Research On The Cooling Effect Of Vertical Greening On Buildings

The greening is an essential way to improve the urban ecological environment. The vertical greening exhibits significant effects on decreasing the room temperature in summer. The existed researches on the thermal effects of the vertical greening are mainly focused on the studying of the greening method and the experimental observation of the temperature variation. However, the relevant computational simulation and prediction of the thermal effect of the vertical greening are lacked. The present thesis focuses on the computational simulation of the thermal effects of the vertical greening. The main work of the present thesis are listed in details as follows,1) A brief introduction of the development of the vertical greening in various countries and regions were presented. The plant species of vertical greening and its installation method were introduced. The advantage and disadvantage of different installation methods were reviewed basing on physics principles and published literatures.2) The analysis method of the heat conduction in vertical greening was established. The heat conduction relation between plant layer, ground, building and air was analyzed. The differential equations including the heat exchange equation and the heat conduction equation of building materials were proposed. The differential equations can be solved to simulate the cooling effect of the vertical greening by the commercial or homemade finite element software under certain boundary conditions.3) The temperature evolution of the building model under solar irradiation was simulated by COSMOL finite element method software package. Firstly, the temperature of concrete surfaces with and without vertical greening covering was calculated. Then, the simulation results about a closed concrete building model show that the vertical greening can decrease the room temperature up to 4℃ at noon in summer. To reveal the cooling effects of vertical greening in different time,17 sets of temperature data with and without the vertical greening were calculated, in which the time range covers from 8:30 am to 16:30 pm. Based on the above results, the energy consumption benefit of the vertical greening was evaluated.4) The outdoor cooling effect of the vertical greening was calculated with ENVI-met software package. The weather condition of an area with six concrete building models was simulated. The temperature, wind speed and humidity in the model area at noon were calculated with and without the vertical greening. The law of the effect of vertical greening on the outdoor temperature is quite obtained.