Research On Vertical Greening Design Based On Thermal Environmental Benefit In Guangzhou Area

With the acceleration of urban construction in China,the contradiction between urban heat island effect and land use is becoming more and more prominent,which seriously affects people's life and health,daily life and indoor environment comfort.As one of the ways of urban environment greening,architectural vertical greening can not only expand the area of urban greening to alleviate the urban heat island,but also improve the indoor environmental quality of buildings,and play an important role in regulating the indoor comfort.Therefore,this paper takes architectural vertical greening as the research object,and carries out the following research:Firstly,the thermal environmental benefits of architectural vertical greening are summarized.The regulation mechanism can be summarized as four aspects:shading effect,cooling and humidifying effect,heat insulation effect and wind control effect.An evergreen shrub plant——Schefflera octophyyla(Lour.)Harms in Guangzhou area were selected to build a vertical green wall with planting box in the southwest wall of the experimental room,and the vertical greening room and the contrast room were used as the experimental objects.The basic experimental scheme and classification experimental scheme of vertical greening of buildings are designed.Secondly,the field measurement of vertical greening wall is carried out in sunny and hot weather to explore the influence of architectural vertical greening on thermal environment benefit.The experiment consists of three parts,including preliminary preparation experiment,basic experiment and classification experiment.According to the results of the preliminary preparation experiment,the LAI of vertical greening wall is 2.701 m~2/m~2 by harvesting method.When there is no vertical greening wall,the two experimental rooms have the same thermal performance and the error is less than 5%.The results of basic experiments show that architectural vertical greening has better thermal environmental benefits.During the day,the architectural vertical greening shows a remarkable effect in shading,cooling,humidifying and heat insulation,and the heat is transferred from indoor to outdoor.At night,the architectural vertical greening has a thermal insulation effect on the wall and indoor environment,which can reduce the temperature difference between day and night.Soil volume moisture content is positively correlated with heat flow rate.Increasing soil volume moisture content in culture substrate layer can enhance the cooling and heat insulation effect of wall.The results of classification experiments show that the effect of natural ventilation and PGC on thermal environment benefit is higher than that of layout mode.With the increase of PGC,architectural vertical greening gradually becomes stronger in shading,cooling,humidifying and heat insulation effect,while the difference of wind control effect is small.Natural ventilation can promote the effect of vertical greening on indoor cooling and humidification and wall cooling and heat insulation.The maximum indoor air temperature is35.5?,and the maximum heat flux of the inner surface is about 1.5W/m~2.Although the layout mode has little influence on the thermal environment benefit,the four regulation mechanisms can be analyzed synthetically,and the ranking can be:horizontal>dotted>vertical.Then,the paper uses orthogonal test method to take the effect of cooling the wall surface and humidifying outside as the test index,and uses ENVI-met to carry out numerical simulation study of architectural vertical greening,quantitative analysis of PGC,LAI,air interlayer width and composition of the impact on the test index.The study shows that PGC is the most priority factor in vertical greening design of buildings.Its contribution rate to the cooling of the wall surface is over 95%,while the contribution rate of outdoor humidification can be as high as78.6%.LAI was the second,and the contribution rate to outdoor humidification was as high as36.4%,which was much higher than that of wall surface cooling.Air interlayer width and composition mode have little effect on two indexs,and the wall surface cooling is about 0.1?.A multivariate linear model between the test factors and the two test indexes was established by using SPSS software for stepwise regression analysis of PGC,LAI and air interlayer width.the correlation between the test factors and the model and the goodness of fit of the model were tested.Finally,according to the characteristics of humid and hot climate in Guangzhou and the requirements of architectural design,the design method of architectural vertical greening based on thermal environment benefit is put forward by synthesizing the results of experimental measurement,simulation research and regression model analysis.