The effect of environmental attributes on microclimate and thermal comfort in an urban park

Urban heat island effect enhances with the rapidness and intensity of city development. With the increasing density of traffic and construction, urban parks become an important space in people’s daily life. The aim of this study is to investigate the effect of environmental attributes on microclimate and thermal comfort in an urban park. The environmental attributes include species of trees, shading degree, ground type and distance from waterscape. Considering the spatial distribution of different species of trees and different environmental characteristics, 71 zones in Daan forest park were selected, and a total of 19 species of trees were included in the study. Microclimate was measured by a weather station and the variables air temperatures, relative humidity and wind speed were obtained；ground surface temperature was measured by a thermal image camera. Thermal comfort assessment and personal characteristics were investigated by a structured questionnaire. Thermal comfort assessment included the factors thermal perception, comfort and acceptability. Personal characteristics included age, activity type, activity duration and clothing. Our study collected 414 valid samples. The results revealed that the species of trees, ground type and shading degree had significant influences on relative ground surface temperature, the higher the shading degree the lower the relative ground surface temperature. Different zones, species of trees, shading degree and ground type had significant influences on average relative air temperature, average relative humidity and average relative wind speed, the higher the shading degree, the lower the average relative air temperature and the higher the average relative humidity. In thermal comfort assessment, the higher the air temperature, the hotter the people feel, and the lower the comfort and acceptability. The higher the relative humidity, the cooler the people feel and the lower the acceptability. In personal characteristics, age, activity type and clothing (clo) had significant influences on thermal perception, comfort and acceptability, the higher the clo value, the more uncomfortable the people feel.