Adaptive thermal comfort in urban parks across temperate and subtropical climates

Rapid urbanization has significantly reduced urban green spaces, intensified the urban heat island effect, and increased concerns regarding outdoor thermal comfort and public health. Urban parks play a crucial role in supporting recreation and human well-being. This study addresses the lack of field based evidence linking microclimatic conditions and human thermal responses in urban parks within rapidly urbanizing cities, using Kathmandu and the Rupandehi district of Nepal which are located in temperate and sub-tropical climate respectively. A total of 1,119 visitors were interviewed in shaded areas of urban parks in two districts to obtain thermal comfort votes, accompanied by simultaneous microclimatic measurements conducted over 35 days during the daytime of summer season. The results showed that 50.6% of respondents in both temperate climate (N = 868) and the subtropical climate (N= 251), perceived the environment as “Slightly hot”. The 80% upper limit of thermal acceptability for Physiological Equivalent Temperature (PET) and Universal Thermal Climate Index (UTCI) of sub-tropical climate were29.6 °C and 32.0 °C which are 2.6°C and 2.7°C higher than temperate climate. The comfort PET and UTCI values of sub-tropical climate were 29.8 °C and 32.2 °C which are 4.7°C and 4.6°C higher than temperate climate respectively. An outdoor adaptive model for shaded spaces in urban park was developed for both climates. This study provides benchmarks for climate-responsive shaded urban park design and offers actionable insights for urban planners to mitigate thermal stress in rapidly urbanizing cities.