Research Of Cool Surface Roof In China’s Building Energy Conservation

With the increasingly prominent problems of energy shortage and environmental damage,energy conservation and environmental protection have drawn more and more attention from all walks of life.In China,building energy consumption accounts for about 30% of total social energy consumption,so building energy conservation is of great strategic significance.As an important part of the building envelope,the roof is an important medium for building to absorb solar radiation and exchange heat with the outside world,which means it is also a key object of attention in building energy conservation.First of all,the heat transfer model of cold roof and green roof is theoretically analyzed.The influence of roof solar reflectance,long wave radiance,heat transfer capacity and heat storage capacity on the building load in four climate regions is analyzed by orthogonal design.Energyplus software was used to simulate the impact of green roof leaf area index(LAI),vegetation height,soil layer thickness,soil moisture on building load.Energyplus software was used to simulate the applicability of heat-reflective cold roof,green roof and ordinary roof in different climatic regions in China.The energy consumption under different operating conditions in winter and summer was compared.The results show that the cold roof has the opposite effect on the indoor load of buildings in winter and summer.The use of cold roof in summer can reduce the indoor cooling load and reduce the energy consumption,while the cold roof in winter increases the indoor thermal load and increases the energy consumption Green roofs can reduce building energy consumption throughout the year.And in reducing the temperature difference between the roof surface,cold roof has obvious advantages.In order to verify the correctness of the simulation results,a roof performance test bench was set up in Nanjing.The energy-saving effects of the cool roof,green roof and ordinary roof were measured respectively in summer and winter.The experimental results show the consistency with the simulation results.As the most important points in the key technologies of cold roofs,the mechanism and configuration of solar reflective coatings is analyzed.High-reflective paints of different colors are developed by using aqueous epoxy resin as the base fluid and titanium dioxide & high-temperature inorganic salt materials as pigments.The reflectances is measured by a spectrophotometer,and the energy-saving characteristics are studied by simulation.Aiming at the problem of increasing heat island effect,this paper proposes the secondary saving effect of cold roof and green roof’s energy consumption of building air conditioner by alleviating urban heat island.Through modeling analysis,the effect of different roof technologies on the urban heat island effect in different climate regions was simulated and the double effect of building energy consumption was calculated and analyzed.A comparison between cold roof and photovoltaic roof from three aspects of economy,energy and environment through energy consumption simulation and life cycle assessment is conducted based on the theory of life cycle assessment.A 3-E static recovery period theoretical system based on life cycle assessment was established.The formulas for calculating the static recovery period,the static recovery period of energy and the static recovery period of the environment were given.The case of Nanjing area was calculated.