Discrete-Continuous Approach to the Moisture Transfer in Building Enclosures

In the field of the moisture regime of the enclosing structure, there are methods for assessing the stationary moisture state that have a rather low calculation accuracy, as well as methods for assessing the unsteady-state moisture regime which cannot be implemented without using numerical methods and a computer. Based on the introduced scale of the moisture potential F, a new mathematical model of heat-moisture transfer has been developed. The equation of moisture transfer has been derived on the basis of the theory of potential importance. The boundary conditions of moisture exchange of the third kind have been described. A method for calculating enclosing structure moisture regime using a discrete-continuous approach is proposed, and the final formula that allows one to determine the distribution of the moisture potential has been derived. The distribution of moisture over the thickness of the enclosing structure is calculated for a single-layer wall structure made of aerated concrete and a multilayer wall with a clay brick base and silicate brick cladding. Mathematical modeling of the walls moisture state was made according to three separate methods based on the theory of moisture potential. It is shown that the current engineering method for assessing moisture regime gives an error of 21.13% compared to the numerical method that has an error of only 2.39%. Thus, it was concluded that the proposed method using the discrete-continuous approach could be implemented into the construction industry. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.