Outdoor thermal comfort of university students and space design strategies for alleviation: A case study in Xi’an

The rapid expansion of university scales and the growth in numbers of students make the health of university students increasingly significant. Students' health has been reported to be adversely affected by the lack of outdoor activities that were critically determined by thermal comfort . This study explores the thermal comfort of students in outdoor spaces at university in Xi'an, China, using the Universal Thermal Climate Index (UTCI) to evaluate their thermal environment and suggest bioclimatic design interventions for these spaces. Four main findings were obtained 1) The significant meteorological influences on students' thermal sensations differ across different campus open spaces. In HB (Hongqiao sinking space) spaces, relative humidity (RH) and air temperature (Ta) are key influences; in CS(College Activity Square) spaces, solar radiation (G), globe temperature (Tg), and wind speed (Va) are predominant; in JG(Jinqiao space) spaces, Ta, Tg, and Va are crucial; and in SH (Sport hall square) spaces, the combination of Ta, Tg, Va, and RH are dominant. 2) During the summer, there is a notable variation in thermal comfort benchmarks across the campus areas. The Neutral UTCI (NUTCI) recorded are 20.34℃ for HB, 23.61℃ for CS, 26.13℃ for JG, and 17.11℃ for SH. Corresponding NUTCI ranges (NUTCIR) are 15.21-25.47℃ for HB, 18.31-28.91℃ for CS, 21.27-30.98℃ for JG, and 12.94-21.27℃ for SH, respectively. 3) Variability in thermal sensations exists even within the same climatic zone across different campus spaces, necessitating tailored designs for thermal comfort. 4) We propose bioclimatic design solutions such as the introduction of vegetation, shading structures, sprinkler systems, and improved paving to enhance comfort in these outdoor settings. These proposals are aimed at guiding planners and landscape architects in optimizing the design of these spaces, thereby enhancing students' outdoor activity levels and promoting their physical and mental health.