Empirical assessment of summertime overheating risk in new, retrofitted and existing UK dwellings

This paper statistically assesses the hourly internal summertime temperature datasets gathered during the summer of 2013 (May to September), from 63 dwellings across the UK. The sample consisted of unmodified dwellings (existing); dwellings with varying levels of fabric improvements (retrofitted) and dwellings constructed to higher levels of the Code for Sustainable Homes (new). Indoor and outdoor temperature data from bedrooms and living rooms from these homes were collected at five-minute intervals using temperature sensors. These data were processed and analysed for summertime overheating, using both static criteria (CIBSE Guide A) and the criteria associated with the EN15251 adaptive thermal comfort model (CIBSE TM52). The results show that despite a relatively cool summer, sufficiently high temperatures were found in a high proportion of dwellings, which were found to be overheated according to the CIBSE static temperature criteria, although the prevalence of overheating was found to be much lower when assessed by the adaptive method. Considerably higher temperatures were found in bedrooms, much higher than living rooms. Interestingly, dwellings with higher levels of insulation experienced overheating twice as frequently as uninsulated dwellings. Given the prevalence of overheating found across the sample, it is necessary to carefully consider this risk during the design and retrofit of homes, to avoid the growth of domestic air-conditioning in future