Theoretical And Experimental Study On Building External Shading Coefficient In Shenzhen

Hot summer and warm winter region in China has a long summer, the air-conditioning energy consumption because of the solar heat gain in summer accounts for 30% to 40% of the total air conditioning energy consumption. The building external sunshade is an efficiency measure for Shenzhen and the whole south of China. But our current shade research is still in the initial stages, particularly there is not in-depth study on the energy-saving effect of the complex shading component emerged in recent years, and there is not understanding for the real effect of shading devices. The research on building energy-saving feature of sunshade devices and evaluation criteria will supply effective reference for improving existing design standards and external shading performance testing evaluation, and provide scientific methods and basic dada for building energy efficiency design.Shading coefficient is an important parameter for shading performance evaluation. The research which is from the perspective of energy efficient, based on heat transfer theory, with shading coefficient as the main evaluation parameter, studies the structure characteristic of the building external shading facilities, energy saving effect calculation and the shading evaluation method. Main research work are: proposed the heat gain calculation model based on direct and diffused radiation transmittance calculation for horizontal, vertical visor and fixed, activities louver shading devices, analyzed the annual energy saving features of the horizontal and vertical shading visor, investigated the slat angle optimization setting and angle adjustment strategy; measured the louver shading energy saving performance and compared with theoretical calculated results. The main conclusions are as follows:(1) Deprives the shading coefficient calculation formulas for horizontal, vertical visor and fixed, activities louver shading in Shenzhen, Analyses indicates that the annual change properties of SC and the direct radiation shielding effect are quiet different, SC can better reflect the energy saving effect of shading structures.(2) Shading facilities should be designed to achieve a reasonable balance among reducing the load, natural light and reduce glare. For the louver shade whose slat width and spacing ratio is nearly equal to 1, the slat angle of the horizontal louver shade should set to 60°, 60°, 90°, 120°for east, west, south and north orientations; the slat angle of the vertical louver shade should set to 45°, 135°, 45°, 90°. (3) Proposes the slat angle adjustment strategy in Shenzhen in summer and winter for the louver shade whose width spacing ratio is nearly equal to 1, the slat angle adjustment range of the louver shade in east and west should set in the range of 45°and 120°, and should set in the range of 60°and 120°. In north orientation activities louver shade don't need to be used.(4) Field tests shows that the external louver shade can reduce the solar heat gain of 40%～70%. The solar heat gain by simulation and testing is relevant, the single day shading coefficients by simulation and testing have some deviation. The error causes by the cooling fan coil unit is the maximum. Reducing the flow rate of fan coil cooling water and raising the indoor temperature control accuracy can great improving the accuracy of the device.