The comfort–carbon paradox: post-occupancy evaluation of thermal mass, comfort, and carbon resilience in four contemporary UK homes

Achieving net-zero housing requires balancing embodied carbon reduction with thermal comfort and climate resilience. This challenge, referred to as the comfort–carbon paradox, remains poorly understood in private residential sector. This study addresses this gap through a novel integration of a mixed-method approach to examine how thermal mass, building services, and occupant behaviour influence both comfort and carbon performance. Four privately developed UK dwellings (EPC A/B), representing masonry, insulated concrete formwork (ICF), and timber-frame construction, were investigated using environmental monitoring, energy-use data, occupant surveys, interviews, and LCA modelling. Results show that high-thermal-mass masonry dwellings achieved greater temperature stability and lower overheating risk during the 2022 heatwave, while whole-life carbon differences between heavyweight and lightweight constructions were smaller than expected. Service replacement cycles and occupancy patterns significantly influenced long-term emissions. The findings demonstrate that net-zero housing requires an integrated approach combining thermal resilience, whole-life carbon thinking, durable services, and occupant engagement.