Elm Tree Mews Field Trial – Evaluation and Monitoring of Dwellings Performance Final Technical Report Dr. Jez Wingfield, Centre for the Built Environment, Leeds Metropolitan University Prof. Malcolm Bell, Centre for the Built Environment, Leeds Metropolitan University Dominic Miles-Shenton, Centre for the Built Environment, Leeds Metropolitan University Dr. Jenny Seavers, Centre for Urban Development and Environmental Management, Leeds Metropolitan University January 2011 © Centre for the Built Environment, Leeds Metropolitan University, The Northern Terrace, Queen Square Court, Leeds, LS2 8AG Elm Tree Mews Field Trial Final Technical Report January 2011 Executive Summary 1 This report summarises the technical results and monitoring data from the Elm Tree Mews field trial carried out by the Centre for the Built Environment at Leeds Metropolitan University on behalf of the Joseph Rowntree Foundation (JRF) and Joseph Rowntree Housing Trust (JRHT). The Elm Tree Mews Field Trial research programme was funded under JRF project No. 805319. This report details the technical data from fabric performance tests carried out on the completed dwellings, site observations and photographic records of the construction process and an analysis of available site documentation and drawings. Performance testing included pressure tests, a coheating test, thermal imaging, temperature and air flow measurements and heat flux measurements. A design retrospective of those aspects of the design and construction process related to energy performance was undertaken by an assessment of available documentation and through a series of semi-structured interviews with key individuals involved with the development. The report also contains the results of 12 months in-use monitoring of the occupied dwellings and data on the performance of the communal heat pump system. 2 This report should be read in conjunction with the main final policy report for the Elm Tree Mews project which is published by the Joseph Rowntree Foundation (Bell, Wingfield, Miles-Shenton & Seavers, 2010). The final policy report contains all the discussions, conclusions, recommendations and policy implications arising from the project. Acknowledgements 3 The Elm Tree Mews project was supported by the Joseph Rowntree Foundation and the Joseph Rowntree Housing Trust, who were the scheme developers. The research was undertaken by the Centre for the Built Environment at Leeds Metropolitan University. The project was carried out over four years, and in that time we have been fortunate to have had the support of a large number of organisations and committed individuals who deserve our special thanks. The staff of the Housing Trust provided considerable support. In particular, we are grateful for the help and support given by Brian Jardine, Peter Giles and Nigel Ingram. From start to finish they have worked very hard to ensure that the project went as smoothly as possible. The design and construction team, subcontractors and others involved in the scheme deserve special thanks. In keeping with a general concern to maintain, as far as we can, the anonymity of the team, we are able to thank by name a few who have expressed a willingness to be identified. We would acknowledge the support and enthusiasm of Andy Watson, Andy Coates and Jason Kirby of the Strategic Team Group (main contractor) and Matthew Hill of Leeds Environmental Design Associates Ltd (services engineering). However, the contribution of all individuals and organisations involved in providing a pioneering scheme from which to learn was considerable and is gratefully acknowledged. This research project had the benefit of advice and support from an advisory group, the members of which we would also like to thank for their support. The range and depth of expertise available from the advisory group were considerable and their contribution invaluable. The advisory group consisted of Brain Jardine (JRHT), Dave Mitchell (HBF), Jayne Lomas (HCA), Prof. Bob Lowe (UCL), Prof. Kevin Lomas (Loughborough University), Richard Partington (Richards Partington Architects), Simon Corbey, (Good Homes Alliance) and Tanya Christensen (Consulting with Purpose). 4 No monitoring project can be undertaken without the cooperation and enthusiasm of the residents. They invite researchers into their homes, tolerate monitoring equipment in their daily lives and, in the process, facilitate the research. We are very grateful for their support and although anonymity prevents us from naming them, we acknowledge their considerable contribution. The staff at the Joseph Rowntree Foundation provided considerable support and advice to the research team and we would like to thank in particular the project officers Alison Jarvis and Katherine Knox for their help and unstinting enthusiasm throughout the project. In a project of the scale and complexity of Elm Tree Mews it is almost inevitable that we will have omitted to mention by name a number of people who have contributed. We can only apologise in advance to these individuals and express our general gratitude to all who have supported the project. Page 2 of 132 Elm Tree Mews Field Trial Final Technical Report January 2011 Table of Contents Executive Summary ...................................................................................................................................... 2 Acknowledgements ...................................................................................................................................... 2 Table of Contents ......................................................................................................................................... 3 Introduction ................................................................................................................................................... 5 Background .................................................................................................................................................. 5 The 21st Century Suburban Homes Competition ...................................................................................... 5 The Elm Tree Mews Field Trial ................................................................................................................. 5 Competition Design Submission ............................................................................................................... 6 Other Initial Contract Issues ..................................................................................................................... 7 Design & Construction Timeline ............................................................................................................... 9 Design and Construction Retrospective ..................................................................................................... 12 Interviews with Key Members of Design and Construction Team .......................................................... 12 Design Specification ............................................................................................................................... 13 Heating System Design, Installation and Commissioning ...................................................................... 14 Initial Performance of Heating System ................................................................................................... 18 Initial Performance of Solar Hot Water System ...................................................................................... 21 Control of Legionella Bacteria ................................................................................................................. 24 Ventilation System .................................................................................................................................. 24 Predicted Energy Performance ............................................................................................................... 24 Fabric Performance Tests .......................................................................................................................... 27 Airtightness ............................................................................................................................................. 27 Coheating Test ........................................................................................................................................ 32 Heat Flux Measurements ........................................................................................................................ 34 Party Wall Cavity Temperature Measurements ...................................................................................... 36 Thermal Imaging ..................................................................................................................................... 37 Party Wall Air Flow Measurements ......................................................................................................... 41 Background Ventilation Measurements .................................................................................................. 41 Construction & Design Observations ......................................................................................................... 42 Nominal Panel U-value versus Actual Panel U-value ................................................................................ 47 Thermal Bridging .......................................................................................................................................