Abstract
A building envelope is a multi-layer porous structure. It transfers heat and moisture to balance the indoor and outdoor temperature difference and water vapor partial pressure difference. This is a typical coupled heat and moisture migration process. When the space is filled with moist air, water or ice, it will directly affect the thermal properties of the material. With respect to moisture coming through the wall into the indoor building, it will also affect the indoor environment and the energy consumption due to the formation of latent heat. However, the moisture transfer process in the building envelopes is not taken into account in the current conventional thermal calculation and energy consumption analysis. This paper analyzes the indoor thermal and humidity environment and building energy consumption of typical cities in Harbin, Shenyang, Beijing, Shanghai, and Guangzhou. The results show that it is obvious that the coupled heat and moisture transfer in the building envelopes has an impact on the annual cooling and heating energy consumption, the total energy consumption, and the indoor thermal and humidity environment. The geographical location of buildings ranging from north to south influences the effect of coupled heat and moisture transfer on the annual energy consumption of the building, moving from positive to negative. It is suggested that the additional coefficient of the coupled thermal and moisture method can effectively correct the existing energy consumption calculation results, which do not take the consumption from the coupled heat and moisture in the building envelopes into account.
Highlights
Most of the materials of a building’s wall are porous media [1,2,3]
The traditional analysis of a building’s energy consumption and indoor thermal and humidity environment pays a great deal of attention to the heat transfer through the wall [4,5,6], but the effects of coupled heat and moisture transfer on the indoor environment and energy consumption of related buildings are often neglected [7]
We strived to use the envelope heat and moisture transfer more rationally in the building in order to achieve the purpose of reducing building energy consumption and improving indoor comfort
Summary
Most of the materials of a building’s wall are porous media [1,2,3]. When exposed to an outdoor dynamic thermal and humidity environment with large temperature variations, wind, and precipitation, the building wall material will undergo a heat and moisture exchange with the indoor environment due to the difference of temperature and water vapor pressure. The heat and mass transfer through the building envelope directly affects the main parameters of indoor thermal comfort, such as air temperature, air relative humidity, radiant temperature, etc. Thereby, it affects the thermal sensation for the occupants of the area of energy balance, such as their skin moisture and tactile sensation [8,14,15]. It can be seen that the heat and moisture transfer process have an extremely important influence on the thermal performance of building envelopes, building energy consumption and the indoor environment.
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