Climate change is intensifying the frequency and persistence of extreme heat events, raising concerns about indoor thermal conditions in residential buildings across diverse climates. While overheating has traditionally been associated with warm climates, recent evidence indicates increasing vulnerability in temperate and cooler regions under future warming. This study examines indoor overheating and heat-health-related exposure in existing residential buildings across European and Middle Eastern climate zones using a multiple-case comparative simulation approach. Five residential case studies were analysed under a current baseline climate and six future scenarios (2035, 2065, and 2090) based on RCP 4.5 and RCP 8.5. Indoor conditions were assessed using operative temperature and a set of indicators capturing multiple dimensions of indoor heat exposure, including threshold exceedance (>26 °C, >30 °C, >35 °C, >40 °C), maximum consecutive hours above 30 °C, nighttime exposure, and peak indoor temperatures. The results show a consistent increase in overheating across all climates, accompanied by a shift toward higher temperature thresholds and more persistent exposure patterns. Heat-health indicators reveal longer durations of continuous overheating, elevated nighttime temperatures, and higher peak indoor conditions, indicating reduced potential for thermal recovery. The findings demonstrate that future overheating is characterised not only by greater frequency but also by increased severity and persistence across climate zones. The study contributes a comparative, exposure-oriented framework for assessing indoor overheating and supports the integration of heat-health considerations into residential climate adaptation strategies.
Samaro et al. (Wed,) studied this question.