Cold Island Effect Of Roof Greening And Coupling Simulation Of Air-Conditioning Load In Hot And Humid Area

Roof greening is an important part of urban greening,and its cooling effect is helpful to alleviate urban heat island and reduce building energy consumption.Taking Nanning,a representative city in hot and humid area,as an example,this paper studies the effect of roof greening on building outdoor thermal environment at block scale,and discusses the effect of roof greening design factors on cold island effect and the effect of cold island effect on building air conditioning load.Firstly,the influence mechanism of roof greening on the thermal environment of street canyons was explained based on the energy balance principle of street canyons.According to the above mechanism and the main design factors considered in the scheme stage,the design factors that may affect the cold island effect of roof greening are selected,and the numerical simulation method is proposed to analyze the influence degree.The calculation method of air conditioning load considering cold island effect is studied.Second,an outdoor thermal environment simulation method based on ENVIMET software is proposed and verified.The effectiveness of the simulation method is verified by the comparison with the measured data.The mean-square error(RMSE)between the simulated value and the measured value is not greater than 1.42℃,and the consistency index(D)is not less than 0.90.Thirdly,the influence of roof greening design factors on the cooling intensity of cold island effect is studied by the above simulation method.The working condition design of single building and group building is carried out by orthogonal test method.Through the orthogonal experiment of 36 kinds of working condition of data analysis showed that the monomer architectural design factors be order in the first three: form > building roof greening coverage > building height,which was positively related to the intensity of cold island effect cooling factors for roof greening coverage,building height,back to the glyph cooling intensity biggest building form;In order of the significance of group building factors,the top three are: roof green coverage rate > green layout form > building height.The factor that is positively correlated with the cooling intensity of cold island effect is roof green coverage rate,and the point layout has the highest cooling intensity.Fourthly,a fast calculation method of cooling intensity of nanning cold island effect is proposed,and a parameterized coupled air conditioning load simulation platform is built.Taking the roof green coverage rate,green layout form and time as variables,the multi-factor combination simulation was carried out,and a fast calculation method of cold island effect cooling intensity of single building was obtained through multiple regression analysis.A coupled simulation platform was set up in RH&GH software,and the outdoor air temperature was corrected by a fast calculation method of cold island effect cooling intensity,and the air conditioning load was simulated based on Energy Plus.The simulation comparison with ENVI-MET showed that the root mean square error(RMSE)and consistency index(D)of the formula for rapid prediction of cooling intensity were not higher than 0.006°C and 0.930,which could meet the requirements for calculation of cooling intensity and air conditioning load of roof greening cold island effect at the scheme stage.