| With the acceleration of urbanization in China,the natural underlying surfaces of residential areas have been replaced by artificial pavement such as bricks and asphalt pavements,which results in increasing urban heat island and residential thermal environment degradation,endangering the physical and mental health of residents,thus increasing the energy consumption in residential buildings.The thermal performances of underlying surfaces have a significant impact on the thermal environment.In this paper,the research on the thermal environment of the Chongqing residential area is conducted with a combination of field observation and numerical simulation.The main works and conclusions are as follows:Firstly,an existing residential area in Chongqing was taken as the research object,the outdoor thermal environment and underlying surface status of the residential area were investigated and measured in July 2018 and January 2019.The results showed that blue spaces and green spaces had significant cooling effects on the microclimate of the residential area in both winter and summer,while asphalt and concrete had heating effect in reverse.In summer,the mean surface temperatures of lawns,shrubs,and trees decreased by turns,for the hardened pavement,the surface temperatures of asphalt,concrete,pebbles,coated gravel,granite,and pebbles decreased by turns;while the surface temperatures of underlying surfaces were not significantly different in winter.Secondly,the spatial and temporal distribution characteristics of temperature and humidity of asphalt road,brick road,lawn,shrub,tree and water body in summer residential area were measured,as well as the vertical structures near the grounds of them,and then the correlations between temperature,humidity,solar radiation and wind speed of meteorological station was investigated.The results show that the air temperatures near the ground of each underlying surfaces generally show a trend of rising at daytime and falling at night.The air temperature near the ground of asphalt road is the highest,followed by masonry road,and the air temperature near the ground of trees is the lowest.There are no significant differences in air temperature and humidity in the vertical direction between brick road and asphalt road,but there is obvious temperature stratification in water body,tree,and shrub,and the air temperatures of the ground near water body and tree rises as the height increases,while absolute humidity decreases in reverse.Thirdly,based on the theory of fluid mechanics and heat transfer,the regional model of the residential area in summer is established by using N-S equation and radiation model,and the verify of the simulation results is conbducted.Finally,based on ENVI-met software platform,the verified regional model has been used to optimize and analyze the parameters of reflectivity,specific heat capacity,thermal conductivity,and permeability of underlying surfaces of the residential area in Chongqing in order to create a livable environment.The results show that the outdoor temperature of the residential area can be effectively improved by greening,laying permeable bricks and improving the reflectivity of the underlying surface.The underlying surface with large specific heat capacitycan can reduce the daily average temperature of the residential area,and the cooling effect is more obviously in daytime than at night.Additonally,the underlying surface with large thermal conductivity can enables the change of near-ground temperature lagging behind,but it cannot improve the thermal environment significantly.Moreover,the effect of improving the reflectance and specific heat capacity of the underlying surface are more remarkable than that of only improving a single factor.After optimization,the daily average temperature of residential area decreases by 1.0 ? and the maximum temperature decreases by 2.4 ?.In conclusion,the reasonable selection and layout of the underlying surface parameters can provide a suitable reference for outdoor thermal environment planning. |
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