Evaluating thermal comfort indices for outdoor spaces on a university campus.

This study evaluates the applicability of three thermal comfort indices-Physiologically Equivalent Temperature (PET), Standard Effective Temperature (SET), and Universal Thermal Climate Index (UTCI)-in various outdoor environments on the campus of Xi'an University, China. Meteorological data were collected on sunny days using a portable weather station at a height of 1.5 m, and subjective questionnaires were administered to 25 healthy university students over three months to gather Thermal Sensation Votes (TSV) and Thermal Comfort Votes (TCV). The study was conducted at four distinct outdoor locations: a lakeside area (Location 1), a shaded path (Location 2), a sports field (Location 3), and a plaza (Location 4). PET, SET, and UTCI values were calculated from the collected data using Rayman software. The analysis revealed significant differences in thermal comfort across the four locations, with the highest proportion of subjects feeling hot at the sports field (54.4%) and the highest proportion feeling cold at the lakeside (39%). The shaded path had the highest proportion of subjects feeling comfortable (79.4%), while the lakeside had the lowest (60.1%). The results indicated that SET underestimated thermal sensation at Locations 1, 3, and 4, necessitating calibration. PET was suitable for Locations 2, 3, and 4 but failed to reflect the thermal sensation at Location 1 due to prolonged sun exposure. In contrast, UTCI demonstrated applicability across all locations. To enhance accuracy, revised indices SET' and PET' were formulated using the mean-median method, providing more precise thermal comfort assessments. These findings underscore the limitations of SET and PET under specific conditions and highlight the robustness of UTCI, offering valuable insights for urban planning and design aimed at improving outdoor thermal comfort and well-being.

The difference in thermal comfort between southern and northern Chinese living in the Xi'an cold climate region.

A year-long longitudinal survey regarding perceptions of outdoor thermal conditions and thermal comfort was conducted in Xi'an, a City in a Chinese cold region. The survey included micrometeorological measurements and a longitudinal questionnaire. The thermal comfort and adaptability of southern Chinese (people from Changsha and Guangzhou) and northern Chinese (people from Xi'an) in Xi'an were studied from the three aspects of psychological, physiological, and behavioral differences. The results of similar studies in other regions were compared with those of this study. Regarding psychological differences, northerners were more adapted to Xi'an's climate than southerners, with an expected temperatures of 20.7℃ and 24.1℃ for northerners and for southerners, respectively. Regarding physiological differences, the neutral temperature of the northern population was 22.12℃, while that of the southern population was 21.12℃. The neutral temperature for the southern population in Xi'an is similar to that of northern people living in Xi'an. Regarding behavioral differences, northerners were more likely than southerners to maintain their thermal comfort by adjusting their clothing when they experienced a change in the outdoor environment. This study not only indicates that there were differences regarding the thermal comfort of people originating different regions but also provided support for fully explaining the mechanism of climate adaptation of human thermal comfort. In addition, this work provides basic data regarding formulating outdoor thermal comfort standards and provided data support for personalized thermal comfort.