Optimization of building envelopes for zero-energy social housing in southern brazilian bioclimatic zones using multi-criteria decision analysis

This study explores the optimization of building envelopes to achieve Zero Energy Building (ZEB) performance in social housing located in humid subtropical climates. Using the BEopt simulation tool, multiple envelope configurations were generated and assessed based on energy demand, thermal comfort, and initial cost. The ELECTRE III multi-criteria decision method was applied to rank optimal solutions for three Brazilian bioclimatic zones. Results show that optimized envelopes can reduce air-conditioning energy consumption by up to 30%, increase comfort hours by 35%, and decrease the number of photovoltaic modules required to reach energy balance by one-third. The best-performing solutions combined moderate wall insulation, light-colored roofs and façades, controlled window-to-wall ratios, and predominantly south-facing orientations. These findings highlight the importance of coupling optimization algorithms with decision-support models to identify cost-effective and climate-responsive design strategies. The proposed approach provides a replicable framework for advancing energy-efficient and affordable housing in developing countries. The results are primarily applicable to humid subtropical (Cfa) climates, based on case studies located in three Brazilian bioclimatic zones within the state of Rio Grande do Sul.