BIM-Integrated Optimization of Residential Building Form and Envelope Design for Operational Energy and A1–A3 Embodied Impact in a Hot-Arid Climate

This study asks how early-stage residential building form and envelope decisions affect the trade-off between annual operational energy and A1–A3 embodied impact in a hot-arid Saudi context. The motivation is the need for workflows that evaluate building geometry, window-to-wall ratio (WWR), orientation, and envelope assemblies together, rather than treating operational simulation and embodied-impact assessment as separate post-design procedures. A BIM-integrated parametric framework was developed by linking Rhino–Grasshopper massing, Honeybee–EnergyPlus operational energy simulation, Rhino.Inside.Revit quantity generation, Tally life-cycle assessment, Excel-based post-processing, and Wallacei NSGA-II optimization. The case study generated 5000 residential design alternatives for Riyadh, Saudi Arabia. After applying area and WWR filters to retain architecturally comparable alternatives, 45 solutions remained; Pareto analysis identified eight non-dominated entries that collapsed into two unique representative configurations. The lower-operational configuration reduced annual operational energy from 81,729 to 76,406 kWh/yr, corresponding to 6.5%, while increasing A1–A3 embodied impact from 299,966 to 303,751 kg CO2eq, corresponding to 1.3%. Regression analysis across all 5000 solutions showed that total floor area explained 92.6% of operational energy variation and 98.6% of embodied-impact variation. The findings demonstrate that the proposed framework supports transparent early-stage trade-off interpretation, while the results remain case-specific to the selected variables, assumptions, and LCA database.