How campus green space elements differently influence students' thermal perception during transition seasons?

Abstract

Campus green space (CGS) is an important factor in shaping the outdoor thermal environment, which profoundly affects students' thermal perception. In order to explore its influence mechanism with thermal perception twenty-four CGS observations were installed inside Tianjin University. Through measurements and subjective surveys (N = 48), real-time data for six CGS elements, five outdoor thermal environment parameters, and three thermal perception indicators were obtained. By using statistical analysis, the differential influence relationships and mechanisms of CGS on outdoor thermal environment and thermal perception under natural conditions in transition seasons were then quantified. It was found that: (1) CGS with lower weighted height, moderate sky view factor and lower absorption coefficient can create more pleasant outdoor thermal environment and thermal perception. CGS with lower weighted height and higher sky view factor tended to have a more comfortable thermal perception but violent amplitude, and vice versa was more stable. 13:00 to 14:00 was the common node where the best outdoor thermal environment and thermal perception appeared. (2) Weighted height, absorption coefficient, and sky view factor had differential effects on thermal perception by modulating air temperature, surface temperature, relative humidity, and mean radiant temperature. Weighted height was the prerequisite for the overall outdoor thermal environment and thermal perception, with nine pathways and 67.34 % contribution. Mean radiant temperature was the key mediator for the tandem influence paths. (3) It is recommended to control the weighted height around 2.50m, choose materials with moderate or low absorption coefficient values and light colors, and shape the sky view factor consisting of closely planted deciduous trees. These results can provide a valid basis for the integrated improvement of thermal perception during the CGS design process.