Study On Performance Optimization Of Residential Building Facades In Sichuan-Tibet Region

The development of the local economy in the western Sichuan plateau has been constrained by the poor thermal environment and high energy consumption of buildings.In order to determine a more suitable energy-saving fa?ade form for residential buildings in the western Sichuan Tibetan region and to make full use of the abundant solar energy resources in the region,this paper takes Kangding,a typical city in the western Sichuan Tibetan region,as the research site and uses a combination of field research,theoretical analysis and numerical simulation to study the optimization of fa?ade performance of residential buildings in the western Sichuan Tibetan region.Firstly,this paper investigates the indoor and outdoor thermal environment,the thermal condition of exterior walls and the energy consumption level of building heating in the existing residential buildings in Kangding area.It is measured that the solar radiation intensity on the horizontal surface of Kangding area in winter can reach786W/m2,the indoor air temperature of southwest-facing rooms can reach 15℃ during the daytime under non-heating conditions,and the temperature of southwest exterior wall surface can reach 31℃ at the highest,so the potential of building utilization of solar energy resources is large,but due to the influence of outdoor low temperature environment,the heating energy consumption of existing residential buildings in winter is high and the energy consumption is concentrated in the evening time.According to the problems reflected by the research,this paper proposes the use of solar collector construction in the energy-saving renovation of residential building facades in Tibetan areas of western Sichuan,and takes the south-facing facade as an example,writes a UDF program with dynamic boundary parameters,and uses Fluent software to simulate and compare the thermal performance differences of different construction facades.The results show that the average temperature of the inner and outer surface of the collector facade is significantly higher than that of the traditional insulated facade,and the temperature of the inner surface can be higher than 18℃ throughout the day,and its thermal performance has obvious advantages.Secondly,this paper optimizes the design parameters for the heat-collecting facade.The study shows that,influenced by the outdoor environment and long-wave radiation,the heat-absorbing coating of the heat-collecting wall has a significant impact on the heatcollecting and thermal insulation performance of the wall,and the heat-absorbing coating with high absorption rate and low emissivity should be selected as much as possible;the optimal thickness of the air interlayer is 20～30mm,and if the thickness is too large,the natural convection of the air within the interlayer by the thermal buoyancy force is enhanced;the double-layer insulating glass,due to its low heat transfer coefficient and high Because of its low heat transfer coefficient and high solar radiation transmittance,it is suitable to be used as the glass cover of heat collecting external wall;the structural wall of heat collecting wall should have large specific heat capacity and thermal conductivity,200 mm solid concrete wall and 240 mm clay brick wall have better thermal performance when used as structural wall,and structural wall with good thermal insulation such as aerated concrete is not suitable to be used as heat collecting wall.Finally,based on the Design Builder platform,the winter heating energy consumption of a residential building in Kangding City is analyzed,and the simulation results show that the room heating energy consumption is reduced by 47.8% after the south-facing exterior wall of the existing building is transformed into the heat-collecting wall structure;the accumulated heat consumption of the room with the south-facing window-to-wall ratio of 0.3 is the smallest;the suitable thickness of the heat-collecting exterior wall structure for solid concrete and clay brick should be around 150～300mm.Under this construction,the predicted energy saving rate of the envelope of new buildings with the application of heat-collecting facades in four orientations,namely,east,south,west and north,is 25.3%,52.8%,30.5% and 6.9%,respectively.In addition,it is simulated that the heat-collecting facade construction does not cause indoor "overheating" in summer when applied to the facades of buildings in the western Sichuan region,which is suitable for application in the optimization of energy-saving envelope of residential buildings in the western Sichuan Tibetan region.The research results of this paper are intended to provide theoretical and technical support for the use of passive solar technology to improve the thermal performance of building facades in the energy-saving renovation of residential buildings in western Sichuan Tibetan areas.