Correlation Between Summertime Urban Canopy Temperature And Spatial Morphology In Northern Urban Commercial District

As a main activity place of the city,thermal comfort in business district has been paid more attention in resent years.Present research on correlation between urban morphology and thermal environment have got certain progress,but research focusing on business district is still in the stage of start,due to its own spatial morphological characteristics.There is need to explore more suitable for the thermal environment of urban morphology characteristics observations and morphological index quantitative method.Taking Taiyuan business district as an example,Envi-met was used to simulate the thermal environment in summer,and then the correlation between urban spatial form and thermal environment was analyzed.Specific steps included:(1)Built the urban model of the research area based on the field survey and elevation map,and analyzing its spatial morphology characteristics from the aspects of construction intensity and building layout;(2)Envi-met was applied for numerical simulation to analyze the overall temperature distribution in the study area and the temperature variation range in different scales was compared;(3)Carried out a quantitatively study the correlation degree between urban form indexes and air temperature by regression analysis,determining the optimal correlation range between each index and air temperature,and analyze the local temperature fluctuations caused by building layout;(4)Based on the above conclusions,the paper proposes optimization strategies for thermal environment for different urban design problems.The main conclusions of the study are as follows:(1)The construction intensity of Taiyuan business district presents strong unevenness in both horizontal and vertical directions,and the architectural layout is diversified and the spatial form is changeable.(2)At noon,the hot area was generally distributed on the windward side of the building without shading,while the cool area was generally distributed on the shadow area on the leeward side of the building.The maximum temperature difference within the urban scale can reached 1.63℃,and the average temperature difference of the plot reached 0.56℃ when the local construction intensity is the same.Spatial temperature difference within the area scale decreases.Air convection in micro-scale showed a greater influence on the temperature than solar radiation did.Temperature difference around buildings caused by solar radiation only recorded 0.08-0.33℃,but 0.32-0.74℃ by convection,and 0.65-0.96℃ by the combined effect.(3)Building density and building height showed the strongest correlation with air temperature.The highest temperature decreases with the increases of building height,and decreases first and then increases with the increases of building density,and is negatively correlated with the enclosing degree,but not significantly correlated with the sky view factor.The smaller the angle between the axis and the wind direction,the higher the temperature.(4)There are different morphological factors that affect air temperature in different scales.Urban design above the medium scale should first consider the control of construction intensity index,and micro-scale architecture and urban renewal design should use more means such as optimizing building layout and plant landscape to improve microclimate.