Humanity has used raw earth in construction for millennia due to its hygrothermal properties, providing comfort for building insulation. However, raw earth is sensitive to moisture problems. Therefore, the construction and design of earthen buildings involve controlling this ancient material's heat and mass transfer. This study was carried out to numerically model simultaneous heat and mass transfer through certain forms of building envelopes constructed with compressed earth blocks. In this context, we have presented a mathematical model governing hygrothermal phenomena, based on the results of recent studies. A numerical approach employing the finite element method was used to carry out this project, the model was developed using COMSOL Multiphysics software. The aim of this research is: firstly, to anticipate the wall's ability to moderate environmental hygrothermal variations during real-life scenarios; secondly, to describe the saturation phase of a wall immersed in water, and the effect of this situation on hydrothermal parameters. The simulation results obtained from the numerical model agree with experimental measurements of relative humidity, water content, and temperature. Indeed, to have a simulation package specifically dedicated to predicting temperature profiles, water content, and relative humidity inside a building envelope, we need to take greater account of the dynamics of mass transfer phenomena and the choice of earth material in walls.