This study evaluates the potential of rubberized gypsum composites as sustainable wall materials for improving energy efficiency in buildings located in arid climates, using M'sila, Algeria, as a representative case. The novelty of the work lies in the dual experimental and simulation-based analysis of recycled rubber waste (RW) incorporation, specifically addressing thermal comfort under arid climatic conditions. Natural sand was partially replaced with recycled RW at levels of 0%-50% by volume. Laboratory experiments quantified the effects of RW on the mechanical strength, density, and thermal properties, while simulations assessed the thermal insulation of walls under arid conditions. Key parameters included wall configuration (single/double layer), thickness, air cavity integration, and surface coatings. The results showed that increasing RW content reduced mechanical strength and density but significantly improved, the thermal insulation performance of the composite with thermal conductivity decreasing by 52% at 50% RW. Simulations revealed that thicker walls with integrated air cavities and coated surfaces enhanced thermal inertia, increasing time lag (phi) and reducing decrement factor (& fnof;). These design strategies stabilize indoor temperatures and mitigate peak heat fluxes, thereby reducing energy demand. By valorizing nonbiodegradable waste, the proposed composites lower costs, reduce embodied energy, address RW disposal challenges, and offer practical solutions for climate-responsive, sustainable buildings in arid regions.