Iranian Sustainable Building Scientific Association International Journal of Urban Management and Energy Sustainability 2538-1628 6 4 2025 10 01 Optimizing Thermal Performance of Double-Wall Systems in Tehran's Climatic Conditions: A Simulation-Based Approach 260 277 731560 10.22034/ijumes.2025.2057838.1307 EN Ashkan Hassani Department of Architecture, CT.C., Islamic Azad University, Tehran, Iran 0009-0008-1213-5099 Shooka Khoshbakht Bahramani Department of Architecture, CT.C., Islamic Azad University, Tehran, Iran 0000-0002-6987-9987 Vahid Ghobadian Department of Architecture, CT.C., Islamic Azad University, Tehran, Iran 0000-0002-5040-0382 Journal Article 2025 04 13 Energy efficiency is an essential part of sustainable urban development strategies, especially in cities with wide temperature ranges like Tehran, where a significant amount of energy is consumed to maintain occupants’ comfort. Double-wall systems with an air cavity can minimize reliance on mechanical heating and cooling sources; however, there are few quantitative studies of insulation materials in Tehran’s climatic conditions. In this study, we use a simulation-based approach utilizing the DesignBuilder program and EnergyPlus engine to evaluate the thermal performance of eight insulation materials (polystyrene, PVC, rock wool, fiberglass, polyurethane, glass wool, polyurethane foam, and extruded polystyrene) in double wall systems, with insulation thickness ranging from 5 to 15 cm, for a typical residential unit located in Tehran, using the actual climate data to analyze heat transfer .The results showed that both the insulation type and thickness play an important role in energy efficiency. Polyurethane and polyurethane foam delivered the best performance in this study with approximately a 30% reduction in heat transfer at 12 cm thickness. Other materials also exhibited more energy efficiency than a non-insulation process, although performance improvement was limited as thickness increased. The study concludes that high-performance insulation, particularly polyurethane at 12 cm, can effectively enhance thermal efficiency in Tehran’s residential buildings. This research provides a technical basis for optimizing wall systems in urban environments. Future studies should incorporate cost, environmental impacts, and advanced insulation technologies to develop more comprehensive strategies for sustainable building design in Tehran and comparable climates. https://www.ijumes.com/article_731560_91528dee6c4a69e66ef08af15a8a6c24.pdf