Design Intent compared with Performance in Practice: Residential Heat Networks with Combined Heat and Power Christopher Nicholas Marien Darwin College Department of Engineering University of Cambridge This dissertation is submitted for Doctor of Philosophy September 2019 Declaration This dissertation is the result of my own work and includes nothing which is the outcome of work done in collaboration except as declared in the Preface and specified in the text. It is not substantially the same as any that I have submitted, or, is being concurrently submitted for a degree or diploma or other qualification at the University of Cambridge or any other University or similar institution except as declared in the Preface and specified in the text. I further state that no substantial part of my dissertation has already been submitted, or, is being concurrently submitted for any such degree, diploma or other qualification at the University of Cambridge or any other University or similar institution except as declared in the Preface and specified in the text. It does not exceed the prescribed word limit for the relevant Degree Committee. Christopher Nicholas Marien cnm29 Acknowledgements This research would not have been possible without the support of my industry sponsor and employer calfordseaden LLP. I would like to express my gratitude to my supervisor Dr Sebastian Macmillan. Our discussions and his guidance have been invaluable to this research and my progression as a researcher. A further special thanks to my external industry advisor Dr Terry Keech for his continued professional and academic support. Page 2 of 335 Christopher Nicholas Marien Design Intent compared with Performance in Practice: Residential Heat Networks with Combined Heat and Power Abstract The GLA’s London Plan includes planning policies that require developers to adopt a range of energy efficient measures and low/zero carbon technologies to reduce CO2 emissions below the Building Regulations baseline. Such polices have consequently formed a new aspect of the planning appraisal process, where the assessment of energy, CO2 and technology is now a material consideration of planning approval. Developers must submit an energy strategy to demonstrate how their design proposals achieve the policy targets. The GLA uses these documents as evidence to evaluate the outcomes of the existing policy and direct future policy decisions. The GLA’s findings suggest that their policies have been successful in reducing CO2 emissions. The vast majority of reductions are attributed to heat networks with CHP. However, there is little evidence of the actual performance of these technologies in practice, including the scale of CO2 emissions reductions delivered. This research adopted a mixed method approach to evaluate if the local energy policies which promote the adoption and implementation of heat networks and CHP are leading to the anticipated reductions in CO2 emissions. This research found that the prescriptive approach to the London Plan policy discourages context specific assessment and can lead to a practice of compliance-over-performance when deciding on the most appropriate technology to adopt. The prescribed assessment methodology was also found to be inadequate to appropriately assess the deliverable performance and would therefore, result in an energy performance gap. The research also found that design assessment measures are available to provide a more reasonable assessment of deliverable performance reducing the gap, but are not used in practice. Furthermore, those responsible for implementing the policy do not expect that the assessed performance of heat networks and CHP or the scale of CO2 emissions saved will be achieved in practice, contrary to the GLA findings. Page 3 of 335 Contents Declaration ................................................................................................................................ 2 Acknowledgements ................................................................................................................... 2 Abstract ..................................................................................................................................... 3 Contents .................................................................................................................................... 4 List of Tables .............................................................................................................................. 7 List of Figures ............................................................................................................................. 9 List of Abbreviations ................................................................................................................ 12 CHAPTER 1: RESEARCH INTRODUCTION.................................................................................. 14 1.1 Motivation ..................................................................................................................... 14 1.2 Context and Focus ......................................................................................................... 15 1.3 Aims and Objectives ...................................................................................................... 17 1.4 Thesis Structure ............................................................................................................. 19 1.5 Chapter Reflectance ...................................................................................................... 20 CHAPTER 2: LONDON’S CLIMATE CHANGE STRATEGY ............................................................ 21 2.1 The UK’s Climate Change Strategy for New Building Developments ............................ 21 2.2 The London Plan – Response to Climate Change .......................................................... 24 2.3 Preparing an Energy Strategy ........................................................................................ 28 2.4 Analysis of the London Plan Energy Policies ................................................................. 38 2.5 Informing Local Energy Policy ........................................................................................ 50 2.6 Chapter Reflectance ...................................................................................................... 57 CHAPTER 3: THE APPLICATION OF HEAT NETWORKS AND CHP IN RESIDENTIAL BUILDINGS 58 3.1 Heat Networks ............................................................................................................... 58 3.2 A Brief History of Heat Networks in the UK .................................................................. 60 3.3 Combined Heat and Power............................................................................................ 61 3.4 A Brief History of CHP in the UK .................................................................................... 61 Page 4 of 335 3.5 Reducing CO2 Emissions from Buildings ........................................................................ 63 3.6 Feasibility Assessment of Heat Networks and CHP ....................................................... 64 3.7 Chapter Reflectance ...................................................................................................... 81 CHAPTER 4: THE ENERGY PERFORMANCE GAP ....................................................................... 83 4.1 Definition of the Energy Performance Gap ................................................................... 83 4.2 The Energy Performance Gap Research ........................................................................ 85 4.3 Chapter Reflectance .................................................................................................... 103 CHAPTER 5: RESEARCH QUESTIONS AND RESEARCH DESIGN ............................................... 104 5.1 Research Justification and Intended Contribution to Knowledge............................... 104 5.2 Research Questions ..................................................................................................... 105 5.3 Research Design ........................................................................................................... 106 5.4 Chapter Reflectance .................................................................................................... 114 CHAPTER 6: EXAMINATION AND ANALYSIS OF ENERGY STRTAGEY DOCUMENTS ............... 115 6.1 Document Analysis Method ........................................................................................ 115 6.2 Findings and Key Themes ............................................................................................ 122 6.3 Reflection on Document Analysis Findings ................................................................. 148 6.4 Chapter Reflectance .................................................................................................... 152 CHAPTER 7: POST-OCCUPANCY ENERGY ANALYSIS OF A HN-CHP SYSTEM .......................... 153 7.1 The Case Study Method ............................................................................................... 153 7.2 Identification of the Case Study .................................................................................. 156 7.3 Evaluation Method ...................................................................................................... 161 7.4 The Case Study ............................................................................................................. 174