Study On The Influence Mechanism Of Urban Commercial And Residential Mixed Street Pattern On Microclimate

With the rapid development of economy and the rapid expansion of cities,the microclimate environment is becoming more and more complex due to various factors,and the living environment of the first tier cities still has much room for improvement.The Beijing's Core Area located in the center of the city has various architectural patterns,rich green space patterns and complex road environment,which can have a direct impact on the urban microclimate.Based on the existing theoretical research results of urban block microclimate,residential microclimate and urban road environment microclimate,this paper classifies the information data of 30 commercial and residential mixed blocks in Beijing.The microclimate data of commercial green space,junction road and community green space in six typical blocks were monitored in summer and winter.The results show that the sunshine radiation is the main factor affecting the site temperature and humidity,the air temperature of community green space is the lowest in summer.In summer and winter,the wind speed of commercial green space is the highest,the wind speed of community green space is the lowest,and the relative humidity of two measuring points is higher.Human factors have the most obvious effect on the particulate matter of commercial green space.The data statistics and correlation analysis by MATLAB show that in the environment of good air quality,there is a very significant negative correlation between air temperature and particulate matter in summer,the correlation between relative humidity and particulate matter in summer is very significant and moderately strong,a weak positive correlation between wind speed and particulate matter in summer,and a weak correlation in winter.Combined with ENVI-met simulation software,the microclimate and comfort of six typical commercial and residential mixed block cases and 15 typical commercial and residential mixed block models are simulated,and the influence of different pattern types on microclimate and comfort is summarized.The specific influence mechanism includes: the shelter of buildings from the sun radiation is the main factor affecting the site temperature,humidity and comfort.Commercial buildings play a leading role in the microclimate environment and comfort of some areas in the block.The shadow of commercial buildings is not conducive to the rapid heating of the site,and the comfort is not good in winter.The effect of moisturizing and windproof of commercial green trees is outstanding,and the effect of cooling and humidifying by planting street trees on both sides of the junction road is the best.The ventilation effect of parallel green space in residential area is the best,and the wind speed of high-rise residential buildings is higher than that of low-rise buildings.The enclosed residential building has the best windproof effect in two seasons and the best thermal insulation effect in winter.Point residential buildings lead to the formation of continuous strong wind area.The larger the green area and the richer the vegetation level,the better the cooling and humidifying effect of the site.The ventilation Corridor around the block can easily lead to the increase of wind speed of commercial green space.At the end of this paper,some suggestions are put forward to improve the microclimate and comfort of the existing mixed commercial and residential blocks.Planting tall trees and multi-level vegetation is the direct means to improve the microclimate of commercial public space.Planting trees with appropriate density and human height on both sides of the junction road is conducive to improving the local comfort,The fine site design of community green space landscape sketch and vegetation is an important guarantee for high-quality activity experience.At the same time,it provides ideas for future urban design,such as strictly controlling the volume of commercial buildings,appropriately increasing the area of commercial green space and vegetation level,planting roadside trees on both sides of the junction road as far as possible,fully lighting the main activity sites in the residential area,and planting arbors and shade resistant vegetation in the residential buildings and public space,The enclosed vegetation planting mode is conducive to the improvement of local comfort.Finally,the future research methods of urban microclimate are prospected.