the machinery are cooled with a drawing liquid consisting of an aqueous emulsion of vegetable oils and fats (lubricant) Tempering – the wire drawing process enables tensile strength as high as

Figure 6: Process stages for the production of high strength micro steel fibres including system boundary (dashed lines) Adapted from Stengel and Steißel, 2008

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4 000 N/mm2 to be achieved. However, ductility is lost. To restore ductility, the wire is tempered in a continuous feed method by heating it to 500°C and cooling it in water or oil. Tempering is performed under an inert gas blanket to avoid unwanted oxidation reactions.

• Steel cord wire strand fabrication - Single steel wires are laid in strands by twisting around a common central axis. Strand is easier to handle than wire thus enabling a larger output in steel fibre production in the last stage of manufacture.

• Cutting to length - In this last sub-process, the high strength steel wire strand is cut to length producing individual fibres having the required length.

It is assumed that the steel fibres are produced in South Africa. Figure 6 depicts the process steps for the production of micro fibre steel; and the system boundary applied in this study.

Sisal fibre production It is assumed that the sisal fibres are obtained from the leaves of an Agave Sisalana crop which is cultivated under rain-fed conditions in Kwazulu Natal, South Africa.

The following typical production scenario for long, brushed sisal fibres has been taken into account, namely: • Seed for sowing – no seed for sowing is taken into account because the old Agave plants produce bulbils or suckers (young plants) before they die • Nurturing of bulbils or suckers – the young plants are kept in the nursery for twelve to eighteen months. The inputs are rainwater and partially rotted Agave Sisalana leaves • Tillage of field – field preparation is by means of traditional mouldboard ploughing • Agricultural inputs - the only input accounted for is potassium chloride

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•

• •

•

•

•

fertiliser at the rate of 50kg/ha. Nitrogen and phosphorous fertilisers and pesticides are not a prerequisite for cultivation of Agave Sisalana. The Agave Sisalana thrives in drought conditions therefore irrigation water is not needed / a rainfed system is assumed Inputs from nature – during the growth phase of Agave Sisalana, carbon dioxide is sequestered from the atmosphere at the rate of about 1.8kgCO2/kg dry sisal fibre. Furthermore, renewable energy is embodied in the biomass as a result of photosynthesis Planting of crop – Agave Sisalana is planted manually Harvesting – harvesting of the leaves is done manually and takes place every six to nine months. An Agave plant can produce a total of three hundred leaves throughout the productive period which is seven to eight years Decortication – sisal fibres are extracted from the Agave leaves by means of decortication, a process in which the leaves are crushed between rollers and then mechanically scrapped to extract the fibres. Decortication requires an energy input of about 2GJ/tonne of fibre.

It is also a wet process, requiring about 100m3/tonne fibre.

Drying of fibres – after extraction, the sisal fibres are sun dried. The average yield of dried fibre is about 1tonne/ha.

It is estimated that dried fibres represent only about 4% of the total weight of an Agave leaf Brushing or combing of fibres - the dried fibres are mechanically double brushed. Sisal fibre brushing requires about 0.048GJ/tonne of fibre. When a process produces more than one product, it is necessary to use allocation methodology to partition the environmental consequences over

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Figure 7: Process stages for the production of sisal fibres including system boundary (dashed lines) product of interest and the co-products.

The brushing process produces three grades of sisal fibre – short, medium and long. Long fibres are preferred for use as reinforcement. In this study, the Agave crop is assumed to be cultivated for the sole purpose of producing long fibres, therefore no allocation is carried out.

Figure 7 depicts the process steps for the production of long, brushed sisal fibres for use as reinforcement in FRC. The system boundary applied in this study is indicated in dotted lines.

Results and discussion The results of the comparative study, set out in Table 2 above and depicted graphically in Figure D below, suggest that as compared to sisal fibre production, steel fibre production: • Requires about four times as much energy input; • Contributes about four times as much to greenhouse gas emissions (GWP); • Contributes about four times as much to ground level ozone formation (POCP), the emission of air pollutants which

Table 2: results for comparison of micro steel fibre production to sisal fibre production

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have a wide range of negative effects on ecosystems (AP); and the emission of air pollutants which contribute to poor water quality and biodiversity loss (EP).

• Contributes about five times as much to stratospheric ozone depletion

life cycle energy use and corresponding emissions of the sisal fibre composite could turn out to be higher than those of the steel fibre composite, thus the superior performance demonstrated in this study would be lost. Such a whole life comparison could however not be investigated in the When the results of the present study are present study due to a lack of service life compared with the findings of Joshi et al data for both steel fibre reinforced concrete (2004), a preliminary ranking of the four and sisal fibre reinforced concrete. fibres types used for production of FRCs emerges as demonstrated in Table 3. The Opportunities for sisal fibre in South environmental performance of the natural Africa’s building and construction sector fibres is significantly better than that of the The mechanical, environmental and physical man-made fibres. It is, however, noted that properties of sisal fibre as characterised the superior performance of natural fibres in the previous sections above creates illustrated in Table 2 and Figure 8 is informed suitability for the sisal fibre application in by cradle-to-gate study results which provide a vast array of building and construction an incomplete picture of the environmental sector products. The building and performance of an assessed product. construction industry comprises one of the Given the long service life of buildings, largest users of composite materials due to the comparison of materials destined for reduced installation, handling, repair and life building applications should be informed cycle costs, as well as improved corrosion by whole life cycle “cradle-to-grave” analysis. resistance (Swanepoel, 2010). Sisal fibre is an For example, should the use/maintenance important component that features strongly stage of a sisal fibre reinforced concrete in natural fibre reinforced composite product require significantly higher energy (NFRC) products. Table 3 lists examples of inputs as compared to the equivalent steel natural fibre reinforced plastics (NFRPs) fibre reinforced concrete product, the total that are used in interiors/ internal finishes

Figure 8: Comparison of micro steel fibre production to sisal fibre production

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Table 3: Examples of existing and potential NFRP applications worldwide Adapted from Swanepoel, (2010). and the building and construction sectors worldwide (Swanepoel, 2010). Examples of cement-based natural fibre reinforced composites, that are the subject matter of this paper, are listed in Table 4.

The composites sector currently comprises a significant number of small business opportunities as evidenced in India, China, USA and other countries (Swanepoel, 2010).

In the USA, the birthplace of NFRPs, this sector has grown by 10% per annum over the past few years. Whilst the list of products in Table 3 was compiled based on the global market, Swanepoel argues that there is a potential to grow the South African NFRP market, including through the replacement of existing products.

South Africa has been described as being well-positioned to develop competencies in light weight structures and materials, which include natural fibre composites. The local industry is nevertheless in its early days, with only a small number of businesses that have tried their hand at NPC products (Swanepoel, 2010). However, there is potential to develop a good sisal industry given South Africa’s climatic conditions and overall global demand for NFRCs, and the fact that South Africa imports a substantial amount of natural fibres.

The low production levels for nonwood, natural fibres in South Africa were demonstrated by Swanepoel (2010). Only kenaf and sisal had traceable production sources in some provinces, even these were on a very small scale. This can be seen as the opportunity to scale up supply of sisal, which can arguably be cultivated in all the country’s provinces, especially in the tropical and subtropical regions where such conditions favour the plant. Sisal has been cultivated successfully in Limpopo, North West and KwaZulu Natal.

The envisaged sisal industry promises to have a positive development impact in the building and construction sector and the larger South African economy. The perceived economic benefits are rural development, job creation, SME development and skills development (Swanepoel, 2010). In order to develop the sisal industry into a strong component of the economy, a development strategy should be driven and supported by the relevant government department or agency in collaboration with relevant private sector stakeholders.

Summary and conclusions The very high fracture toughness and strength values obtained by incorporation of 1% – 3% volume fraction of sisal fibres in a high

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Table 4: Examples of existing applications of cement-based natural fibre reinforced composites performance cement blend matrix clearly indicates that sisal fibres are viable reinforcement for cement based building materials such as roofing tiles or sheets and external skins of structural insulated panels. Technology demonstrators are being developed by the CSIR. Both reinforcement theory, based on strength of materials, and fracture toughening theory, based on fracture mechanics, may be invoked to explain the fracture behaviour of sisal fibre cement matrix composites.

The results of the LCA study demonstrate the superior environmental performance of sisal as compared to steel reinforcing fibres.

Currently, steel fibres are being used in South Africa as the sole reinforcement or combined with traditional reinforcement in a number of building-related structural applications which include pre-cast elements and insitu cast flooring (Arcelor Mittal, 2015; Fibsol, 2015). The LCA results obtained here demonstrate that substitution of steel with sisal fibres in these local applications could potentially yield the following environmental benefits: • Reinforcement – about 4 times less energy would be required for production of reinforcing materials (Table 2); and correspondingly, about 4 times less contribution would be made to global warming and a range of other environmental problems.

• Matrix - about 2 times less energy would be required for production of matrix

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constituents; and correspondingly, about 2 times less contribution would be made to global warming and a range of other environmental problems. This is because substitution of steel with sisal fibres implies a change from 100% OPC matrix to 50%OPC / 50% pozzolana matrix.

The envisaged sisal industry promises to have a positive development impact in the building and construction sector and the larger South African economy. The potential benefits include: • Socio-economic benefits - rural development, job creation, SME development, skills development and development of new “green” materials • Environmental benefits – the substitution of a range of common building materials with “green” sisal fibre reinforced composites could reduce embodied energy and reduce carbon footprints across the building sector.

However, in order to develop the sisal industry into a strong component of the economy, a development strategy would need to be driven and supported at the highest level by the relevant government department, such as the Department of Trade and Industry or the Department of Science and Technology, or an agency, in collaboration with private sector stakeholders.

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References • • • • • • • • • • • • • • • • • • • • • • • • • •

Ampofo-Anti, N.L., 2013. “Screening Life Cycle Assessment study of a sisal fibre reinforced micro-concrete structural insulated panel.” In proceedings of the International Conference on Composites and Bio-composites, Durban University of Technology, December 2013.

Arcelor Mittal. 2015. – Superior steel fibre technology for your projects. [Online] Available at: http:// dsarcelormittal.com/wiresolutions/steelfibres/applications/language/EN [Downloaded: (date)].

Berhane, Z. 1987. “Durability of mortar roofing sheets reinforced with natural fibres.” In proceedings of Symposium on building materials for low-income housing, Bangkok, Thailand. 20-26 January 1987, pp321-327.

Brouwer, W.D.R., 2001. Natural fibre composites in structural components: alternative applications for sisal? In: Alternative applications for sisal and Henequen. Rome: Common Fund for Commodities –FAO. Technical paper no.14 Canovas, M.F., Kawiche, G.M., Shelva, N.H. 1992. “New economical solutions for improvement of durability of Portland cement mortars reinforced with sisal.” Materials and Structures, 25(1992): 417-422.

Concrete Construction, 1961. The development of reinforced concrete. [Online] Available at: http:// www.concreteconstruction.net/development/the-development-of-reinforced-concrete.aspx [Downloaded: (date)] CIDB, 2007. The building and construction materials sector – challenges and opportunities. [Online] Available at: http://www.cidb.org.za/knowledge/publications/default.aspx [Accessed 15 July 2015].

De Andrade Silva, F., Toledo Filho, R.D., De Almeida Melo Filho and De Moraes Rego Fairbairn, E. 2010.

“Physical and mechanical properties of durable sisal fibre-cement composites.” Construction and Building Materials 24(2010) 777-785.

FAO, 2009. Natural fibres. [Online] Available at: http://www.naturalfibres2009.org/en/fibres/hemp.html, [Accessed: 29 July 2015].

Fibsol, 2015. Fibre reinforcing solutions. [Online] Available at: http://fibsol.co.za/ [Accessed on 20 July 2015].

Gram, H.E. 1983. Durability of natural fibres in concrete. Swedish Cement and Concrete Research Institute. [Online] Available at: https://books.google.co.za/books/about/Durability_of_Natural_Fibres_ in_Concrete.html?id=tAuQNQAACAAJ&redir_esc=y [Accessed on 02 July 2015] Jones, R.M. 1999. Mechanics of composites materials. Second Edition. USA: Taylor and Francis,. ISBN 1-56032-712-X. Joshi, S.V., Drzal, L.T., Mohanty, A.K.and Arora, S. 2004. “Are natural fibre composites superior to glass fibre reinforced composites?” Composites: Part A 35 (2004): 371-376.

Koroneos, C. and Dompros, A. 2007. “Environmental assessment of brick production in Greece.” Building and Environment. 42(2007): 2114-2123.

Mohanty, A.K., Misra, M. and Hinrichsen, G. 2000. “Biofibres, biodegradable polymers and biocomposites: an overview.” Macromolecular Materials Engineering, 276-277(1): 1-24.

Prasannakumar, M and Venkatesh, A, 2014. Fibre reinforced concrete. [Online] Available at: http://www. slideshare.net/VenkateshCa/fibre-reinforced-concrete, [Accessed on 30 July 2015].

Sharma, R.S., Raghupathy, V.P., Sashank Rao, S. and Shubhanga, P. 2007. Review of recent trends and developments in biocomposites. [Online] Available at: www.sashankrao.webs.com/REVIEW%20OF%20 RECENT%20TRENDS%20 [Accessed on 20 July 2015].

Sonasath, M., 2014. Application of fibre reinforced concrete (FRC). [Online] Available at: http://www. slideshare.net/mustafasonasath/fibre-reinforced-concrete-40540346 [Accessed on 07 July 2015].

Stengel, T and Schießl, P. 2008. “Sustainable construction with UHPC – from life cycle inventory data collection to environmental assessment.” In proceedings of the second international symposium on UHPC, Kassel, Germany, 05-07 March, 2008, pp. 461-468.

Swanepoel, J., 2010. The potential for a biocomposites industry in South Africa. Industrial Development Corporation (IDC) Department of Research and Information, November 2010.

Toledo Filho, R.D., De Andrade Silva, F., De Almeida Melo Filho and De Moraes Rego Fairbairn, E. 2009.

“Durability of compression moulded sisal fibre reinforced mortar laminates.” Construction and Building Materials 23(2009): 2409-2420.

Toledo Filho, R.D., Joseph, K., Ghavami, K. and England, G.L. 1999. The use of sisal fibre as reinforcement in cement based composites. [Online] available at: http://www.agriambi.com.br/revista/v3n2/245.pdf [Accessed on 02 July 2015].

Umair, S. 2006. Environmental impacts of fibre composite materials – study on life cycle assessment of materials used for ship superstructure. Royal Institute of Technology, Stockholm, 2006. [Online] Available at: www.diva-portal.org/smash/get/diva2:453762/FULLTEXT01.pdf [Accessed on 20 July 2015].

Zollo, R.F. 1997. “Fibre reinforced concrete: an overview after 30 years of development.” Cement and Concrete Composites, 1997(107-122).

Yan, L., Yiu-Wing, M., Lin Y., 2000. “Sisal fibre and its composites: a review of recent developments.”

Composites Science and Technology 60: 2037-2055.

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T

he comparative thermal performance of different wall construction types has been comprehensively tested and modelled. Extensive research supports the case for walls with high thermal mass and various levels of thermal insulation being more energy efficient than insulated lightweight walling as applied to Alternate Building Technologies, including Light Steel Frame in accordance with SANS 517.

Alternate Building Technologies use the higher wall R-value of insulated lightweight walling systems to define energy efficiency and reference research that presents lightweight walling systems as being more energy efficient than walls with thermal mass.

This chapter references the findings of both empirical research undertaken at the University of Newcastle, Australia, Priority Research Centre for Energy and thermal modelling studies undertaken in both South Africa and Australia using ASHRAE compliant modelling software (DesignBuilder EnergyPlus and Visual DOE), to argue that conventional clay brick construction (220mm solid double brick and 270mm cavity brick) in compliance with SANS 10 400 XA Building Regulations, and insulated cavity brick in compliance with SANS 204 Energy Efficiency Standards for masonry buildings, provide walling envelope options to different building typologies and occupancy, for achieving higher thermal performance and lower heating and cooling energy usage to that of insulated lightweight walling envelopes, SANS 204 compliant.

Chapter Content: This chapter investigates the thermal mass versus insulated lightweight technology argument. It considers correlations in the comparative findings from different research (empirical and modelling) into the thermal performance of walling envelopes that confirms the relationship between thermal

xx CLAY BRICK

mass and superior energy efficiency. It reports and interrogates the findings of a parametric software study and reviews computer-based calculation methods for simulating unsteady-state heat transfer through walling systems to identify which of the research findings referenced for and against walling envelopes with thermal mass is most representative of reality, most accurate, and could thus be used as a credible reference source to show how different wall construction types perform.

The chapter analyses the findings of a recent University of Pretoria study, “A Thermal Performance Comparison between Six Wall Construction Methods Frequently Used in South Africa” (Vosloo, Harris, Holm, van Rooyen and Rice 2015) and what the findings of that study mean in the context of South Africa’s regulatory framework for specifying walling envelopes for superior thermal efficiency and lowest heating and cooling energy outcomes.

Empirical Research Evidence and Correlations Ten years of empirical research and analysis of the thermal performance of different wall construction types at the University of Newcastle, Australia, Priority Research Centre for Energy, found at an early stage of that research that the wall R- value is not the all-important thermal performance property of a material and that there is no direct correlation between building performance and wall R-value alone ,“A Study of the Influence of Wall R Value on the Thermal Characteristics of Australian Housing” (Page, Moghtaderi, Sugo, Hands 2009)(15).

This is demonstrated in Table 1 below of a comparison of the energy usage for the 6 week period with wall R-value and where the consumption values were normalised against the Ins-CB (Insulated Cavity Brick) case.

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The four walling systems typical of The Ins-LW module (R1.69) module, Australian housing investigated included. despite having an R-value 14% higher than • Conventional Cavity Brick (CB): 110mm the Ins-CB (R1.48), used 117% more energy. external brickwork skin; 50mm air cavity; Even the Ins-BV (Insulated Brick Veneer) 110mm internal skin finished with 10mm module (R1.72) with an R-value 16% greater than the Ins-CB used 50% more energy this render. Research Evidence and Correlations Empirical Empirical Research Evidence and Correlations • Insulated Brick Veneer (Ins-BV): 110mm reflecting the contribution of the thermal Ten years of empirical research and analysis of the thermal performance of different wall Ten years obrickwork f empirical skin; research and air analysis of the thermal performance of dof ifferent wall wall. external 50mm cavity mass of the interior skin the external construction types at the University of Newcastle, Australia, Priority Research Centre for construction types and at the University of Newcastle, Australia, Priority Research Centre for with wall-wrap R1.5 bulk insulation Energy, found at an early stage of that research that the wall R-­‐ value is not the all-­‐ Energy, found at an early f that frame/ research that the Construction wall R-­‐ value is not the aand ll-­‐ Wall batts incorporated instage the opine important thermal performance property of a material and that there is Types no direct important thermal performance property of a material and that there is no direct Usage plasterboard cavity; 10 mmperformance plasterboard correlation between building and wEnergy all R-­‐value alone ,“A Study of the Influence correlation between building performance and wall R-­‐value alone ,“A Study of the Influence of Wall R Value on the Thermal Characteristics of Australian Housing” (Page, Moghtaderi, full total H energy for the interior. of Wall R Value on the Thermal Characteristics of The Australian ousing” usage (Page, findings Moghtaderi, Sugo, Hands Cavity 2009)(15).

(Ins-CB): 110mm 6 week period July- August 2008 in Figure 1 • Sugo, Insulated Brick Hands 2009)(15). external brickworkin skin; 50mm airocavity belowo(2009:10) (15), together the other This i s emonstrated able elow omparison he eenergy nergy usage sage or tthe he with 6 week eek This ddemonstrated in TTable 11 bbelow of f fixed aa ccomparison of f tthe uin ffor withis R1 rigid polystyrene insulation findings reported “A Study of6 w the Thermal period w ith w all R -­‐value a nd w here t he c onsumption v alues w ere n ormalised a gainst t he period with wall R-­‐value and where the consumption values were normalised against the to the interiorCavity masonry skin; 110mm Performance of Australian Housing”, Priority Ins-­‐CB ( Insulated B rick) c ase.

Ins-­‐CB (Insulated Cavity Brick) case. interior brickwork skin finished with Research Centre for Energy, University of The our cement walling alling ssystems ystems ypical oof f AAustralian ustralian hhousing ousing nvestigated included.

Newcastle, Australia (Page, Moghtaderi, 10mm render.ttypical The ffour w iinvestigated included.

-­‐ Conventional Cavity Brick (CB): 110mm external brickwork skin; 50mm air cavity; 110mm • -­‐ Conventional Cavity Brick (CB): 110mm external brickwork skin; 50mm air cavity; 110mm Insulated Lightweight construction Alterman, Hands 2012) (16) are considered internal sskin kin ffinished inished w with ith 110mm 0mm rrender. ender. internal (Ins-LW): polymer render over 7mm relevant in the South African context given -­‐-­‐ Insulated Insulated Brick Brick Veneer Veneer (Ins-­‐BV): (Ins-­‐BV): 110mm 110mm external external brickwork brickwork skin; skin; 50mm 50mm air air cavity cavity with with Fibro-cement sheeting; breathable that n the research was undertaken in a wall-­‐wrap aand nd RR1.5 1.5 bbulk ulk iinsulation nsulation bbatts atts iincorporated ncorporated iin the he ppine ine fframe/plasterboard rame/plasterboard ccavity; avity; wall-­‐wrap t moderate climatic zone with temperature membrane fixed onto pine stud frame; 10 m mm m pplasterboard lasterboard iinterior. nterior.

10 R1.5 bulk insulation in frame cavity; ranges comparable to those of South Africa’s Insulated Cavity Brick (Ins-­‐CB): 110mm external brickwork skin; 50mm air cavity with R1 -­‐-­‐ Insulated Cavity Brick (Ins-­‐CB): 110mm external brickwork skin; 50mm air cavity with R1 10mm plasterboard interior.

4.110mm interior rigid polystyrene insulation fixed to to the the interior interior Climatic masonry Zone skin; 110mm interior brickwork brickwork rigid polystyrene insulation fixed masonry skin; skin

f inished w ith 1 0mm c ement r ender.

As shown in Figure 1: skin finished with 10mm cement render. nsulated ightweight onstruction Ins-­‐LW): olymer ender ver 77lightweight mm FFibro-­‐cement ibro-­‐cement • The As -­‐-­‐shown, theLLightweight two alternative extreme cases ppolymer insulated (InsLW) walled IInsulated cconstruction ((Ins-­‐LW): rrender oover mm sheeting; b reathable m embrane f ixed o nto p ine s tud f rame; R 1.5 b ulk i nsulation in fframe rame relative sheeting; b reathable m embrane f ixed o nto p ine s tud f rame; R 1.5 b ulk i nsulation in of high thermal mass with no insulation building was the worst performer cavity; 110mm 0mm pplasterboard lasterboard iinterior. nterior. cavity; (Cavity Brick-CB), and insulated lightweight to all walling envelopes that contained

with no thermal mass (Ins-LW), – ncavity brick (Cavity (CB), and As sshown, hown, he ttwo wo aalternative lternative xtreme ccboth ases oof f hhigh igh tthermal thermal hermal m mmass ass wwith ith insulation As tthe eextreme ases ass no o insulation (Cavity insulated brick veneer (InsBV).

Adding required much higher energy consumption, Brick-­‐CB), a nd i nsulated l ightweight w ith n o t hermal m ass ( Ins-­‐LW), b oth r equired m uch Brick-­‐CB), and insulated lightweight with no thermal mass (Ins-­‐LW), both required much a skin of tthan external brick veneer and/ thehigher Ins-LW being marginallytthigher than CB m higher nergy onsumption, he IIns-­‐LW ns-­‐LW eing marginally arginally igher han CCB B in in tthis his pparticular articular eenergy cconsumption, he bbeing hhigher period. or reverse brick veneer to lightweight in period. this particular period.

walling envelopes improved energy Table 1 :

C omparison o f E nergy U sage ontrolled IInterior nterior Table 1: Comparison of Energy Usage –– CControlled Wall Wall

R-­‐Value R-­‐Value

Heating EEnergy nergy Heating

Cooling EEnergy nergy Cooling

Total EEnergy nergy Total

Normalised Normalised

Type Type

(m22K/W) K/W) (m

(MJ/m22) ) (MJ/m

(MJ/m22) ) (MJ/m

(MJ/m22) ) (MJ/m

to Ins. Ins. CCB B to

Ins-­‐CB Ins-­‐CB

1.48 1.48

28.3 28.3

0.3 0.3

28.6 28.6

1.0 1.0

CB

0.62

56.3 56.3

0.1 0.1

56.2 56.2

2.0 2.0

Ins-­‐BV

1.72

32.5 32.5

10.4 10.4

42.9 42.9

1.5 1.5

Ins-­‐LW

1.69

48.4 48.4

13.7 13.7

62.1 62.1

2.2 2.2

Table 1: Comparison of Energy Usage – Controlled Interior

R1.69) m module, odule, ddespite espite hhaving aving aan n RR-­‐value -­‐value 114% 4% hhigher igher tthan han tthe he Ins-­‐CB Ins-­‐CB The Ins-­‐LW module (R1.69) (R1.48), used 117% more eenergy. nergy. EEven ven tthe he IIns-­‐BV ns-­‐BV ((Insulated Insulated BBrick rick VVeneer) eneer) m module odule ((R1.72) R1.72)

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in zone the Sw outh frican context given that the research was in aC m oderate climatic ith tAemperature ranges comparable to those of uSndertaken outh Africa’s limatic Zone 4. zone with temperature ranges comparable to those of South Africa’s Climatic Zone 4. xx CLAY BRICK 87

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Total Energy (MJ/m2) Total Energy (MJ/m2)

60 50 40

70

Energy Use for Six Weeks Energy Use for10-07-2008 Six Weeksto 14-08-2008 From Week Ending From Week Ending 10-07-2008 to 14-08-2008

60

Total

Total

Cooling Cooling Heating Heating

50 40

30 30 20 20 10 10 0 0

(R0.62) CBCB (R0.62)

Ins.CB (R1.48) Ins.CB (R1.48)

Ins.BV (R1.72) Ins.BV (R1.72)

Module Module

InsLW (R1.69) InsLW (R1.69)

Figure 1: Energy Usage for 6 week period July-August, 2008 Figure 1: 1 E: nergy Usage for f6or w6eek period July-­‐August, 2008 Figure Energy Usage week period July-­‐August, 2008

efficiency, with internal brick veneer insulated lightweight in all situations – this As shown in 1: 1: being the more translating into 14% lower Greenhouse Gas (reverse brick veneer) As shown iFn igure Figure emissions. energy efficient of the two.

• The insulated lightweight (InsLW) walled building was wthe orst performer relative The insulated lightweight (InsLW) walled building as w the worst performer relative • Clay• to brick cavity walling was generally With the findings ofCB), both Australian all awll alling envelopes that contained thermal mass cavity brick and and to walling envelopes that contained thermal m–ass – cavity b(rick (CB), moreinsulated energy befficient than insulated andbthermal modelling research veneer (InsBV).

Adding a sempirical kin of eoxternal rick veneer and/or reverse insulated rick brick veneer (InsBV).

Adding a skin f external brick veneer and/or reverse lightweight. correlating with three South African brick v eneer t o l ightweight w alling e nvelopes i mproved e nergy e fficiency, w ith brick veneer to lightweight walling envelopes improved energy efficiency, with • Clay brick cavity walling insulation modelling studies, namely the internal brick veneer (with reverse brick veneer) being the tm ore nergy efficient of the internal brick veneer (reverse brick veneer) being he meore energy efficient o130m² f the two. applied in the cavity was the most energy Standard House Energy Modelling Project, two.

• • Clay brick cavity walling was enerally more energy efficient than insulated efficient.

(Braune, 2010) using DesignBuilder Clay brick cavity walling wgas generally more energy efficient than insulated lightweight.

EnergyPlus software (2), Thermal Modelling lightweight.

Looking at the Australian thermal modelling of a 132m² CSIR house (Harris 2009) using study, done as input to the LCA of Brick Visual DOE software (8) and a 40m² Low 3 Products by Energetics (Pty) Ltd, Australia Cost House Energy Modelling Project, 3

(2010) for Think Brick Australia - http// (Braune, Gray, Oxtoby,2009/2010) (3) using www.thinkbrick.com.au (13), the combined DesignBuilder EnergyPlus software, the average Greenhouse Gas emissions from Clay Brick Association (CBA) commissioned the modelling of Verdant and Sirocco house a Parametric study of the outputs of types (two different floor plans), placed in modelling software (ASHRAE Standard 140 three locations and four orientations, with and Agrément SA compliant software such only the wall construction types differing, as DesignBuilder EnergyPlus and BSIMAC, and non-compliant software such as yielded findings per Table 2 Uninsulated double brick (cavity Ecotect™ V5.6) to better understand in what brick) was found to be more thermally respect the findings of different modelling efficient than insulated lightweight in most software applied to studies in South Africa situations, this translating into 7% lower differed. total average Greenhouse Gas emissions A Parametric Study of the outputs of while insulated cavity brick outperformed modelling software

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the loor pplans), lans), pplaced laced iin n tthree hree the mmodelling odelling oof f VVerdant erdant aand nd SSirocco irocco hhouse ouse ttypes ypes ((two two ddifferent ifferent ffloor locations a nd f our o rientations, w ith o nly t he w all c onstruction t ypes d iffering, y ielded locations and four orientations, with only the 7wall construction types differing, yielded CLAY xx BRICK 8 findings findings pper er TTable able 22 b below. elow.

TABLE HOUSE OUSE PPLANS LANS TABLE 22: : TTHERMAL HERMAL M MODELLING ODELLING O OF F V VERDANT ERDANT A AND ND SSIROCCO IROCCO H COMBINED MISSIONS O OVER VER 550 0 YYEARS EARS COMBINED AAVERAGE VERAGE HHVAC VAC GGREEN REEN H HOUSE OUSE G GAS AS ((kg kg CCO₂-­‐e) O₂-­‐e) EEMISSIONS Extracted ssessment Extracted ffrom rom EEnergetics nergetics FFull ull LLife ife CCycle ycle A Assessment Insulated Insulated Location Location

Four Four

Uninsulated Uninsulated

Orientations Orientations

Double Double BBrick rick

Insulated Insulated

Insulated Insulated

Timber Timber

Double Double

Timber Timber

more/(less) more/(less)

Brick Brick ((R1.3) R1.3)

Frame Frame

GHG tthan han GHG rick Double BBrick

Newcastle Newcastle

N,S,E&W N,S,E&W

Insulated Insulated Timber Timber more/(less) more/(less) GHG tthan han GHG Double BBrick rick Double Insulated RR1.3 1.3 Insulated

108273 108273

102471 102471

120913

11.67% 11.67%

18.00% 18.00%

146100 146100

127281 127281

145139

-­‐0.66% -­‐0.66%

14.03% 14.03%

129847 129847

130020 130020

145108

11.75% 11.75%

11.60% 11.60%

128073 128073

119924 119924

137053

7.01% 7.01%

14.28% 14.28%

Climatic Climatic Zone Zone Melbourne Melbourne

N,S,E&W N,S,E&W

Climatic Climatic Zone Zone Brisbane Brisbane

N,S,E&W N,S,E&W

Climatic Climatic Zone Zone Average GGHG HG Average

N,S,E&W N,S,E&W

That study, “Addouble Parametric Energy Modelling comparable energytthan usage findings Uninsulated ouble rick ((cavity cavity rick) was as ffound ound taccurate Uninsulated bbrick bbrick) w o be more thermally efficient fficient han insulated lightweight n m most ost sResidences situations, ituations, tthis his ranslating nto 7 7% % wall llower ttotal ofinsulated Middlelightweight Income 130m² for for different construction iin ttranslating iinto ower otal aaverage verage types applied Greenhouse as missions w while hile nsulated avity bbto rick utperformed iinsulated llightweight Greenhouse GGas eemissions iinsulated ccavity rick ooutperformed nsulated ightweight South African Conditions in Six Climatic different building typologies subjected to in aall ll ssituations ituations his ranslating nto 11Walling 4% llower ower G Greenhouse reenhouse Gas in –– t this ttranslating iinto 4% G as eemissions. missions.

Regions in South Africa, with Four unsteady state external climatic conditions.

Systems”, 2012) (10), found: This study, “A Review of ComputerWith the the (Johannsen findings of of both both Australian empirical and and thermal thermal modelling research With findings Australian empirical modelling research correlating correlating • with Ecotect software produced basedthe Calculation Methods for Energy Simulating with three modelling South African African modelling studies, namely namely the 130m² Standard House three South modelling studies, 130m² Standard House Energy findings on average, 35% at variance with Unsteady-state Heat Transfer through modelling software that used ASHRAE Walling Systems”, (Johannsen, 26 February 4 4 2013) (11), considered the fundamental complaint formulas.

• Ecotect failed to respond adequately equations used in the different software to the addition of thermal capacity in governing heat conduction through multiwalling modelling. layer walling and the different methods of solving these equations.

The review (page 6) noted that: A review of algorithms for best simulating annual energy performance of buildings During an annual energy simulation, Using the above parametric study the outdoor thermal environment changes findings as a reference, a study was continuously on an hourly and daily basis commissioned by the CBA to identify which due to the following effects: modelling software had the capacity to give • Hourly changes of ambient temperature;

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•

Hourly, often irregular, changes of diffuse solar radiation due to variations in cloud cover; • Hourly, often irregular, changes of direct solar radiation reaching the wall due to changes in the sun’s position, variations in cloud cover and effects of external shading; • Hourly changes in wind speed; • Daily changes in all abovementioned parameters.

In addition, there may also be day-to-day variations in indoor environment due to variations in usage patterns or in internal heat gains.

The review of the fundamental equations and methods for solving them (2013:3-12) led to the conclusion: • The CTF (Conduction Transfer Coefficient) method as applied in ASHRAE compliant modelling software (Design Builder Version 3 and BISMAC Version 9) is suitable for calculating heat conduction through walls with any pattern, however irregular, of external and internal variations, including hourly and daily changes in weather parameters.

• The CTF method may be considered the most suitable method for computer based calculations of unsteady state conduction through multi-layer walling constructions and annual energy simulations of buildings.

• For calculating CTF coefficients the State Space method is preferred in lieu of its simplicity and computation advantages.

(This software package has been certified

by Agrément South Africa for use in terms of SANS 10 400 – XA Rational Designs and energy modelling).

• Design Builder Version 3.1 and BISMAC Version 9, both fully implement the CTF method and would be suitable for the University of Pretoria modelling study.

xx CLAY BRICK

With regard to Ecotect software, the review (1986:12-14) identified that the Admittance method, a frequency response method for calculating a cyclical response to a periodic pattern of external variations (CIBSE 1986; Rees, Davies, Spitler, Haves 2000), was used for calculating heat conduction.

A key assumption of the Admittance method, relating to heat conduction through walls, is that variances in the outdoor thermal environment or boundary conditions are assumed to fluctuate sinusoidally in a 24 hour cyclic pattern.

The review however noted that: • During an annual energy simulation, the outdoor thermal environment changes continuously on an hourly and daily basis.

These variations can be highly irregular, far removed from the sinusoidal pattern assumed in the Admittance method.

• Based on this general principle, the key assumptions of the Admittance method related to heat conduction through walls are generally not valid during an annual energy simulation.

While Johannsen could not obtain information on the internal working of Ecotect software to interrogate the equations applied in Ecotect, he could not, by virtue of the evidence from the parametric study and Ecotect’s application of the Admittance method, endorse the use of Ecotect as suitable for the University of Pretoria thermal modelling study.

Other information that bears consideration on the merits of Ecotect in providing accurate comparative energy usage for different wall construction types includes: In the tutorial “Introduction to Ecotect™ V5.6 modelling software”, (Lin J., 2007 pp 1) (14), Assistant Professor Juintow Lin makes the following points:

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CLAY xx BRICK

87

Table 3 -­‐ Gross annual heating and cooling energy for 2000 m² office in each climate zone expressed in kWh Table 3 -­‐ Gross annual heating and cooling energy for 2000 m² office in each climate zone expressed in kWh Climatic Zone

Climatic Zone

Wall Types 1

1 2

2 3

3

Wall Types 220mm Solid Clay Brick 220mm Solid Clay

Brick 270mm Cavity (50mm) Clay Brick 270mm Cavity with NO insulation (50mm) Clay Brick 280mm Cavity with NO insulation (50mm) Clay Brick 280mm Cavity with insulation (50mm) Clay Brick

with insulation Light Steel Frame to SABS 517 Light Steel Frame to

SABS 517

01

02

Bloemfontein 01

Pretoria 02

Bloemfontein 51088

51088 52630

52630 56178

56178 68921

68921

Pretoria 82892

82892 87268

87268 93772

93772 117083

117083

03 Musina 03

Musina 222937

04

Cape Town 67032

222937 228858

67032 71218

228858 236063

71218 78817

236063 250258

05

Cape Town04

78817 105389

250258

105389

06

Durban

05

Upington

Durban 140756

190548

140756 148191

190548 192934

148191 158572

192934 197806

158572 180980

180980

06

Upington

197806 209769

209769

Table Gross annual and w cooling energy forXA 2000 moffice in each climate zone Clay brick 3c-onstruction in in heating compliance ith SANS 10400 Building Regulations and SANS expressed in kWh 204 E nergy E fficiency S tandards p erformed b etter t han L SF s pecified S ANS 5 17 w ith 2 20mm Clay brick construction in in compliance with SANS 10400 XA Building Regulations and SANS solid double Ebfficiency rick being the best pperformer for day-­‐time occupancy.

204 Energy Standards erformed better than LSF specified SANS 517 with 220mm

V5.6 is a ttool modelling software with that solid ouble brick being he bfor est architects performer tofor dcompliant ay-­‐time occupancy.

• dEcotect™ of empirical research at the University of test their designs.

• It isTable annual heating and cooling energy for 40 mNewcastle, ² house in each Australia, climate zone ePriority xpressed in kWh not 4 a-­‐ Gross validation tool to extract Research Centre absolute values. for Energy, would indicate that the of Table 4 -­‐ Gross annual heating and cooling energy for 40 m² house in each climate zone expressed in koutputs Wh • It should not be used to determine the South African thermal modelling studies using Climatic Zone amount of energy used i.e. watts per day etc. ASHRAE compliant modelling software (2, 3, Climatic Zone04 01 are DOE 02 05 06 • More accurate programs – 2 and 8),03 provide a more accurate account of the Bloemfontein Pretoria Musina Cape Town Durban Upington Wall Types Energy Plus. real thermal performance and energy usage 01 02 03 04 05 06 220mm Solid Clay 1464 1055 1282 734 590 Durban 2428 • 1Ecotect™ a simpler algorithm of different wall construction types modelled Pretoria Musina Cape Town Upington Wall TypesV5.6 uses Bloemfontein Brick Admittance for thermal under South African climatic conditions.

220mm Clay method 270mmSolid Cavity 1 1464 1055 1282 734 590 2428 (50mm)Brick Clay Brick while 1009 2calculations 725 887 The recent 479 thermal454 1904research other programs modelling with NO insulation 270mm Cavity namely DOE – 2 and Energy Plus use undertaken by the University of Pretoria 280mm Cavity 2 1009 725 887 479 454 1904 (50mm) Clay Brick (50mm)formulas.

Clay Brick 3ASHRAE 496 379 2 218 to a full 296 1244 below, as input Lifecycle Assessment with NO insulation with insulation 280mm Cavity of the brick industry in South Africa, adds to (50mm) Brick 3 496 379 2 218 296 1244 SteelClay Frame to In 4the Light Paper “Qualitative of the pointing 945 Comparison 1082 1135 credence 868of the above, 827 2054 the way with insulation SABS 517 North American and U.K Cooling Load forward for specifying and applying walling Light Steel Frame to 4 1082 1135 868 827 2054 Calculation Methods”, 945(Rees, Davies, envelopes for greatest heating and cooling SABS 517 Spitler, Haves, 2000), (2000:93 paragraph energy efficiency in South Africa.

In the case of a 40m² house 220mm solid double brick is more energy efficient than LSF ‘Conclusions and Future Developments’), The University of Pretoria Thermal specified 517 in that three in of trespect he six climatic while cavity brick is generally more (18), itSANS is noted of thezones Modelling Study: In tapplication he case of aof 4than 0m² hSF ouse 220mm solid ouble brick m ore energy than LSF “A energy efficient specified Smethod: ANS 517 dw ith LSF only is m arginally better than cavity the LAdmittance The University of efficient Pretoria study specified S ANS 5 17 i n t hree o f t he s ix c limatic z ones w hile c avity b rick i s g enerally m ore brick i n C limatic Z one 1 .

T he f indings h ighlight t he c ontribution i nsulation R 1.0 ( 30mm • “the methods used to treat solar heat Thermal Performance Comparison Between extruded polystyrene) rovides to the thermal f high thermal m ass clay brick wall energy efficient than LpSF specified Sstandards ANS 517 ewfficiency ith oonly marginally bMethods etter than cavity gains are simplified by current SixLSF Wall Construction Frequently construction in CZlimatic , the insulated brick wcalls affording 4insulation 7.5% lower heating and brick in Climatic one 1. ZTone he 1findings highlight the ontribution R1.0 (30mm and cannot be expected to give accurate Used in South Africa”(Vosloo, Harris, Holm, extruded polystyrene) provides to the thermal efficiency of high thermal mass clay brick wall results except in a limited range of van Rooyen, Rice 2015) (19) that used construction in Climatic Zone 1, the insulated brick walls affording 47.5% lower heating and Design Builder Energy Plus software and circumstances”.

The sum total of the above, and particularly that has passed critical review (Dr. Rainer 8 the correlation in the outputs of ASHRAE Zah of Quantis International (2015: 81-82) 8

116 110

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Table 4 -­‐ Gross annual heating and cooling energy for 40 m² house in each climate zone expressed in kWh Table 4 -­‐ Gross annual heating and cooling energy for 40 m² house in each climate zone expressed in kWh

xx CLAY BRICK

Climatic Zone

Climatic Zone 01 Wall Types 1

1 2

2

Wall Types 220mm Solid Clay 220mmBrick Solid Clay Brick 270mm Cavity (50mm) Brick 270mmClay Cavity with NOClay insulation (50mm) Brick

02

Bloemfontein 01

Bloemfontein 1464

1464 1009

1009

Pretoria 02

Pretoria 1055

1055 725

725

03

04

05

06

Musina 03

Cape 04Town

Durban 05

Upington 06

Musina

Cape Town

Durban

Upington

1282

734

590

2428

1282

734

590

2428

887

479

454

1904

887

479

454

1904

280mm Cavity with NO insulation 3

3 4

4

(50mm) Brick 280mmClay Cavity with insulation (50mm) Clay Brick

with insulation Light Steel Frame to SABSFrame 517 to Light Steel

SABS 517

496

496 945

945

379

379 1082

1082

2

218

296

1244

2

218

296

1244

1135

868

827

2054

1135

868

827

2054

- Gross and cooling 40 mhouse each climate zone expressed In Table the c4ase of aannual 40m² hheating ouse 220mm solid energy double for brick is more inenergy efficient than LSF in kWh In t he c ase o f a

4 0m² h ouse 2 20mm s olid d ouble b rick i s m ore e nergy e fficient t han SF specified SANS 517 in three of the six climatic zones while cavity brick is generally mLore specified SANS 517 in Lthree of the sSix climatic while avity brick bis etter generally ore energy efficient than SF specified ANS 517 wzones ith LSF only cm arginally than cmavity energy pecified SANS 517 with oinsulated nly marginally better than cavity of the University ofL1SF Pretoria study 1, Lthe walls 47.5% brick in eCfficient limatic tZhan one . Tshe findings hreport ighlight the cSF ontribution ibrick nsulation Raffording 1.0 (30mm brick i n C limatic Z one 1 .

T he f indings h ighlight t he c ontribution i nsulation R 1.0 ( 30mm (19), modelled the energy usage of three lower heating and cooling energy than the extruded polystyrene) provides to the thermal efficiency of high thermal mass clay brick wall extruded p olystyrene) p rovides t o t he t hermal e fficiency o f h igh t hermal m ass c lay b rick all building typologies, namely a 2000m² insulated lightweight walls R2.2 (100mm construction in Climatic Zone 1, the insulated brick walls affording 47.5% lower heating aw nd construction in Climatic Zone 1, t(Table he insulated walls affording 47.5% ower heating and office/institutional building 2), a brick glass wool insulation) in lcompliance with 40m² subsidy house (Table 3) and a 130 m² SANS 204 Energy Standards for non-masonry standard house (Table 4) in the six major buildings for Climatic Zone 1. climatic zones of South Africa.

In the case of the 130m² house, cavity 8

Tables 3, 4 and 5 below represent the brick presents as generally more energy 8 comparative gross heating and cooling efficient than LSF specified SANS 517, with energy of four of the different wall insulation applied in the cavity of the brick construction types modelled. walls optimising the efficiencies in all six Clay brick construction in in compliance climatic zones. Given that the insulation with SANS 10400 XA Building Regulations applied to the brick construction has an and SANS 204 Energy Efficiency Standards R-value some 50% less than for LSF specified performed better than LSF specified SANS SANS 517, and that energy usage of 517 with 220mm solid double brick being insulated brick is between 30 and 96% lower the best performer for day-time occupancy. than LSF specified SANS 517 depending on In the case of a 40m² house 220mm solid the climatic zone, it is understandable that double brick is more energy efficient than LSF best pay back for insulation applied is the specified SANS 517 in three of the six climatic preserve of clay brick construction. zones while cavity brick is generally more energy efficient than LSF specified SANS Summary of University 517 with LSF only marginally better than of Pretoria findings: cavity brick in Climatic Zone 1. The findings Tables 3, 4 & 5 show that for the 4 wall highlight the contribution insulation R1.0 construction types depicted: (30mm extruded polystyrene) provides to • Solid 220mm double brick masonry the thermal efficiency of high thermal mass walling (or for Climatic Zone 4: a 270mm clay brick wall construction in Climatic Zone clay brick cavity wall, as is the norm

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87

xx BRICK CLAY

Table 5 -­‐ Gross annual heating and cooling energy for 130 m² house in each climate zone expressed in kWh Table 5 -­‐ Gross annual heating and cooling energy for 130 m² house in each climate zone expressed in kWh Climatic Zone Climatic Zone

Wall Types Wall Types 1

2

01 01 Bloemfontein Bloemfontein

02 02 Pretoria Pretoria

03 03 Musina Musina

04 04 Cape Town Cape Town

05 05 Durban Durban

06 06 Upington Upington

1

220mm Solid Clay 220mm Solid Clay Brick Brick

4405 4405

2797 2797

787 787

2242 2242

909 909

4762 4762

2

270mm Cavity 270mm Cavity (50mm) Clay Brick (50mm) Clay Brick with NO insulation with NO insulation

3251 3251

2023 2023

78 78

1618 1618

619 619

3682 3682

33

280mm 280mmCavity Cavity (50mm) (50mm)Clay ClayBrick Brick with withinsulation insulation

1855 1855

1164 1164

45 45

872 872

322 322

2228 2228

44

Light LightSteel SteelFrame Frameto to SABS SABS517 517

2650 2650

2492 2492

1199 1199

2104 2104

1358 1358

3908 3908

Table 5 - Gross annual heating and cooling energy for 130 mhouse in each climate zone expressed In tin the ase oof f tthe he 1130m² 30m² hhouse, cavity brick efficient than kWh In he ccase rick ppresents resents aas s ggenerally enerally mmore ore eenergy nergy efficient than LSF sspecified pecified SSANS ANS 5517, 17, w with insulation applied optimising the LSF pplied iin n tthe he ccavity avity oof f the the bbrick rick wwalls alls optimising the non-masonry for the Capezones. condensation efficiencies in Southern ix cclimatic limatic Given nsulation pplied bb rick efficiencies in aall ll ssix iven tthat hat tthe he iiEfficiency nsulation aaStandards pplied to to the tfor he rick problem areas) is the smost buildings). construction as n RR-­‐value -­‐value 0% less LLSF and that energy construction hhas aan ome 5thermally ess tthan han ffor or SF sspecified pecified SSANS ANS 5517, 17, and that energy and energy befficient walling30 system usage o f i nsulated rick i s b etween a nd 9 6% l ower 517 usage of insulated brick is nd 96% lower tthan han LLSF SF sspecified pecified SANS SANS 517 considered for day-time or non- Thermal masspay internal walling versus depending he cclimatic limatic one, iit t iis insulation depending oon n tthe zzone, s uunderstandable nderstandable tthat hat bbest est pay bback ack for for insulation residential occupancy commercial/ lightweight: applied is is tthe he ppreserve reserve oof f cclay lay bbrick rick cconstruction. applied onstruction. institutional type buildings.

In the development of the SANS 204:2010 • Clay brick masonry cavity walling is, in standard for Energy Efficient Buildings most situations, the more thermally and in South Africa ‘A Novel Algorithm for Summary niversity of f P Pretoria retoria energyoowalling system o considered forffindings: all Determining the Active Thermal Capacity Summary f f UUniversity indings: day or residential occupancy buildings. of Masonry Walling’ (Holm, Harris, Burton, Tables 33, , 44 & & 5 s show how tthat hat ffor or tthe he 4 4 w types ddepicted: Tables wall all cconstruction onstruction 2010),types (9) it epicted: was recorded that the CR 270mm 5clay brick masonry cavity wall Method (Holm et al 2010) demonstrates construction increases performance as • Solid 220mm double brick masonry walling (or for Climatic clay • Solid 220mm double brick masonry walling (or for Climatic ZZone one 44: a: a2 70mm 270mm clay thebrick thermal resistance increases with that small amplitude ratios require highaCact cavity wall, as is the norm for the Southern Cape condensation problem reas) brick c avity w all, a s i s t he n orm f or t he S outhern C ape c ondensation p roblem areas) insulation in the cavity. values (active thermal capacity), temper is the madded ost thermally and energy efficient walling system considered for to day-­‐time or is t he m ost t hermally a nd e nergy e fficient w alling s ystem c onsidered f or d ay-­‐time • Thenon-­‐residential most energy efficient South African the indoor climate to within the required or occupancy commercial/institutional type buildings. non-­‐residential commercial/institutional type buildings. comfort range reducing artificial heating walling system foroccupancy the two residential

and cooling energy.

When insulation buildings is the 280mm insulated cavity • Clay brick masonry cavity walling is, in most situations, the more thermally and is • brick Clay masonry brick masonry cavity winsulation alling is, in most situations, the m and wall.

Notably the middle ofore twothermally homogeneous energy walling system considered for all placed day or in residential occupancy buildings. energy w alling s ystem c onsidered f or a ll d ay o r r esidential o ccupancy b uildings. in 270mm the masonry cavity (R1.0),cavity this wtoall construction masonry layers, thenperformance the active thermal clay brick masonry increases as the 270mm lay bproducts rick mincreases asonry cavity all ccapacity onstruction increases performance as the provide a crCR (combination of the interior leaf is seven times as thermal esistance with w insulation added in the cavity. r esistance i ncreases w ith i nsulation a dded i n t he c avity. ofthermal thermal capacity “C” and resistance effective as that of the outside leaf.

The inmcompliance with SANS This correlation active thermal •“R”) ost energy efficient South A204 frican walling system for between the two residential • Energy The mstandards ost eis nergy emasonry fficient South Acfrican alling sand ystem for N the two irnsulation esidential buildings greater energy efficiency buildings the for 280mm insulated avity capacity bw rick masonry wall. otably in is the buildings i s t he 2 80mm i nsulated c avity b rick m asonry w all.

N otably ithe nsulation in the (voluntary standard), delivers significantly demonstrated in the findings of empirical masonry cavity (R1.0), this to provide a CR products (combination of thermal masonry c“avity (R1.0), this tand provide a research CR products (combination of sttandards hermal superior thermal lower the University of Newcastle where capacity C” aperformance nd resistance “o R”) in compliance wat ith SANS 204 Energy for capacity “bC” and resistance “R”) in compliance wsith SANS partition 204 Energy tandards energy usage to that of LSF specified clay brick internal walls improvedfor masonry uildings (voluntary standard), delivers ignificantly superior tshermal masonry buildings (voluntary standard), delivers significantly superior thermal SANS 517 (R2.2 for Climatic Zones 2, 3, energy efficiency no matter the external wall 4 & 5 and R1.9 for Climatic Zones 1 & 6 construction type. In the case of the insulated 9 in compliance with SANS 204 Energy lightweight external walled timber frame 9

112 118

THEGREEN GREENBUILDING BUILDINGMATERIALS MATERIALSAND ANDTECHNOLOGIES TECHNOLOGIESHANDBOOK HANDBOOK THE

The chouses omparative of tbhermal mLass is evidenced the energy ratings of 1S0 how Show (Table v6alue below) uilt at the andcorp Western iAn ustralia ‘Revolution Road’ houses (Table 6 b, elow) Landcorp Western Australia ‘tRevolution Road’ Show project Seville bGuilt rove ait n tPhe erth, for suppliers to demonstrate he environmental house xx 8 to demonstrate the environmental CLAY BRICK 7 house project, Seville Ghrove in Perth, for suppliers compliance of their ouses. compliance of their houses.

Table 6 Table 6

LANDCORP WESTERN AUSTRALIA WESTERN AUSTRALIA 10 SHOW HOUSE LANDCORP ENVIRONMENTAL COMPLIANCE ASSESSMENT -­‐ PERTH 10 SHOW HOUSE ENVIRONMENTAL COMPLIANCE ASSESSMENT -­‐ PERTH

HOUSE TYPE HOUSE TYPE ECO FAB 1 ECO FAB 1 FABABODE : ABODE FABABODE : ABODE THE BENCHMARK THE BENCHMARK THE PINNACLE THE PINNACLE THE SOLACE THE SOLACE

CONSTRUCTION METHOD CONSTRUCTION METHOD

WALLING MATERIAL WALLING MATERIAL

ENERGY RATING ENERGY RATING

Lightweight Steel Studwork Lightweight Steel Studwork

Lightweight Steel Lightweight Steel

5 Stars 5 Stars

Prefabricated Lightweight Prefabricated Lightweight Construction with a Pre-­‐ Construction with a SPlab re-­‐ stressed Concrete stressed Concrete Slab

Ecoply Cladding Ecoply Cladding

5 Stars 5 Stars

2020 Easy Build System 2020 Easy Build System

Steel Fabrication Steel Fabrication

6 Stars 6 Stars

Steel framed – Fridge Panel Steel framed – Fridge Panel System Insulated System Insulated Concrete Slab and Timber Concrete Slab and Timber Frame Frame

Clad with custom ORB -­‐ Clad with custom ORB -­‐ Colour Bond Colour Bond

5 Stars 5 Stars

Blueboard and Gyprock Blueboard and Gyprock

6 Stars 6 Stars

THE SUNHOUSE THE SUNHOUSE

2020 Easy Build SSystem ystem 2020 Easy Build

Steel Fabrication Steel Fabrication

6 Stars 6 Stars

THE YRENT THE YRENT

2020 Easy Build SSystem ystem 2020 Easy Build

Steel Fabrication Steel Fabrication

6 Stars 6 Stars

Aerostone Twin PPanel anel Aerostone Twin System System

Hebel Panel Hebel Panel

6 Stars 6 Stars

Slab on ground DDouble ouble Slab on ground Brick and TTile ile Brick and

Double Brick Double Brick

8 Stars 8 Stars

PANEL DISPLAY TWIN TWIN PANEL DISPLAY JADE 8JADE 08 808

building, applying clay brick internal partition

walls improved thermal efficiency by 20% (Energy Efficiency and the Environment, The case for Clay Brick, Edition 4), (5).

In the University of Pretoria study (19), a sensitivity study found that the premium on energy usage as a consequence of using lightweight wall partitioning systems to be between 20 and 30% over that of the three clay brick masonry wall types studied (2015-11).

Summation of findings: • On the evidence provided above Light Steel Frame wall construction as presently specified in SANS 517 is not as thermally efficient and uses more heating and cooling energy compared to clay brick masonry cavity walls in all climatic regions.

• Clay brick walling envelopes in compliance with SANS 10400-XA provides options for achieving superior thermal performance to that of LSF as presently specified SANS 517.

• For daytime occupancy buildings, 11 solid 11 220mm double clay brick (R-value = 0.45) in compliance with SANS 10 400 Part XA (R-value = 0.35) is the most thermally efficient for all six climatic zones (Table 3).

• For all day occupancy and residential buildings studied, 270mm cavity brick (R-value =0.65) in compliance with SANS 10400 Part XA (R-value =0.35) is generally more thermally efficient than LSF specified SANS 517 (Tables 4 &5).

• For all day occupancy and residential buildings, 280mm cavity brick with insulation (R-value =0.5) applied in cavity (Climatic zone 3 & 5) & R-value = 1.0 (Climatic zones 1, 2, 4 & 6), will facilitate optimal energy efficiency with lowest heating and cooling energy usage.

The modelling studies (2 & 8) found energy usage to be 24% plus lower on average for the six climatic zones than LSF specified SANS 517 while the study “Thermal Modelling of a 132m² CSIR house by Structatherm Projects (Harris H 2009) using Visual DOE software”

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(8) found that insulated cavity brick provided best energy savings for the cost for insulation applied.

Thermal Mass and Passive Solar Design for Optimising Energy Efficiencies: To achieve the most cost effective energy efficiencies for buildings the principles of passive solar design have an important contribution to make. By applying the basics of correct orientation, by shading significant windows, by installing high levels of roof insulation, and with the placement of thermal mass in strategic positions such as the walls and floor slabs, low cost energy efficiency can be achieved.

The employment of thermal mass in the external walls ensures a thermal lag in the heat transfer to the interior of a building, and in combination with internal brick walls contribute to absorb, store and release heat energy when it is needed. This goes to help moderate indoor temperatures ensuring that they are within the thermal comfort zone for longer periods before heating or cooling is invoked.

The comparative value of thermal mass is evidenced in the energy ratings of 10 Show houses (Table 6) built at the Landcorp Western Australia ‘Revolution Road’ Show house project, Seville Grove in Perth, for suppliers to demonstrate the environmental compliance of their houses.

Only the clay brick house (Righthomes. com.au/sustainable/Jade 808 Sustainable Home (17)) achieved an 8 Star Energy Rating per Australia’s Building Energy Rating System (BERS). The brick house was designed along Passive Solar Design principles but then so were some of the seven steel framed lightweight walled houses that received only 5 and 6 Star Energy Ratings. Thermal mass was the differentiating factor in their thermal performance.

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The value of thermal mass was conclusively shown in the thermal performance study, “A Thermal Performance Study of Common Australian Residential Construction Systems in Hypothetical Modules”, (Gregory, Moghtaderi, Sugo, Page, 2010) (7). The study found thermal mass to significantly reduce the energy usage in residential buildings through its propensity to maintain a comfortable internal temperature with little heating or cooling.

It was a conclusion of that study that: “to create a sustainable future thermal mass in buildings needs to be utilised” (2010:9-10).

Conclusion: The University of Newcastle empirical testing of the walling systems of four housing modules and the Pretoria University energy modelling of the three building types conclusively prove that the application of thermal mass is the prerequisite for achieving energy efficient buildings rather than thermal resistance alone.

Double brick walls provide superior levels of day-time thermal comfort and lowest energy usage in day-time occupancy buildings, while double brick cavity walls afford generally superior day-night thermal efficiencies in South Africa’s six major climatic zones.

The specification of thermal insulation in the cavity of clay brick walls is to achieve optimal thermal performance and energy efficiency. SANS 204 Energy Efficiency standard Tables 3 and 4 provide the CR Product tool for designers to put together the appropriate combinations of thermal mass and thermal resistance to achieve energy efficient walling. The LSF walling propositions as presently specified in SANS 517 are comparatively less thermally efficient and present an energy efficiency compromise.

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References •

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Alterman A., Page A.W., Moffiet T., Moghtaderi B., (2015)), A Measure for the Dynamic Thermal Performance of Walling Systems Incorporating the Combined Effect of Thermal Mass and Thermal Resistance, Priority Research Centre for Energy, University of Newcastle, Journal of the International Masonry Society, Masonry International, Vol 28. No1. 2015 Braune M., (2010), External Wall Types Assessment for 130m² Residence, WSP Green by Design Braune M., Gray W., Oxtoby S., (2009/2010), 40m² Low Cost Housing Energy Modelling Project, WSP Green by Design Conradie D., (2014), The Performance of Innovative Building Technologies in South African Climatic Zones, The Green Building Handbook South Africa The Essential Guide, Volume 6, pp165-187 Energy Efficiency and the Environment - The case for Clay Brick – Edition 4, www.thinkbrick.com.au Kumarai T., and Conradie D., (2012), Thermal Mass vs. Insulation Building Envelope Design in Six Climatic Regions of South Africa, The Green Building Handbook South Africa, The Essential Guide, Volume 4, pp 201-215 Gregory K.E., Moghtaderi B., Sugo H., Page A.,(2010), A Thermal Performance Study of Common Australian Residential Construction Systems in Hypothetical Modules, School of Engineering, The University of Newcastle pp 9-10 Harris H., (2009), Thermal Modelling of a 132m² CSIR house using Visual DOE software, Structatherm Projects Holm D., Harris H., Burton A.W., (February 2011), A Novel Algorithm for Determining Active Thermal Capacity of Masonry Walling in the Setting of Energy Efficient Building Standards for South Africa, 9th Australian Masonry Conference, Queenstown New Zealand, 15-18 February 2011, pp 8-9 Johannsen A., (2012), A Parametric Energy Modelling of Middle Income 130m² Residences for South African Conditions in Six Climatic Regions in South Africa, with Four Walling Systems Johannsen A., (26 February 2013), A Review of Computer-based Calculation Methods for Simulating Unsteady-state Heat Transfer through Walling Systems Landcorp Review, (April 2010), ‘Revolution Road’ Project, Seville Grove, Perth, Landcorp Western Australia LCA of Brick Products, Life Cycle Assessment Report, (February 2010), Energetics (Pty) Ltd, for Think Brick Australia - http//www.thinkbrick.com.au Lin J., (October 29, 2007) Tutorial - Introduction to Ecotect™ V5.6 modelling software, Cal Poly Panoma Department of Architecture (www.toolsforsustainability.com) Page A.W., Moghtaderi B; Sugo H. O; Hands S; (2009), A Study of the Influence of the Wall R-value on the Thermal Characteristics of Australian Housing, University of Newcastle, Australia Page A.W; Moghtaderi B., Alterman D., Hands S., (2012), A Study of the Thermal Performance of Australian Housing, Priority Research Centre for Energy, Priority Research Centre for Energy, The University of Newcastle, Australia, www.thinkbrick.com.au Righthomes.com.au/sustainable/Jade 808 Sustainable Home Rees S.J., Davies M.G., Spitler J.D., Haves P., (January 2000), Qualitative Comparison of North American and U.K Cooling Load Calculation Methods published in HVAC & R Research Volume 6, No 1, January 2000 Vosloo P., Harris H., Holm D., van Rooyen N., Rice G., (April 2015), A Thermal Performance Comparison Between Six Wall Construction Methods Frequently Used in South Africa, Department of Architecture, University of Pretoria

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THE USE OF RAMMED EARTH FOR HOUSE CONSTRUCTION IN SOUTH AFRICA Paul Marais

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his paper presents a case study as part of a Professional Doctorate research project discussing an ecological approach to housing in South Africa, where lime stabilised rammed earth walls with polymer stabilised earth foundations have been used to construct a house in South Africa. Rammed earth was chosen as a construction method for its low embodied energy and thermal mass characteristics.

The subsurface strata upon which the house was built comprised of clayey, gravely, sandy soils that have resulted as a result of decomposition of granitic rocks. In order to ensure solid founding conditions the foundations were excavated to a depth of one and a half metres before the excavated material was stabilised and backfilled. The material was stabilised to 600mm below top of floor level with 2% Portland cement and above that with a 5% polymer bitumen mixture reinforced with horizontal steel reinforcing rods. This foundation avoids the use of reinforced concrete and as a result a significantly smaller carbon footprint, while fulfilling the functional requirements of supporting the building and preventing rising damp. The polymer has, as it major component is bitumen emulsion, provided a waterproof layer. Sabilised rammed earth walls of 500mm thickness were constructed on the foundation up to 4.2 meters in height and initial observations suggest that the walling and foundations are satisfactory with no settlement or cracking detected.

This paper discusses a case study of a house, north of Johannesburg, South Africa, which was designed and built in 2014 following an ecological approach, by constructing all the walls with rammed earth. The rammed earth walls have a low embodied energy and were sourced entirely from the site upon which the house was built and stabilised with 4% lime by mass. Additional to this small quantities

of natural oxides were used to colour the walls, and coupled with horizontal steel reinforcement were the only imported materials used in the walling for the house The paper also discusses a solution to one of the disadvantages of rammed earth walls, which is that due to their width (500 mm for the case study presented) these often require large reinforced concrete footings; which reduces their ecological benefits substantially. Thus, the paper discusses the foundation design and construction and reviews other alternatives considered for rammed earth foundations and describes the salient features of the design and construction for the polymer that was used. A good review of rammed earth construction is provided by Maniatidis and Walker [1] where they emphasize the need for the foundation to be water resistant and sufficiently deep.

Rammed Earth Housing Context Earth building offers a sustainable solution to housing in South Africa but has poor acceptability in the region [2]. Prior research that examined acceptability of earth building looked at adobe houses with respondents having the perception that earth buildings are subject to collapse as they are both affected by rain and are not as strong as a clay brick and cement mortar house [2]. Current research by the authors on perceptions shows promise that rammed earth has greater acceptability than other earth construction methods in southern Africa. Most housing in South Africa is built using bricks and mortar with clay fired bricks being the most common type [3]. Rammed earth construction cost has been found to compare favourably with brick and mortar construction, with formwork and labour costs the biggest component. This research is investigating both the acceptability of rammed earth as an earth construction

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method for affordable housing, with early positive results, as well as exploring cost efficient and suitable construction practices for the southern African region.

Case Study South African House A rammed earth house was constructed in the north of Johannesburg (Fig. 1) 25o 54’ S/ 27o 56’ E designed with both a low embodied energy as well as an energy efficient design.

The national standards of South Africa require masonry walls to have a R value of 0,35m2K/W and as rammed earth has a value of 0,35 to 0,7m2K/W for a 300mm thick wall [1] it was deemed prudent to exceed this to achieve more than the minimum thermal performance. Walls were to reach a maximum height of 4,2 meters and at a slenderness ratio of 10 [1] would result in a wall of 420mm thickness minimum. Thus, a wall width of 500mm was chosen that exceeded both these specifications. The walls were rammed from soil from the site coloured with natural oxides and stabilised with 4% hydrated lime. The house was roofed with corrugated iron, insulated with 70mm rigid insulation below, with 800mm roof overhangs to provide both summer shading and protect the rammed earth walls.

Figure 1 North View of rammed earth house Rammed earth foundations The exterior walls of the project were 500mm thick and as such would require foundation walls of the same width or more as described by the rammed earth standard [4]. The options for the footings that were considered included standard

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concrete strip footings, cement stabilized earth footings and polymer stabilized earth footings. The carbon footprint of each system was roughly determined to derive a comparison between the systems. The concrete strip footings were deemed to have a carbon footprint with a cube of concrete having between 100 to 300 kg of CO2 [5]. The 2% cement stabilised earth would have a carbon footprint of 40 to 80kg/ m3 with cement having a carbon footprint of 250 kg/m3 [5]. The 5% polymer stabilised earth had an estimated carbon footprint of 20 to 40kg/m3 with the main components being bitumen SS60 and urea with a carbon footprint for bitumen being 102kg per tonne [6].

In comparing the different foundation options the volume of the foundations was also taken into consideration with the polymer stabilised earth being the largest, as it required deeper foundations than the reinforced concrete. The reinforcing steel content of each foundation system was deemed to be the same, so is not included in the comparison, in practice however, only horizontal reinforcing bars were used in the polymer stabilised earth foundation compared to a cage construction, that uses both horizontal and vertical steel reinforcement in reinforced concrete. It was estimated by the engineer, Hans Brink, that the polymer reinforced earth foundation required half of the steel of a reinforced concrete foundation. The results of this comparison is summarised in the following table (Table 1).

In the final foundation design chosen a combination of 2% Cement stabilised earth with 5%Polymer Stabilised earth was used, so the final saving of CO2 emissions was 46% over a concrete strip foundation. Bitumen production is inefficient in South Africa with a CO2 emission of 102kg per tonne as a result of low energy costs in the past [7] compared

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concrete. It was estimated by the engineer, Hans Brink, that the polymer reinforced earth foundation required half of the steel of a reinforced concrete foundation. The results of this comparison is summarised in the following table

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RAMMED EARTH xx (Table 1).

Table 1 Comparison of foundation types carbon dioxide emisionsFoundation type Concrete Strip 2% Cement stabilised 5% Polymer 2% Cement with 5% polymer above

Kg CO2 per m3 of material 150 40 30 70

Foundation width (mm) 800 700 700 700

Foundation depth (mm) 600 1050 450 1500

Foundation area (m2) 0,48 0,735 0,315 1,05

Kg CO2 per linear m of foundation =72 =29,4 =9,45 =38,85

% CO2 used 100% 41% 13% 54%

% CO2 saved 0% 59% 87% 46%

final foundation chosen atypes combination of 2% Cement stabilised earth with 5%Polymer Stabilised TableIn1theComparison ofdesign foundation carbon dioxide emisions-

earth was used, so the final saving of CO2 emissions was 46% over a concrete strip foundation. Bitumen production is inefficient in South Africa with a CO2 emission of 102kg per tonne as a result of low energy costs in the past [7] compared withof figures of 26-35kg tonnethe the norm in Europe [6] so future work on optimising its CO compressive strength (UCS) as2 emission well as with figures 26-35kg per per tonne norm would improve the carbon footprint of this material significantly.

their water resistance. After placing and compacting the foundation material DCP tests were taken at regular intervals to ensure The Walls of the rammed earth house have a maximum height of 4, 2 metres and a width of 500mm and a the offoundations reached strength. maximum dry density of 2027kg/m3 [8] resulting in a static load 8513kg/m2 from the walls.sufficient The roof was a lightweight steelDesign structure at a ten-degree slope, with timber beams and waterproofness purlins. The foundationsofused (figure2) were Foundation The the Polymer a combination of cement-stabilised earth with a polymer-stabilised layer above. The foundation width was 700mm The Walls of the rammed earth house stabilised earth was also a desirable quality wide, the width of the Tractor-Loader-Backhoe (TLB) bucket, so very easy to excavate and wider than the rammed earth wall so providing aheight stable footing. excavatedfor to athe depthfloor of 1500mm dynamic cone have a maximum of 4,The2 TLB metres slab, before and would also result in penetrometer (DCP) tests were taken along the entire foundation bed to ensure that this bed was stable and no and a width of 500mm and a maximum a far lower carbon footprint and therefore undermining was present. The material excavated was mixed with 2% cement, backfilled and compacted back in 3 dry density 2027kg/m [8] done resulting the floor slab waswas made of two 150mm layers. of DCP testing was again to ensurein that sufficient compaction achieved.

The 150mm top 450mmthick 2 mixed with of the 8513kg/m polymer and backfilled and compacted.

The polymer used trades under the name ofearth.

Ecobond, a was static load from the walls. layers of 5% polymer stabilised This and comprises a plasticiser, urea, and SS60 bitumen emulsion. The percentages of stabilisation required were The roof was a lightweight structure wasofdone concurrently the foundations determined by testing samples made steel up of different percentages Ecobond in a laboratorywith and testing their compressive strength (UCS) as wellbeams as their water resistance. an Afterimpermeable placing and compacting the atunconfined a ten-degree slope, with timber creating 200mm layer foundation material DCP tests were taken at regular intervals to ensure the foundations reached sufficient strength. and The purlins.

The foundations used (figure2) below the floor of the house.

Compaction waterproofness of the Polymer stabilised earth was also a desirable quality for the floor slab, and would also result in far lower carbon footprint and therefore the floor slab madeon of two thick layers of 5% were a acombination of cement-stabilised waswas done the150mm material below the floor polymer stabilised earth. This was done concurrently with the foundations creating an impermeable 200mm layer earth with a polymer-stabilised layer above. to ensure that it had a good bearing surface The foundation width was 700mm wide, the before the stabilised earth was spread out width of the Tractor-Loader-Backhoe (TLB) and compacted to the design requirement. bucket, so very easy to excavate and wider Two subsurface drains were installed at than the rammed earth wall so providing right angles to the slope, and function by a stable footing. The TLB excavated to a diverting any subsurface water past the sides depth of 1500mm before dynamic cone of the house thereby leading subsurface water penetrometer (DCP) tests were taken along away from the footings. One drain was installed the entire foundation bed to ensure that this at 300mm below the top of foundation height bed was stable and no undermining was and a second drain was installed at 1500mm present. The material excavated was mixed below top of foundation height. These would with 2% cement, backfilled and compacted ensure that no water would build up against back in 150mm layers. DCP testing was again the stabilised earth foundations, and were done to ensure that sufficient compaction done as a precaution to protect the earth was achieved. The top 450mm was mixed building. A further precaution was a swale at with the polymer and backfilled and the highest point of the property that diverted compacted. The polymer used trades under surface water around the buildings the name of Ecobond, and comprises a plasticiser, urea, and SS60 bitumen emulsion. Foundation construction method The percentages of stabilisation required Polymer stabilised earth is a technology that were determined by testing samples made was developed for road building and as such up of different percentages of Ecobond in was designed to be applied at scale with a laboratory and testing their unconfined the use of extensive plant [9]. In this case in Europe [6] so future work on optimising its3.4COFoundation emissionDesign would improve the carbon 2 footprint of this material significantly.

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Figure 2 Foundation and wall design by Hans Brink

Figure 2 Foundation and wall design by Hans Brink study we were using the product in a house where different methods were required, to road building with far higher number and variety of under floor services, see Figure 2.

This section discusses what we did and why and the difficulties we encountered.

The building practise in South Africa is to install the services in the floor slab where possible. Usually the foundations, and foundation walls are built, and the subfloor compacted before the electrical and plumbing services are completed.

Thereafter the floor slab is cast with the services being cast into its thickness. As we were compacting the floor simultaneously as the foundation walls, as well as the concern that the compaction would damage the services, or possibly disturb their location, it was deemed necessary to lay these underneath the stabilised floor slab before it was compacted. As the site was sloping down from south to north, an earth platform built up in 150mm compacted layers was constructed to within 200mm of the underside of the floor slab. Usual practise is to measure the location of the services off the foundation walls, to overcome this pegs were placed by an engineering surveyor at

each point and a colour combination of tags used to differentiate between gas, electrical and plumbing services. A rotating laser level was used to determine floor heights on all these pegs so that the services could be set to the correct levels, critical to the drainage.

These services were set 200mm below the bottom of the foundation and conduits were all equipped with draw wires so that any slight compaction at bends would not be problematic. Thereafter the earth was compacted above the services creating a hard subsurface for the polymer earth floor, (see Fig. 3 and 4). Then the trenches were excavated to 1,5 metre depth by the TLB, with some difficulty found in avoiding the services, those that crossed trenches required temporary removal. The cementstabilised earth was mixed by hand and the polymer stabilised earth with a rotary mixer before being placed and compacted by a rammer.

Gauging of the cement stabilisation mixture was by standard 65 litre builders’ wheelbarrows, as per standard construction practise in the region. The mixing of the polymers was more difficult as they required greater precision and being

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cut into the floor to create a key for the rammed earth walls (figure2). Formwork was erected directly on the floor slab (figure 6), and where necessary it was chopped down to level (figure 5) and the walls were rammed directly

xx onto this with a damp proof course deemed unnecessary.

RAMMED EARTH 9 8 The rammed earth was reinforced with two rows of

bitumen covered 12mm steel reinforcing rods with 90 degree bends below all openings as well as two rows of bitumen covered 12mm steel reinforcing rods at the top of the wall.

Table 2: Quantities of mix for 4 wheelbarrow gauge (260l) as well as water required for mix to be at Optimum Moisture Content (OMC) Part 1 1,2 l

Part 2 3,2 l

Part 3 153ml

Part 4 5,9l

1% OMC 4,9l

2%OMC 9,9l

3%OMC 14,8l

4%OMC 19,7l

TableFigure 2: Quantities of mix for 4 wheelbarrow gaugeFigure (260l) as well as water required for mix to be 3 Completed Cement Stabilisation 4 Compacting a polymer stabilised layer at Optimum Moisture Content (OMC) designed for road stabilisation they were delivered in quantities designed for mass preparation in large vehicles. A method of using plastic containers cut to size, as per table 2, was devised to suit the four barrow rotary mixer, both improving efficiency and avoiding problems of incorrectly reading a measurement. Optimum moisture content (OMC) was measured before each mix to determine the required water to be added.

The OMC was determined by adding a chemist’s teaspoon of water (5ml) to a can of loose soil (340ml by volume and 500g by weight) until the soil holds a ball that breaks when tapped. Each spoon of water is a per cent of the OMC. The stabilised polymer was far more difficult to compact to level, it has the workability of sticky toffee and the presence

of the services, sticking up vertically through the floor, prevented us using a large roller as recommended by the Ecobond supplier (figure 4) so a plate compactor was used.

The floor was laid in 3m wide strips with gauge boards set up on both sides and a long straight edge used to level the material between them. The boards were levelled using 16mm diameter steel pegs, which provided a quick and easy method to set up a level to work from. Initial compaction was done with a rammer with the final compaction done with a plate compactor.

A roller compactor had been recommended but as the distances between services were too small for it to pass, a plate compactor was used instead.

The positions of the walls were then marked out on this floor surface and a

Figure 3 Completed Cement Stabilisation

Figure 4 Compacting a polymer stabilised layer

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Figure 5 Polymer stabilised layer chopped down to level

Figure 6 Erecting rammed earth formwork onto stabilised base

100mm wide by 30mm deep groove cut into the floor to create a key for the rammed earth walls (figure2). Formwork was erected directly on the floor slab (figure 6), and where necessary it was chopped down to level (figure 5) and the walls were rammed directly onto this with a damp proof course deemed unnecessary. The rammed earth was reinforced with two rows of bitumen covered 12mm steel reinforcing rods with 90 degree bends below all openings as well as two rows of bitumen covered 12mm steel reinforcing rods at the top of the wall.

is derived that gives an indication of in-situ strength. The CBR is an indirect measure of the soil strength based on its resistance to penetration. By comparing a large number of laboratory tests with field CBR values models have been developed to derive the unconfined compressive strength (UCS).

A conversion that UCS = 15 x CBR0.88 has been derived [10] From the data collected graphs were plotted together with the CBR values (figure 8,9). Minimum CBR values had been determined by the engineer from the laboratory analysis and the loads the building was to withstand and DCP testing allowed immediate identification of any areas that were below the design specification Heavy rains during the process of stabilisation hampered progress with a storm of 40 minutes resulting in 60mm of rain, the subsurface drains installed worked as designed removing most of the water.

The polymer hardens and forms long chains through a dehydration process and this was significantly hampered by the surrounding wet ground (see position 7, (Figure 8)).

Site Testing and findings Testing of the ground beneath the foundations, the cement stabilised earth and the PSE as well as the rammed earth was done with a dynamic cone penetrometer (DCP) at the positions numbered 1 to 16 (figure 7). A DCP consists of a 8kg mass dropping 575mm and knocking a 20mm diameter cone with a 60o point into the material being tested. The DCP measures the penetration rate per blow and from these results a California Bearing Ratio (CBR)

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Ecobond, the polymer used, gains strength when the polymer chains cross link and this occurs as it dries. The foundations were covered with plastic sheeting to prevent direct rain ingress, but the saturated surrounding soil had an impact on the rate the material gained strength. The ramming programme had to be adjusted to commence at the southeast corner as the northwest corner remained waterlogged for considerable time, but on drying the design strength was obtained.

These unsatisfactory results, caused by the excessively moist surrounding soil, can be seen at position 6, which is well under design strength of a CBR of 50(figure 9).

Fortunately design strength was gained over the next 60 days, so that by the time construction of the rammed earth walls commenced the CBR value had exceeded 50. If this hardening had not occurred through the slow dehydration process, removing and replacing the PSE would have been required..

The advantage of the PSE floor was a lower carbon footprint, a waterproof layer underneath the building, and the cost saving of using material from site. A further advantage was found where services needed relocation, when it was found that it

was easier to chop the PSE, as it was softer than concrete, and relocate the services with the new PSE material bonding very well with the existing material. A disadvantage of the process is that it requires compaction by layers, whereas reinforced concrete is faster and easier to place. The mixing of the PSE was complicated involving precise measurements of four different components on site, and difficulty was experienced in getting small quantities. Obtaining a flat and level surface of the PSE also proved difficult with variations in level of about 30mm throughout as a result of its sticky consistency. A cement based screed was required for the final floor finish, and this was used to achieve a satisfactory level finish. Concrete, which is the usual choice, has the advantage that it can be floated to a very smooth level finish Discussion Initial findings have shown that the foundation methodology is satisfactory with the rammed earth walls showing no signs of differential settlement. Ramming of the walls was done with pneumatic rammers in layers no more than 75mm thick and the DCP results were well above the design, as a result of prior layers receiving additional

Figure 7 DCP test positions

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Figure 8: DCP plot of level below foundations 1500mm deep compaction from above, except at the very top of the wall (figure 10) where less compaction occurs. The only cracks found in the rammed earth are those below the window openings as a result of shrinkage (figure 10). These cracks were identified early in the construction process, and were eliminated by the placement of four 12mm diameter reinforcing rods, bent 90o at the ends, below each window.

Conclusions This paper was a case study of a rammed earth house that used PSE foundations for their lower CO2 emissions, and initial investigation show that this construction method was satisfactory, cost effective and that a 46% of CO2 emissions saving was achieved. The polymer earth foundations performed as designed with no settlement or movement shown in preliminary investigations, within the first year. The method of DCP testing adopted from road construction was an effective test method that allowed strength of the material to be

easily, quickly and inexpensively tested on site.

Further investigation is necessary to optimise the construction practises, and determine the best way to accommodate services. A more suitable polymer that has higher strength, easier workability and lower cost may also be found, and alternate low CO2 materials for foundations should be explored. The polymer requires specific soil conditions and a chart that specifies its suitability for particular earth type needs to be developed. Bitumen emulsions are also used with the addition of small quantities of cement, and their suitability should be investigated as they have lower cost. The range of earth types suitable for stabilisation needs further investigation, as well as guidelines that allow designers to choose the most appropriate solution without the need for extensive prior testing.

Acknowledgements Hans Brink PrEng determined the structural requirements of the rammed earth, as

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Figure 9: DCP plot of level below rammed earth, from top of PSE of 450mm thickness

Figure 10: DCP results or rammed earth wall

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well as the foundations, and was responsible for determining the testing required and the method for doing it. He offered valuable advice on the construction methodology particularly with the mixing, and levelling of the polymer earth mix. Denis Loffell PrEng for sharing freely his experience his advice on construction methodology as well as sharing freely his experience and calculations with bitumen based stabilisers.

Figure 11 Shrinkage cracks References • •

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[1] Vasilios Maniatidis & Peter Walker, A Review of Rammed Earth Construction, Natural Building Technology Group, Department of Architecture & Civil Engineering, University of Bath, May 2003 [2] Bosman, G. & Steÿn, J.J. The story of the great plans of mice and men: selling sustainable earth construction. Edition:1st, Human Settlements Review, South Africa, Pretoria: Bothabela Printers. (pp.

196-216), 2010 [3] G. A. Rice and P. T. Vosloo, A life cycle assessment of the cradle-to-gate phases of clay brick production in South Africa, Eco-Architecture V: Harmonisation between Architecture and Nature. Edited A. Brebbia, R. Pulselli, WIT press, (p 471), 2014 [4] SADCSTAN/TC 1/SC 5/001/FDHS SAZS 724, Rammed Earth Code of Practice, January 2012 [5] Natural Ready Mixed Concrete Association, Concrete CO2 Fact Sheet, Silver Spring Maryland, June 2008 [6] Neville, B, Carbon footprint calculators for Asphalt, Murray & Roberts, Road Pavement Forum, 2010 [7] C Bergh Energy Efficiency in the South African Crude Oil Refining Industry: Drivers, Barriers and Opportunities, University of Cape Town, May 2012 [8] GeoCivilLab civil and geotechnical engineering laboratory services, Report AD130722, August 2013.

[9] Construction Industries development board, Labour based methods and technologies for employment intensive works, A CIBD guide to best practice – Part 4-6 Emulsion treated gravel, March 2005.

[10] P Paige-Green and L Du Plessis, The use and interpretation of the dynamic cone penetrometer (dcp) test, Version 2, CSIR Built Environment, Pretoria, September 2009

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127 133

INDEX OF ADVERTISERS COMPANY

PAGE

ArcelorMittal 2-3 Argitek 80 BASF Holdings IBC Berlux 62 Builders OBC Cape Contours

87 Claybrick 110 Corobrik 106-107 Evapco 16 Geberit Southern Africa 76 Green Code Designs & Property 75 Hansgrohe 23 Hydraform 8 Institute for Timber Construction 67 Lilliput 78 Mapei 55 The National Home Builders Registration Council (NHBRC) 18-19 Nordic Paper & Packaging (NPP) 6 Mercedes-Benz 4 Prodigious 24 SIG Energy 60 Shaluza Projects 30 Sika South Africa 10 South African Wood Preservers Association (SAWPA) 37 University of Johannesburg

46 Utility Management for Africa (UMFA) 58 Van Dyck 14 Viega 66-67 134

THE GREEN BUILDING MATERIALS AND TECHNOLOGIES HANDBOOK

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