Comparative Study on Hygrothermal Behavior of Sustainable Building Materials

Abstract

Hygrothermal transfers have a decisive influence on the thermo-hydraulic behavior and durability of building materials. They directly influence energy performance of buildings, thermal comfort of occupants, and longevity of structures. This study presents a comparative analysis of heat and mass transfer mechanisms in various commonly used building materials, such as concrete, cement blocks, compressed earth bricks (CEB), and cut laterite blocks (CLB). The analysis is based on the thermo-hydraulic properties of these materials, as well as on the coupled phenomena of thermal conduction and water vapor diffusion. The materials are assumed to be placed in air. We used a numerical method to solve the equations. This numerical method involved formulating the transport equations according to the Luikov model. These equations are solved using an implicit finite-difference scheme. A Fortran code combined with the Thomas algorithm for solving the equations was developed and validated using the literature. The results are presented as the spatiotemporal evolution of temperature and moisture content at the center of the materials. The results show that hygrothermal transfers depend on the temperature of the air in contact with the materials. When this air temperature increases, the temperature within the materials increases by 5%. However, this increase is more rapid in cementitious materials, where it can reach 10%. The moisture content decreases by 0.3% for most materials, except for cementitious materials, which decrease by 0.5%. Materials with low thermal conductivity conduct less heat and retain more moisture.