Effect Of Exterior Wall Decoration Layer On Building Energy Consumption In Severe Cold Area

In northern China,the energy consumption of heating in winter is huge,and the thermal performance of exterior wall veneer has been neglected for a long time.In fact,due to the role of solar radiation and long-wave radiation heat transfer,its radiation characteristics significantly affect the energy-saving performance of building exterior walls.In addition,the air layer and metal parts also have an impact on building energy consumption..In this paper,two main radiation heat transfer parameters,solar radiation absorption coefficient and emissivity,as well as the thickness of air layer and the size of plate,are selected to study the influence of radiation parameters and structural changes on building heating energy consumption by numerical simulation.The influence of variables on heat transfer of single wall is simulated by CFD simulation software Flovent,and the influence of variables on energy consumption of whole building is simulated by energy consumption simulation software Energyplus.In addition,because Energyplus can't set up a specific structure,the equivalent thermal resistance of the air layer will be calculated when Flovent studies the construction variables,which can be used for the subsequent energy consumption simulation.Because the existing specifications only give the radiation parameters of some specific materials,it is impossible for architects to notify the apparent characteristics of materials directly related to the radiation parameters,so this paper first analyses the relationship between the apparent characteristics and radiation parameters of commonly used decorative materials by means of experimental tests,and concludes that the absorption coefficient of solar radiation is mainly related to the color brightness,and is approximately linear.Equation p=-0.01B+1.19.The emissivity is mainly related to the material of the material.The emissivity range of the common materials is obtained.The non-metallic materials are mainly concentrated in the range of 0.7-1 and the metal materials are in the range of 0-0.2.Because the facing layer is closed,the research can not obtain the structure form of the facing layer,so through consulting the literature and the atlas,the structure type and the specific structure data of the facing layer are summarized.Thereafter,through field investigation,the numerical range of radiation parameters and the size range of sheets for various types of buildings in actual design are summarized.In addition,before the simulation,thermal tests were carried out on two walls with different kinds of facing materials of the same base and one wall with dry-hanging structure.The temperature and heat flux intensity of the inner and outer walls were obtained.According to the measured wall model,the measured data and simulation data were compared to verify that the simulation model can be used for facing.Study on the radiation characteristics and tectonic changes of the strata.Finally,the wall heat transfer and building energy consumption under the influence of radiation parameters and structural changes are simulated in order to provide energysaving guidance for building exterior wall decoration design in cold areas.The simulation results show that the radiation parameters are the main factors affecting the energy consumption of the combined veneer.When the emissivity is constant,with the increase of solar radiation absorption coefficient,building heating energy consumption decreases,refrigeration energy consumption increases and total energy consumption decreases.When ?=0.9,the solar radiation absorption coefficient increases by 0.1,heating energy consumption decreases by 0.96% and total energy consumption decreases by 0.25%.When the solar radiation absorption coefficient is constant,with the increase of emissivity,building heating energy consumption increases,refrigeration energy consumption decreases,and total energy consumption increases: when ?=0.3,the emissivity increases by 0.1,heating energy consumption increases by 0.45% and total energy consumption increases by 0.18%.For dry-hanging veneer,the influence of radiation parameters and structural factors should be considered comprehensively.The comprehensive influence of stone veneer can reduce heating energy consumption by 6.8% and total energy consumption by 2.5%,and that of metal veneer can reduce heating energy consumption by 6.9% and total energy consumption by 3.4%.