Coupling Mechanism And Optimization Regulation Of Block Morphology And Microclimate In Typical Urban Central Area Of Plain In Cold Zone

With the progress of urbanization,the urban center has a high concentration of population and a high density of urban space layout,leading to a series of urban microclimate problems such as poor outdoor ventilation,low thermal comfort,and declining air quality.The formation of urban microclimate is not only influenced by macro climatic factors,but also closely related to urban morphology.Urban block is the basic unit of a city,different forms and interfaces of the block,its internal space heat transfer characteristics must be different,thus showing different microclimate characteristics.Block scale microclimate is an organic component of the whole urban microclimate.In terms of improving the urban microclimate,good urban block morphology design can improve the ventilation condition,adjust the outdoor temperature and alleviate the urban microclimate problem.In recent years,due to the acceleration of urbanization,the block morphology in the central area of the plain city shows a high density and complex and diverse block morphology characteristics.These changes in the block space make the urban micro-climate problem increasingly prominent.Even in the plain cities in cold zone,there are serious summer heat problems in the urban center.Therefore,this paper focuses on the coupling mechanism and optimal control of urban morphology and microclimate in typical plain city center block scale in cold zone.This paper carries out research from the following three aspects:First of all,by combining qualitative description of types with quantitative description of indicators,the author tries to make a comprehensive summary and accurate description of the urban block morphology in plain cities in cold zone.In qualitative type description research,the author referred to the research method of morphology,typology,take the architectural function and capacity of the combination of subject classification,on the basis of Shi Jia Zhuang,Zheng Zhou and Xi'an three typical case 1000 mx1000m Block slice research unit of the sample,the block morphology of the urban center of plain cities in cold zone was classified and sorted out,found out the three categories(13subcategories)Block Morphology Type(BMT).In the quantitative indicator description research,on the basis of the applicability of the index description,the convenience of index calculation and the operability principle of the inclusion specification,the authors analyzs the formation factors of urban microclimate at the block scale and selects eight quantitative indexes,including building function miexed model,building density,plot ratio,average sky-view factor,average ratio of frontal area,average building height,street form index and ratio of green space,which are used to describe the block morphology of the urban center of the plain city in the cold zone.Secondly,the author analyzed the coupling mechanism between block morphology and urban microclimate by combining field measurement and numerical simulation.After verifying and calibrated the reliability of the numerical simulation results of ENVI-met,an urban microclimate simulation software,based on the field data measured on typical summer days in Zheng Zhou.The author took the typical models of 13 block types in the urban center of plain in cold zone as samples,the influence of block morphology on microclimate was analyzed by ENVI-met software,and a series of correlation between the microclimate index of 1KM~2 block and the quantitative index of block morphology in the urban center of a plain city in cold zone were found.Based on the numerical relationship between block morphology and microclimate,the author reveals the coupling mechanism between block morphology and microclimate in the urban center of a plain city in cold zone from two aspects:the influence mechanism of block morphology on microclimate and the building of block morphology design with comfortable microclimate.It has been proved that the main reason for the high temperature of the block morphology in the urban center of the plain city in cold zone in summer comes from the comprehensive influence of the block space form and its space interface properties.To construct a comfortable microclimate,the design of block morphology should start from the space form and its interface properties.Finally,the author based on the analysis of the coupling mechanism between block morphology and microclimate in urban center of a plain city in cold zone,according to the principle of controlling"heat gain"and accelerating"heat dissipation",summing up the block form control method of improve the high temperature in summer,and use the ENVI-met software simulation to compare the contribution rate of various control methods to reduce the summer outdoor temperature,to obtain the following results:(1)The control method of taking the East-West dislocation layout of block buildings,the cooling effect is good in the commercial block,but poor in the commercial and residential block;(2)The control method of reducing the windward area of buildings in the main wind direction in summer is adopted,the cooling effect is good in commercial residential block and residential block,but poor in commercial block;(3)The control method of increasing the height of the northernmost row of buildings in the road enclosure,the cooling effect is medium in commercial and residential blocks,but poor in business blocks;(4)The control method of increasing the ratio of height to width of the average street,the cooling effect is excellent in commercial and residential blocks,but poor in business blocks;(5)The control method of increasing the green area and the number of trees in the block space,the cooling effect is excellent in all block types;(6)The control method of improving the surface albedo of the block and the outside surface of the building,the cooling effect is excellent in the block with plot ratio>3.5 or building density>30%;(7)The control method of only improving the surface albedo of the block,the cooling effect is excellent in the block with plot ratio?3.5.This paper systematically explores the coupling mechanism and optimal regulation method of block morphology and microclimate in the urban center of a plain city in cold zone,and its conclusions are expected to provide useful references for planners,architects and managers,and contribute to urban block design and architectural design in the urban center of a plain city in cold zone.