Low Impact Building

This guide to the designs, technologies and materials that really make green buildings work will help architects, specifiers and clients make informed choices, based on reliable technical information. Low Impact Building: Housing using Renewable Materials is about changing the way we build houses to reduce their 'carbon' footprint and to minimise environmental damage. One of the ways this can be done is by reducing the energy and environmental impact of the materials and resources used to construct buildings by choosing alternative products and systems. In particular, we need to recognise the potential for using natural and renewable construction materials as a way to reduce both carbon emissions but also build in a more benign and healthy way. This book is an account of some attempts to introduce this into mainstream house construction and the problems and obstacles that need to be overcome to gain wider acceptance of genuinely environmental construction methods. The book explores the nature of renewable materials in depth: where do they come from, what are they made of and how do they get into the construction supply chain? The difference between artisan and self-build materials like earth and straw, and more highly processed and manufactured products such as wood fibre insulation boards is explored. The author then gives an account of the Renewable House Programme in the UK explaining how it came about and how it was funded and managed by Government agencies. He analyses 12 case studies of projects from the Programme, setting out the design and methods of construction, buildability, environmental assessment tools used in the design, performance in terms of energy, air tightness, carbon footprint and post-occupancy issues. The policy context of energy and sustainability in the UK, Europe and the rest of the world is subjected to a critical examination to show how this affects the use of natural and renewable materials in the market for insulation and other construction materials. The debate over energy usage and embodied energy is discussed, as this is central to the reason why even many environmentally progressive people ignore the case for natural and renewable materials. The book offers a discussion of building physics and science, considering energy performance, moisture, durability, health and similar issues. A critical evaluation of assessment, accreditation and labelling of materials and green buildings is central to this as well as a review of some of the key research in the field.

Tom Woolley is an architect and educator and self-builder. He has taught at the Architectural Association, Strathclyde University, Hull School of Architecture, Queens University Belfast, University of Central Lancashire, UiTM in Malaysia, University of Umea, the Centre for Alternative Technology in Wales, University of Bath and University of Gloucestershire. His research work and writing has covered housing policy, sustainable materials and design theory. He is active in the Co-operative party, ARC-PEACE and Scientists for Global Responsibility. He has helped to establish the Alliance for Sustainable Building Products in the UK. Working with Rachel Bevan Architects in County Down in Northern Ireland, he is also involved in organic gardening and sustainable woodland management.

Acknowledgements x Figure credits xi Introduction xii The Renewable House Programme xiv The expansion of natural building xiv The wider environmental agenda xv Chapter overview xvii References xviii 1 Renewable and non-renewable materials 1 Synthetic, manmade materials 2 Limitations of synthetic materials 3 Questioning claims about recycling 4 Resource consumption problem with synthetic materials 7 Renewable materials - insulation 9 Carbon sequestration and embodied energy 10 Performance and Durability of natural materials 11 Natural renewable materials commercially available 11 Low impact materials 22 References 23 2 Case Studies: twelve projects in the Renewable House Programme 26 Abertridwr Y Llaethdy South Wales 29 Drumalla House, Carnlough, County Antrim 35 Blackditch, Stanton Harcourt, Oxfordshire 40 Callowlands, Watford 44 Domary Court, York 49 Inverness 55 Long Meadow, Denmark Lane, Diss 59 LILAC, Leeds 64 Tomorrow's Garden City, Letchworth 68 Reed Street, South Shields 76 The Triangle, Swindon 80 Pittenweem 88 References 92 3 The Renewable House Programme: a strange procurement! 94 Monitoring and evaluation 103 References 106 4 Analysis of issues arising from the case studies 107 Success in using natural renewable materials 107 Adapting conventional timber frame construction for using natural materials 109 The importance of getting details right and using details appropriate for eco materials 110 Problems with designs and the need to get warranty approvals for changes of details 111 Weather issues and hempcrete 112 Decision of Lime Technology to go for prefabrication in future and whether this is the best option 114 Using wood fibre products and issues related to construction and components 115 References 116 5 Attitudes to renewable materials, energy issues and the policy context 118 Why attitudes and policies affect the use of renewable materials 118 Climate change and energy efficiency targets 118 What is carbon? 119 Sustainable construction and energy policies 120 UK Code for Sustainable Homes 121 New planning policy framework 123 The zero carbon myth 123 The carbon spike concept 125 Energy in use or 'operational energy' is all that matters to many 126 How embodied energy was discounted 128 Carbon footprinting 132 Passive design approaches 133 Do natural and renewable materials have lower embodied energy? 133 Carbon sequestration in timber 136 Wood transport issues 137 Carbon sequestration in hemp and hempcrete 138 The Green Deal 139 Official promotion of synthetic insulations 140 Other attitudes hostile to natural materials - the food crops argument 142 Transport and localism 143 Cost 144 References 145 6 Building physics, natural materials and policy issues 148 Holistic design 149 European standards, trade and professional organisations 151 Building physics - lack of good research and education 154 Lack of data and good research on sustainable buildings 155 Energy simulation and calculation tools 157 Assessment of material's environmental impact and performance 160 Moisture and breathability and thermal mass 164 Breathability 168 Thermal mass and energy performance in buildings 170 Building physics research into hempcrete 174 Indoor air quality 178 References 183 7 Other solutions for low energy housing 187 Hemp lime houses 187 Hemp houses in Ireland 189 Local sheep's wool in Scotland 192 Strawbale houses in West Grove, Martin, North Kesteven, Lincolnshire 192 Timber experiments 194 Scottish Housing Expo 197 Using local materials? 197 Greenwash projects? 199 So-called 'carbon neutral' developments 202 Earth sheltered building 203 BRE Innovation Park 204 Masonry construction for low energy houses 205 Blaming the occupants 209 Back to the 60s and 70s - déjà vu 210 References 211 8 A future for renewable materials? 214 Middlemen 216 Postscript 217 References 219 Glossary/Abbreviations 220 Index 227