Analysis Of The Influence Of Block Space Morphology On The Spatial And Temporal Distribution Of The Thermal Environment Of Street Canyons In Summer

With the continuous acceleration of the urban process and the rapid expansion of urban areas in our country,various types of urban climate problems caused by extensive development are becoming increasingly prominent.The deterioration of the urban climate will inevitably affect the thermal environment of street canyons,which are important space for daily activities of residents.The harsh thermal environment of street canyons will reduce the quality of life of residents.It is important to analyze and compare the characteristics of thermal environment of street canyons under different spatial forms in different cities with the help of interdisciplinary study,and put forward corresponding optimization guidance.Based on the above background,this paper adopts the field movement measurement method,taking a total of ten typical urban blocks in three different climatic regions in Guiyang,Zhengzhou and Wuhan as the research objects to collect air temperature in different streets canyons in summer afternoon and night and spatial morphological indicators.Due to the climatic differences in different cities and the air temperature fluctuations during the actual measurement period,it is not possible to use air temperature for comparative analysis directly.This article defines a new thermal environment assessment index,namely the regional air temperature change rate for analysis.Then,the spatial morphology of the measured plots is classified from the two aspects of land use intensity and building layout.The multiple linear regression analysis method was used to verify that the spatial morphological indicators such as impervious ground rate,average sky view factors,aspect ratio,area ratio,and density had significant correlations with ATCR in street canyons of different intensity types.Then select three big categories and ten small categories,with a total of seventeen sample cases,to analyze the spatial morphological characteristics of streets,the distribution characteristics and impact mechanism of the continuously thermal environment in street canyons.It is found that due to the comprehensive impact of urban spatial morphology,there is no significant difference between the thermal environment of street canyons in different urban blocks of land use intensity;the horizontal partial form of buildings along the street canyons,the degree of vertical space interface enclosure,and the relative relationship between street canyon orientations and the prevailing wind direction in cities have great impacts on ventilation and heat dissipation in street canyons;In the north-south street canyon,higher aspect ratios and lower average sky view factors can usually block part of the solar radiation that gets directly into the street canyons,while in east-west street canyons,lush street trees need to be planted to make up for the defects that building shadows that cannot be cast in street canyons;in street and square urban areas,streets often have better ventilation conditions,and outside air can be introduced to help heat dissipation in the street canyons,while street orientation has more impacts on the thermal environment of street canyons in enclosed urban areas.Finally,this paper summarized three levels of measures from urban planning,building design and detailed design to optimize thermal environment of street canyons.It can be concluded that comprehensive use of these suggestions according to the climatic conditions in which the urban area is located can effectively improve the thermal environment of urban street canyons.