| China’s building energy consumption and urban environmental problems have become more serious in the 21st century. National regulatory authorities continuously increase the energy conservation requirements of the construction, and pay more emphasis on energy-saving design of the building. However, the current building energy-saving studies focus on simple energy-saving equipment or a type of building materials. So when making energy efficiency and environmental quality analysis, the study doesn’t take the building and its external environment as integrated to make a systematic analysis of energy efficiency and environmental quality.Green roofing is a passive building technology. In "Green Building Rating Standards" issued by Ministry of Construction, the usage of green roof is a preferred item in "energy-saving and energy use" section in public building. By using additional green roof layers, it improves the thermal performance inside the building, it also increases the green area of the city of the building roof layer outside the building. These dual effects can reduce energy consumption inside the building, and relieve urban heat island effect outside the building. Green roof technology can be applied to both new construction and construction built before and still in usage. Extensive green roof is a low cost and widely used technology in green roof technology.In the middle and lower reaches of Yangtze River, weather in winter and summer go to extremes and is always humid and rainy all year round. Humidity is relatively high outside the room. Summer tends to be steaming hot and damp and winter is moist, chilly with low-quality air. The application of green roof technology in such climate, the selection of green roof construction and green plant should be made based on the climatic characteristics.In this paper, considering extreme weather conditions during diverse seasons in the middle and lower reaches of Yangtze River, the application of open roofs influence on building environment was studied. The study mainly involved the design technology, construction of internal energy consumption of the construction, analysis of external building environment. At the beginning of this paper, the existing green roof design, roof type and its application were introduced, and the existing scientific literature was overviewed. Then basic principles of heat transfer in the green roof were analyzed. After that, energy saving effect of the green roof was verified by experimental monitoring and energy simulation. To prove the green roof effect on energy consumption of building, the temperature of a model office building in Nanjing City was monitored, temperature distribution in green roof and general roof in real-time were recorded, and the actual measured results and results simulated by EnergyPlus energy consumption software were compared and analyzed. From the perspective of green roofing application, PKPM simulation software was used to simulate the energy efficiency of different types of green roofs. To demonstrate the impact of green roofing to the external environment, Airpak simulation software was used to simulate the effect on the environment in a residential area in Shanghai after the application of green roofs. Then the impact of green roof on external environment in terms of temperature and radiation are analyzed. The end of the paper made a summary and points out the deficiencies of this study. |
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