How do energy efficiency measures affect the risk of summertime overheating and cold discomfort? Evidence from English homes

Governments’ policies worldwide seek to improve the energy efficiency of housing stocks. In temperate climates, there are concerns that energy efficiency measures increase the risk of summertime overheating. A systematic evidence review screened 311 documents reporting the effect of energy efficiency measures on overheating. The temperatures in 750 English living rooms and bedrooms measured as part of the Energy Follow-up Survey during the hot summer of 2018 were re-analysed. The frequency and intensity with which temperatures exceeded thresholds associated with overheating and cold discomfort were calculated. The re-analysis revealed that energy efficiency measures had the desired effect: they kept rooms significantly warmer, reducing the occurrence of cold discomfort. However, none of the energy efficiency measures examined, nor the overall efficiency of the dwelling, significantly affected the frequency of overheating. In fact, loft and wall insulation may reduce overheating risk in houses. Built form, whether a house or flat, had a significant impact on the frequency of overheating. More work is needed on the risk of overheating in very highly insulated dwellings. It is concluded that policies aimed at improving the energy efficiency of dwellings complement those concerned with climate adaptation.