Research On Hygrothermal Performance Of Multilayer Wall Under The Solar Radiation

Building energy consumption is necessary to satisfy the building's function and comfortable services what is accounted for 19%～20% in all consumption in China,but still lower than the average level of 30%～40% in developed countries.So the relative value of building energy consumption to total energy consumption and the absolute value of building energy consumption are facing growing pressure.In hot summer region,the indoor air temperature,the load of HVAC system and energy consumption is increased by the solar radiation transfer through the building's envelope.In cold winter area,the solar radiation transferred into the room can also increase the indoor air temperature and decrease the energy consumption.It is clear that solar radiation has important effect on building energy consumption in different region of China.In this paper, using Fourier's law and Fick's law for the basis,and then taking air humidity ratio and temperature as the driving potentials,a dynamic model is established for evaluating the transient heat and moisture transfer behavior in building multilayer wall according the mass and energy conservation law which also considered the impact of solar radiation.Four types of multi-layer wall which main material are cement mortar-brick-cement plaster, cement mortar-lightweight concrete-cement plaster, cement mortar-concrete-gypsum board and cement mortar-brick-gypsum board were taken into computational simulation.The hygrothermal performance of multi-layer wall was analysed under the effect of solar radiation.The computational simulation results indicated that the solar radiation had important effect on the hygothermal performance of multi-layer wall.The temperature of exterior wall is highly increased unnder continuous irradiation which raises the heat transferred from outdoor to indoor air.The solar radiation has little effect on the interior wall temperature which mainly affect by the indoor air temperature.The exterior wall's saturation vapor pressure will increase because of the temperature raise under the solar radiation,then the absolute of this interface will also increase. The continuous high humidity and temperature climate will cause high humidity accumulation inside the wall which have large harm to the multi-layer wall's durability.The computational simulation of four different cities in four different regions provides detailed data to analyze the hygrothermal performance of multi-layer wall precisely under the effect of solar radiation.