Contrastive Research On Energy Efficiency From The Application Of Containered Planting Roof And Reflective Roof

National new urbanization plan proposed the objectives that the government should accelerate the existing building energy conservation.Roof is an important building envelope which is influenced by the external environment and one of the main targets of design and retrofit for building energy efficiency.The air conditioners' enery efficiency of the containered planting roof and reflective roof is affected by the the regional climatic conditions.In order to determine the more suitable roof technology for existing office building retrofit in Chonqing,a comparative study on energy efficiency of containered planting roof and reflective roof in a typical office building in Chongqing was launched.Firstly,the climatic characteristics of Chongqing area and the energy consumption characteristics of office buildings were analyzed.The insulation mechanism of the containered planting roof and reflective roof was analyzed based on the roof heat balance theory,and the factors that influenced the energy efficiency of the containered planting roof and reflective roof were studied.Secondly,a typical office building in Jiangjin District of Chongqing Municpal was selected to construct energy efficiency measure platform,and three top-floor rooms which have the same size,construction and orientation were transformed by the sedum lineare containered planting roof,white heat reflective paint roof and gray ordinary paint benchmark roof.The albedo of three types of roof was long-term measured as well as the indoor and outdoor thermal environment parameters and annual air conditioning energy consumption of three top-floor rooms.The measured results show that the airconditioning energy saving rate of the containered planting roof and reflective roof room was 12.6% and 15.1% respectively in comparision with the benchmark roof room.After one year's natural aging,the energy efficiency decreased with the albedo of reflective roof decreasing,and the rate of decline in air-conditioning energy-saving rate was similar to that of the albedo rate.The energy efficiency of containered planting roof was basically stable due to the periodic growth pattern of the plant.Finally,the life cycle cost analysis method is used to study the economic benefits of the existing office building retrofit by the containered planting roof,the reflective roof.The results show that the economic benefit of the reflective was better than that of the containered planting roof.The results of the study provide a theoretical basis for the application of roof energy saving design and energy saving retrofit in Chongqing area.