Techno-economic optimization of an NZEB using PMV-controlled HVAC: Case studies from Iran

To overcome reliance of fossil fuels and to improve environmental sustainability in the building sector, this study focuses on the design and multi-objective optimization of a Nearly zero energy building (NZEB) for four distinct climatic regions in Iran—Tehran, Tabriz, Yazd, and Bandar Abbas. The case study building was a villa consisting of six thermally conditioned spaces (four bedrooms, a living room, and a kitchen). The optimization objectives were to minimize thermal discomfort hours, reduce annual net energy demand, and lower the embodied energy of photovoltaic (PV) panels while maintaining compliance with the low-energy building classification with respect to the fundamental design parameters of NZEBs. Due to variety of design parameters, a Bayesian optimization algorithm was employed due to its robustness in handling noisy, computationally expensive simulations. The results demonstrated that all optimized models satisfied the European NZEB criterion, with annual net energy demands well below 50 kWh (Tehran: 5.73 kWh, Tabriz: 25.83 kWh, Yazd: 3.74 kWh, Bandar Abbas: 2.17 kWh). The number of PV panels required ranged from 15 in Tehran to 27 in Tabriz, with polycrystalline panels consistently preferred for their lower embodied energy. The PMV setpoints reflected the influence of the building’s thermal inertia, deviating from standard comfort limits (Heating PMV = −0.5, Cooling PMV = 0.5). Thermal dissatisfaction remained below 14% in all cases, confirming satisfactory comfort levels. Moreover, the annual energy demand per conditioned area was maintained below 100 kWh/m² across all cities. The results highlight the effectiveness of the proposed optimization framework for achieving sustainable and energy-efficient building design in diverse climatic conditions.