Thermal Indices for Urban Climate Walk Measurements and Simulations

Abstract

Thermal variability is essential for assessing outdoor thermal comfort and walkability in urban areas, as it provides thermal-adaptive and alliesthesial opportunities along a walk. This is evidenced by temperature fluctuations that promote passive, intermittent cooling and warming through radiation, convection, and evaporation among buildings, trees, and water bodies. These cooling and warming spots facilitate thermal recovery for pedestrians, as reflected in their metabolic rate, skin and core temperatures, and sweat productions. This paper investigates dynamic thermal comfort along a 3.6 km walk in Rome, Italy, using mobile measurements and simulations (ENVI-met, BIO-met, and Rayman) to explore dynamic thermal indices for forecasting thermophysiological changes due to sun and wind. Two novel thermal indices, 𝑑𝑃𝐸𝑇 and 𝑚𝑃𝐸𝑇, were compared with the static PET maps under non-extreme (September 2021) and extreme (July 2022) weather. The results indicate that both indices capture the temporal progression of environmental and personal parameters. However, they exhibit distinct spatial-temporal patterns owing to their sensitivity to fluctuating thermal conditions. The discussions highlight the need for further lab and field thermophysiological studies to improve dynamic thermal indices for urban climate walk simulations.