Who is most at risk of overheating during heat-periods?

By Mehri Khosravi, Energy and Carbon Senior Research Fellow at the SRI

Climate change is increasing extreme heat events in many regions across the world. The UK experienced record-breaking temperatures, with 2022 and 2023 the two hottest years on record [1].

The health impacts are most common especially among lower socioeconomic groups, as they face barriers in adapting their behaviour to heat. Health impacts are intensified in western countries like the UK where most of the residential buildings are ill-prepared to cope with heat. During the record-breaking heat periods in 2022 in the UK, close to 3000 heat-related excess deaths were recorded in England (excluding COVID-19 deaths), the highest in a given year [2]. A Europe-wide study that compared the mortality linked with the heatwaves of 2022, highlighted the UK’s status among countries with the highest heat-associated mortality [3]. Nearly 85% of heat related mortality occurred in adults 65+ years [4].

The elderly and lower socioeconomic groups are more vulnerable to the impacts of overheating, new research has found. A UK-wide online survey using a questionnaire was carried out by Mehri Khosravi, from the Sustainability Research Institute (SRI) at the University of East London with the University of Bath. The survey investigated the correlation between households’ characteristics on overheating, reported by 1,500 households during a heatwave in 2022. The results show that the experience of heat varies significantly due to a range of factors, including geographical regions, dwelling types as well as socioeconomic factors.

Credit: VladisChern/Shutterstock

Credit: VladisChern/Shutterstock

The result shows the impact of overheating is not uniform across regions in the UK. Overheating is felt most by households located in Greater London three times more than heat felt by dwellings located in other regions such as North-East, and Wales. In addition, household livings in urban areas experience 30oC or above twice as often as households living in rural areas during the 2022 heatwave. In the survey, the difference between overheating experienced by various dwelling typologies showed no huge disparities and overheating was influenced mostly by dwelling age, EPC rating as well as occupancy behaviours and household characteristics. The study concluded that pre-1900 dwellings are cooler than post 1900 dwellings. The prevalence of reported overheating increased in dwellings with an EPC rating A to C compared with dwellings with an EPC rating D to G. This means reported overheating in new homes with higher EPC rating in Greater London could be greater than elsewhere.

UKHSA overheating and social responsibility advice. Credit: UKHSA

Results show that overheating experienced in low-income housing may not entirely rely on the building construction but other socio-technical factors and occupancy behaviours. For example, households age is an important factor that affects overheating experience. Despite older people being often over-represented in mortality statistics associated with hot weather [5], our results show that the self-reported prevalence of overheating is significantly lower for older people. Previous studies highlighted that while 75+ reported less prevalence of overheating, when monitored, rooms in such households were indeed overheating [6]. This could be due to a combined effect of an impaired ability of the elderly in detecting heat [6], and a likely preference for higher temperatures compared to younger people [7]. In addition, some research indicates that older adults aged 75+ years do not perceive themselves as vulnerable and at risk from heatwaves [7]. This low-risk perception of heat is not limited to the elderly. In general, the UK public tend to associate hot weather with ‘good times’ [3]. The British Red Cross warned a cultural shift is needed on heatwave action, as more than a third still don’t consider heatwaves an immediate risk [8].

In addition, the elderly as well as low-income earners are less likely to adopt coping strategies such as investing in cooling technologies. This confirms elderly and lower socioeconomic groups are more vulnerable to the impacts of overheating. While improving public risk perception through risk communication is recommended to mitigate negative health impacts especially on the elderly, more research and policies need to identify and address social inequality under extreme heat.

References:

[1] Met Office, 2024. 2023 was second warmest year on record for UK [WWW Document]. Press Release: 2023 was second warmest year on record for UK. URL

[2] UKHSA, 2022. Excess mortality during heat-periods: 1 June to 31 August 2022.[3] Ravishankar, S., Howarth, C., 2024. Exploring heat risk adaptation governance: A case study of the UK. Environmental Science and Policy. 157. 103761. https://doi.org/10.1016/j.envsci.2024.103761.

[4] Public Health England. Heatwave Mortality Monitoring Report: 2022. Available online at: https://www.gov.uk/government/publications/phe-heatwavemortality- monitoring/heatwave-mortality-monitoring-report-2022.

[5] Hansen, A., Williamson, T., Pisaniello, D., Bennetts, H., van Hoof, J., Arakawa, M. L., et al. (2022). The thermal environment of housing and its implications for the health of older people in South Australia: a mixed-methods study. Atmosphere, 13, 96.

[6] Lomas, K., Watson, S., Allinson, D., Fateh, A., Beaumont, A., Allen, J., Foster, H., Garret, H. et al 2021. Dwelling and household characteristics’ influence on reported and measured summertime overheating: A glimpse of a mild climate in the 2050’s. 201 (15), 107986 https://doi.org/10.1016/j.buildenv.2021.107986.

[7] Williams L, Erens B, Ettelt S, Hajat S, Manacorda T, Mays N. Evaluation of the Heatwave Plan for England. Policy Innovation and Evaluation Research Unit: London, UK. (2019).

[8] British Red Cross. 2023. Cultural shift needed on heatwave action warns British Red Cross, as more than a third still don’t consider heatwaves an immediate risk. https://www.redcross.org.uk/about-us/news-and-media/media-centre/press-releases/cultural-shift-needed-on-heatwave-action-warns-british-red-cross