Thermal mass and cooling demand in a hot-dry commercial building: a controlled 2×2 EnergyPlus case study

climates, yet its quantified impact on cooling demand in real commercial buildings is often reported through loosely controlled or methodologically inconsistent comparisons. This study presents a structured building-scale case study that isolates the effects of architectural form and material choice on cooling-dominated electricity use using a controlled 2×2 matrix. A historic caravanserai in Khorramabad, Iran, is examined under four configurations: traditional form–traditional materials (TT), traditional form–modern materials (TM), modern form–traditional materials (MT), and modern form–modern materials (MM). All scenarios share identical geometry, thermal zoning, schedules, internal gains, and climatic boundary conditions, and are simulated using EnergyPlus under an electricity-only operational assumption. Annual electricity consumption is reported both as absolute values and area-normalised intensities to ensure direct comparability across configurations. Operational CO 2 emissions are derived transparently from electricity use using a fixed grid emission factor, while envelope-level embodied CO 2 is assessed separately to maintain clarity between operational and material impacts. The results show that configurations with higher effective thermal mass consistently reduce cooling-driven electricity demand relative to the modern lightweight baseline, with the largest reductions observed when mass-masonry assemblies are combined with compact, covered spatial morphologies. A targeted one-factor sensitivity analysis further confirms thermal mass and infiltration as the dominant drivers of performance differences. By re-examining a classical thermal engineering problem through a tightly controlled, reproducible case-study framework, the findings provide transferable insight for cooling-dominated commercial buildings in hot-dry regions.