Application analysis of theoretical moisture penetration depths of conventional building material

Abstract

Due to the significant impact of indoor humidity on indoor air quality, human comfort, and energy consumption, many researchers have investigated the use of various hygroscopic materials to moderate indoor humidity levels and save energy. The results show that the indoor relative humidity of the room with hygroscopic materials is more stable and moderate. Hygroscopic materials can be also used to reduce the energy consumption of heating, ventilation, and air-conditioning system. Although many laboratory measurements and numerical simulation studies have been done for hygroscopic materials, there is little study on moisture penetration in materials with limited thickness in practical engineering application. Moisture penetration depth has great influence on material moisture parameters and indoor humidity simulation model, such as effective moisture penetration depth model. In this article, a theoretical moisture penetration depth model is developed, and the theoretical moisture penetration depths of conventional building materials are calculated. The results show that when the wall material thickness is below the 1/e theoretical moisture penetration depth, the proportional relationship between the moisture buffer value and the square root of time is not kept. When the wall material thickness is thinner than its theoretical moisture penetration depth, ignoring the material thickness might cause significant error in indoor moisture content calculation using effective moisture penetration depth model.

Determination of optimal plaster thickness for moisture buffering of indoor air

“…The theoretical moisture penetration depth of a sample can be calculated using Kirchhoff potentials that describe moisture transport (Rode et al, 2005). The NORD test methodology (Rode et al, 2005) and Wan et al, (2017) propose a simplified method for an approximation based on a sinusoidal variation of the surface moisture content, u, over an amplitude of Δu s . Assuming that an exponential decrease in amplitude from the surface to a depth dp, Δu dp is given by Equation 1.…”

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