Future climate impacts on urban office Buildings: Energy, comfort, and passive solutions in Osaka, Japan

Climate change is a major driver of rising energy demand, with region-specific manifestations that significantly affect environmental conditions, development potential, and human well-being. This study explores the thermal performance and energy demands of a six-story office building in Osaka, Japan, under current (2020s) and projected (2090s) climate conditions. Although extensive studies have explored building energy performance and climate resilience, limited research has focused specifically on hot and humid climates, where extreme temperature and moisture levels significantly impact building behavior. EnergyPlus is used to simulate indoor air temperature, operative temperature, Predicted Mean Vote (PMV) for thermal comfort, and the energy consumption of a Variable Refrigerant Flow (VRF) heat pump system. Results indicate significant overheating in unconditioned zones, with operative temperatures exceeding 36 °C during summer in the 2090s. Conditioned zones also experience challenges, with cooling set-points surpassed on extremely hot days. Energy consumption analysis reveals a 20 % increase in cooling demand, from 3323 kW in the 2020s to 3983 kW in the 2090s, highlighting the impact of climate change. The findings emphasize that passive cooling strategies, such as cross-ventilation, dynamic shading, and high-performance insulation, can reduce cooling loads by 15-25 %. These results underscore the urgent need for climate-resilient building design and provide actionable insights for adaptive strategies in hot-humid urban environments. Future work will integrate adaptive comfort models and explore hybrid passive-active systems to enhance resilience. Future research will integrate adaptive comfort models and investigate hybrid passive-active systems to further enhance building resilience under extreme climate conditions.