Assessing thermal comfort for the elderly in historical districts and proposing adaptive urban design strategies: A case study in Zhenjiang, China

Optimizing old urban areas is crucial, particularly in the context of urban aging. These areas typically have a high proportion of elderly residents and require special attention. Thermal comfort significantly influences the utilization of outdoor spaces, yet guidance for urban renewal and design regarding thermal environment improvement remains insufficient. This study focuses on Da Long Wang Xiang (DLWX), a historical district in Zhenjiang City, China, to assess the thermal comfort for the elderly and investigate the urban geometric characteristics that influence it. Both on-site meteorological measurements and numerical modeling were used to observe the variation in the microclimate, and Physiologically Equivalent Temperature (PET) was calculated for assessing the thermal comfort. The findings reveal that the elderly have a higher neutral thermal comfort value, exhibited greater tolerance to heat, and are more sensitive to cold compared to other age groups. Moreover, the factors affecting thermal comfort vary across different street orientations. In NW-SE-oriented alleys, the PET is significantly correlated with the width of alleys (W) and the building height-to-alley width ratio (H/W) in both summer and winter. In NW-SW-oriented alleys, PET is significantly correlated with H/W and the Sky View Factor (SVF) in these two seasons. This nuanced understanding emphasizes the necessity of tailored urban-renewal strategies, thereby contributing to the development of more sustainable and inclusive urban environments.