This study investigates the integration of a bio-sourced building material-specifically, conventional clay enhanced with 10% eggshell powder-into the envelope of a typical two-level building in Morocco. The thermophysical characterization of this composite (thermal conductivity, specific heat capacity, and density) was implemented into EnergyPlus to evaluate its application at the whole-building scale through dynamic thermal simulations. The research quantifies the composite's impact on indoor temperatures, energy consumption, and thermal comfort across three representative Mo-roccan climates: Casablanca (Nouacer), Tangier, and Nador. The simulation results demonstrate that integrating the 10% eggshell composite into the building envelope reduces heating and cooling energy demands by up to 40% compared to conventional clay. Furthermore, the material significantly improves indoor thermal comfort by re-ducing total annual discomfort hours outside the thermal comfort setpoint range (20.00-24.00 °C) by up to 40%, offering a viable pathway for greening the building stock through agricultural waste valorization.