Applicability of Vapor Transport Theory for Common Wall Types in Mixed Climate Zone of China

Abstract

To decrease building energy consumption and improve indoor thermal environment, mixed climate zone (MCZ) imitates northern buildings to use immature thermal insulation technology to new or retrofitting buildings; however, it leads to condensation inside or on the surface of building enclosure (BE), which makes building energy consumption increasing, improves fungus growth, deteriorates indoor air quality (IAQ), and lowers durability. Generally, dew-point method and vapor transport theory is used to determine condensation; however, the former method is only used to the surface of BE without considering the influence of heat and air on moisture transfer, and the latter method could be used to the inside of BE without considering the influence of liquid water transfer and vapor transfer on temperature; furthermore, hygrothermal characterization of building materials is usually considered as constant, and in fact, it is variable. Meanwhile, due to capillary condensation existing in porous materials, even though relative humidity (RH) (water vapor pressure ratio) is less than 100 %, condensation also could occur. So the applicability of vapor transport theory is discussed in several common wall types including 240 mm brick wall, 180 mm concrete wall, and 190 mm AAC wall in MCZ in China.