Study On Planted Roofs’ Building Energy Efficiency In Xi’an

Nowadays, the society has paid more attention on energy problem. Since China hasbecome the biggest country of energy consumption, its energy consumption onbuildings has caused more problems, such as the heat island effect. Eco-design is aconception which focuses on the impact of environment and energy consumption. Theroof energy consumption accounts for a large portion of the building energyconsumption; there are many ecological design technology on roof at this stage;planted roof, as a typical technology on roof`s energy saving, has eased thecontradictions between urban land and green land, and also has the positive in urbanenvironment`s development. But in cold regions, such as Xi`an, the impact on plantedroof has not attracted much attention.In recent years, Xi`an paid more attention on planted roof`s development. Theparameters on energy saving capability may difficult to determine for the simple greenroof.Planted roof has many positive characteristics, like moisture absorption, waterabsorption, evaporation and opened to climate. It is not a simple heat transfer processbut a process coupled with heat transfer, moisture transfer and phase change. Theinsulation effect is not only hot climate role as the representative of the air temperatureand solar radiation results, and this is to be a wet climate role as the representative ofthe results. Therefore, the energy-saving effect of green roofs is very dependent on thelocal climate.Firstly, starting with analysis of summer climate of the Xi’an area planted roof, plantedroof summer heat process and heat insulation mechanism, Crassulaceae Sedum plantcanopy light planted roof as the object of study of Xi’an a planted roof testing, thermal calculations, the application of heat balance method to quantify the structural layerinsulation performance. Contrast the planted roof roofing insulation effect in summeras well as planting the house to face the impact of the construction of energy-savingeffect calculated planted roof summer equivalent thermal resistance of1.0m K/W.Then, the article starting with the analysis of the winter climate of the Xi’an areaplanted roof, planted roof winter thermal process, Xi’an planted roof in winter testingand calculations, qualitative analysis and quantitative comparison planted roofinsulation performance, calculated equivalent thermal resistance of the planted roof inwinter, combined with the "Energy conservation design standard the calculated lightplanted roof alone can not meet the building winter insulation requirements of energyconservation.The use of natural energy saving energy is the direction of development of thecountries in the world building energy efficiency. In southern China, has been widelyplanted roof for energy saving. Northern China in some areas, especially on behalf ofXi’an, seasonal differences are more obvious, relatively abundant rain, can also be thefull development the light planted roof of this technology as energy-saving approach todevelopment of the building envelope.