Study On Shading And Daylighting Regulation Of Double Skin Facade

Double skin facade are widely used in contemporary office buildings because of their lightness,beauty,transparency and lighting characteristics,resulting in high solar heat gain and glare problems,which can seriously affect the energy consumption and indoor comfort of the entire building.The use of shading devices in buildings can reduce building energy consumption and also provide a better indoor environment for building occupants.The different shading and lighting regulation of the ventilated double skin facade with blinds has an important impact on its thermal performance,natural lighting performance,indoor lighting,permeability and glare.Therefore,this paper conducts in-depth research on the shading and visual comfort of ventilated double skin facade with blinds,and explores the shading and lighting control strategy and visual comfort evaluation method of ventilated double skin facade with blinds,so as to provide a theoretical basis for improving the energy efficiency of double skin fa(?)ade building,realizing building energy conservation and improving indoor light environment.First,the optical model of the complex fenestration system is explored.The bidirectional scattering distribution function method is introduced in detail,and the accuracy of the optical model established by the three methods of bidirectional scattering distribution function method,ray tracing method and interface energy balance method is compared and analyzed through experimental test data.Finally,the optical model of ventilated double skin facade with blinds established by bidirectional scattering distribution function method can be obtained that is more accurate than the ray tracing method and the interface energy balance method,and is closer to the experimental results.Secondly,the main influencing factors of visual comfort are explored.The advantages and disadvantages of the main visual comfort evaluation indicators were discussed,among which the useful daylight illuminance and daylight glare probability were more suitable indicators for visual comfort evaluation.Useful daylight illuminance not only provides useful daylight levels,but also provides the frequency of occurrence of excessive daylight levels that can cause discomfort to personnel(i.e.,glare)and unwanted heat gain from the sun.The daylight glare probability has a strong correlation with the user’s response to glare perception.Finally,a closed-loop control strategy for shading blinds is proposed,that is,a joint control method combining indoor and outdoor sensor feedback combined with slat angle+blind height+indoor light brightness adjustment is proposed.The cut-off angle control strategy,three different fixed slat angle(0~o,30~o,60~o)control strategy and the shading blinds control strategy proposed in this paper are compared and analyzed from the four aspects of lighting performance,visual comfort,air conditioning/heating and artificial lighting energy consumption.In addition,the correlation between E_V illuminance value and ceiling illuminance value was analyzed to convert the applicability of shading device control in reality.The results show that the shading blinds control strategy proposed in this paper can effectively improve the indoor light environment,prevent glare to a large extent,and greatly reduce the energy consumption of artificial lighting.