Understanding thermal comfort expectations in older adults: The role of long-term thermal history

Abstract

Understanding how long-term thermal history affects thermal comfort expectations in older adults (65+) has implications for designing energy-efficient spaces in a changing climate. A growing number of studies focus on thermal sensation/preference votes to represent the current thermal comfort expectations, often overlooking their limitations. This study, however, investigates how factors shaping long-term thermal history link to the current 65+ adults indoor thermal comfort expectations during exposure to heat, by focusing on the upper limit of thermally acceptable temperature range, represented by a self-reported temperature threshold at which 65+ adults believe to feel uncomfortable by indoor heat (Tit). To find Tit, we use answers to “Above what temperature do you start feeling too hot indoors?” by survey respondents in Warsaw (n = 678) and Madrid (n = 527), who lived in their apartment ≥5 years. Statistically, we find indoor factors affecting long-term thermal experiences more significant in explaining 65+ Tit, when compared to outdoor factors such as distance to water, vegetation, or surface thermal radiance. Better-insulated buildings were associated with a lower Tit (p < 0.05), suggesting a higher thermal sensitivity of such building residents to heat. Our key findings indicate for normal housing units’ area (∼80 m2), personal factors such as Basal Metabolic Rate (main effect 95% CI = +0.42 – +2.6 °C) and health status (+0.11 – +1.68 °C) were associated with a higher 65+ Tit and lower thermal sensitivities to heat (p < 0.05). Findings shed light on the complexity of factors shaping indoor thermal comfort expectations among 65+ adults.