Hygrothermal performance of diatomite PCM composite walls for energy-efficient construction in hot-arid climates

In response to the growing demand for energy-efficient construction materials tailored to hot-arid climates, this study proposed and rigorously evaluated an innovative composite wall system that synergistically combined diatomite with paraffin. Eight wall assemblies were subjected to detailed numerical simulations, including five hollow brick walls with varied internal and external finishing layers and three concrete walls differentiated by aggregate composition. To ensure contextual relevance, the study incorporated real meteorological data from three representative desert locations: Ghardaïa (Algeria), Djerba Mellita (Tunisia), and Abu Dhabi (United Arab Emirates). In parallel, a dual-compartment experimental apparatus was developed to investigate the coupled thermal and hygric behavior of mortar and concrete composites under controlled environmental conditions. These experimental measurements provided critical physical insights and served to validate the finite element model, achieving deviations below 5% and thereby confirming the robustness of the numerical framework. The results demonstrated that the use of diatomite either alone or in combination with paraffins whether as finishing layers or as a partial replacement for sand and gravel in mortar and concrete mixtures significantly improved hygrothermal regulation. These systems effectively reduced internal heat flow and maintained temperature and humidity within comfort thresholds. Among all configurations, the brick wall with both internal and external finishes made from diatomite and 12% paraffin was identified as the most innovative and high-performing configuration, achieving up to a 40% reduction in heat flux while ensuring superior thermal insulation and humidity stability.