Abstract:

In this study, we simulated and analyzed the variation of thermal environment and its thermal comfort response on typical winter days in the research area (teaching area in Fuzhou University) using a three-dimensional non-static microclimate model ENVI-met.We also calibrated and verified the ENVI-met model based on a field survey.The results show that the ENVI-met model can well represent the outdoor thermal environment and accurately predict the diurnal variation of air temperature and relative humidity.The daily mean air temperature at the pedestrian's height over concrete pavement and gray brick pavement is 0.1℃ and 0.3℃ higher than that on grassland, and their maximum hourly temperature difference reaches 0.68℃ and 0.65℃, respectively.Building and tree shadows can reduce air temperature at the pedestrian's height by 1.1-1.9℃.The difference of mean radiant temperature (T_mrt) in the same cluster with and without shade can reach up to 30℃.The value of physiological equivalent temperature (PET) near trees and inside building clusters is 2-3 grades lower than that over the hard pavement.In the vegetation-free scheme, the areas with high temperature and low humidity are expanded, and the warming effect in the vertical direction can extend to 10.5 m.Meanwhile, wind speed increases by 1.23 m·s^-1 at the most, the areas with higher mean radiant temperature increase by 69.25%, and the thermal comfort zone and thermal discomfort zone increase by 19.78% and 2.03%, respectively.The research results can favor the urban planning and landscape design for better space construction and greening improvement and can provide some guidance and reference for the optimization of the layout of various underlying surfaces and the selection of vegetation types.

Key words: Microclimate, ENVI-met, Model simulation, Thermal comfort