Summer thermal comfort and overheating in the elderly

Abstract

Atypically warm summers such as 2003 and 2018 are predicted to become normal by 2050. If current climate projections are accurate, this could cause heat-related mortality to rise by 257% by 2050, the majority of which will be in vulnerable groups such as the elderly. However, little is known about the temperatures achieved in the homes of the elderly even in typical summers, and even less on whether these are comfortable. This study examines, for the first time, the validity of current thermal comfort models in predicting summer comfort levels in the 65+ demographic over a typical and an atypically warm summer. This was achieved through the first longitudinal study of thermal conditions in homes of the elderly in the South West UK, utilising repeated standardised monthly thermal comfort and health surveys with continuous temperature monitoring in both living and bed rooms. Results show that neither the PMV/PPD model (ISO 7730) nor the adaptive model (ISO 15251) accurately predict true thermal comfort in our sample. Overheating analysis using CIBSE TM59 (based on ISO 15251) suggests significantly more homes (50% living room, 94% bed room = 94% overall) overheated during the atypically warm summer, compared to the typical summer (3% living room, 57% bed room = 57% overall). These are worrying results, especially for the elderly, given the projected increases in both the severity and the frequency of extreme summers in a future, changed, climate. Practical application: This paper provides new data on the performance of the homes of the elderly in both a typical and atypically warm summer. Our results could be considered for building performance evaluation in homes with elderly occupants to mitigate overheating risk. Crucially, we not only examine the impact of CIBSE criteria on these homes but also look at thermal acceptance, which is important to understand the true impact of elevated temperatures in this demographic.