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

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 (T it). To find T it , 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+ T it , when compared to outdoor factors such as distance to water, vegetation, or surface thermal radiance. Better-insulated buildings were associated with a lower T it (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+ T it 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. • Building, environmental, socio-economic, and demographic factors are considered. • Better building insulation is linked to an increased thermal sensitivity to heat. • A high Basal Metabolism Rate correlates with a reduced thermal sensitivity to heat. • Better Health Status correlates with a reduced thermal sensitivity to heat. • Factors affecting indoor thermal experiences are more significant than outdoor ones. [ABSTRACT FROM AUTHOR]