Seasonal variations in thermal comfort: assessing biophysical impacts of green infrastructure in a hot-arid urban setting

Abstract

In historically hot-arid climates like Ahmedabad, the urban environment amplifies thermal discomfort across seasons, with extreme heat dominating summer and a notable drop in wintertime temperatures. These seasonal contrasts highlight the need to evaluate how green infrastructure (GI) affects biophysical conditions and thermal comfort throughout the year. We specifically examine the effects of three GI interventions—green roofs, permeable pavements, and bioretention cells—that are feasible for cities with limited space availability and have been adopted as measures to reduce urban flooding. Our study investigates how these individual GIs influence the thermal responses of diverse population groups during both summer and winter, acknowledging the varied physiological and demographic sensitivities to seasonal extremes. Using high-resolution (3 meters) ENVI-met simulations for representative summer and winter days, we assess the thermal comfort of individuals of varying ages, genders, and social strata, using parameters like clothing insulation, metabolic rate, body weight, and surface area. We also account for seasonal shifts in thermal comfort definitions, where summer emphasizes mitigating heat stress and winter addresses cold exposure. Our results demonstrate significant seasonal differences in how GIs modulate microclimate and influence thermal responses, with implications for equitable urban design. By addressing seasonal and demographic variability, this study provides actionable insights for tailoring GI strategies to improve thermal comfort year-round in hot-arid urban contexts.