Study On The Effect Of Roof Greening On Building Thermal Environment In Xi'an

In recent years,the process of urbanization has been developing rapidly in our country,a large number of rural population is pouring into the city,and the buildings are developing towards a higher and more intensive trend,causing some ecological problems,such as heat island effect,urban Haze and building energy consumption.Relevant research shows that green plants play a key role in beautifying urban environment,controlling air pollution,improving heat island effect and so on.At the same time,people who live in cities are gradually tired of reinforced concrete buildings,yearning to return to nature and enjoying natural life.In this context,here comes the roof greening.The roof greening,as a unique form of urban greening which expands into three-dimensional space,exploits green space and enlarges urban greening sphere,has been gradually recognized by people and rapidly developed in China's urban construction.In order to study the effect of Roof Greening on Building Thermal Environment of in Xi'an,investigation method,field experiment method and simulation method are adopted in this study.Firstly,taking the urgency and feasibility of developing roof greening as a start,the importance of developing roof greening is expounded.Through the investigation of existing green roof in Xi'an,twenty-five representative green roof are selected to conduct field investigation,and then types of green roof,suitable plants and construction situation of green roof in Xi'an are summarized.Based on that,the existing problems and suggestions on the green roof of Xi'an are proposed.Secondly,four different types of green roof are selected for the thermal environment test.There is the conclusion from indoor thermal environment test: The effect of garden green roof on indoor thermal environment is better than that of lawn green roof,and garden green roof is better on the stability of indoor thermal environment.The conclusion of outdoor thermal environment test: the range of influence and effect of green roof on the vertical and horizontal thermal environment has to do with the configuration of plants.The configuration of “trees + shrubs” has a large influence on the temperature and humidity of the vertical direction;the configuration “shrubs + lawns” has a larger influence on the temperature and humidity of the horizontal direction.Finally,a numerical model of green roof is established and indoor thermal environment simulation is carried out using Energy plus,which aims to explore the influence of different types of green roof on the indoor thermal environment of building's top floor.At the same time,the optimum factor that affects the inner surface temperature of green roof is studied through orthogonal test.The outdoor thermal environment simulation is carried out using Envi-met to explore the effects of different plant configurations and different layout form on outdoor thermal environment.Through the study on the indoor and outdoor thermal environment of different types of green roof in Xi'an,the effect and scope of the green roof's function on indoor and outdoor thermal environment are summarized and the theory of the green roof's influence on indoor and outdoor thermal environment is perfected.Some beneficial explorations are conducted and references and suggestions are proposed which aims to promote the application of eco-energy conservation technology and the practice of the roof greening in Xi'an.