Energy Efficiency Applications in Buildings presents an investigation into the energy use and measures to improve the energy efficiency of existing building stock in the UK. The aim of this research is to assess the domestic energy use of statistically representative residential buildings and their occupants’ thermal comfort by considering the significant impact of overheating risks on energy consumption and occupants’ well-being. Divided into two volumes, the books present energy consumption and thermal comfort in the construction sector as a complex socio-technical problem that involves the analysis of an intrinsic interrelationship amongst dwellings, occupants, and the environment. Using case studies, the authors demonstrate the significance of improving energy efficiency on the impact on occupants of long-term heatwaves in the summer. Additionally, the volumes demonstrate how dynamic thermal energy simulation can be used as a learning laboratory for future trends in housing energy consumption reduction. Volume 1: Theories, Methods, and Tools presents the background to the research and the assessment methods and tools adopted by the research team. Volume 2: Performance Evaluation and Retrofitting Strategies describes the case studies and building performance and post occupancy evaluations, before making strategic policy and retrofitting recommendations. The research and roadmap presented in these volumes can be used as a guidance tool for building energy modelling and performance simulation, enabling architects, building engineers, and other practitioners to close the gap between the current understanding and the actual performance of existing building stocks.