Abstract
12 Improving energy efficiency and power supply reliability in standalone buildings is 13 essential for sustainable development. Enhancing building envelopes with phase change 14 materials (PCM) can address economic challenges and reduce peak power demand 15 issues for Heating, Ventilation, and Air Conditioning (HVAC) systems. This study 16 proposes an optimized approach to determine the ideal location and thickness of PCMs 17 across the roof while analyzing the impact of rooftop PV on the thermal performance of 18 PCM-enhanced roofs for a building designed in accordance with ANSI/ASHRAE 19 Standard 140-2001. Furthermore, effective Building Evaluation Model (BEM) strategies 20 are incorporated into a techno-economic assessment to optimize a PV, fuel generator, 21 and battery energy system, with the goal of minimizing the cost of energy (COE). 22 Utilizing a BioPCM with a melting point near the building's comfort zone (25°C), the 23 study finds that a single layer (1.12 cm) of PCM on both sides of the roof insulation 24 delivers the best performance. The proposed method achieves over 4.79% annual energy 25 savings, reduces energy costs to $0.15/kWh, contributes over 50% from renewable 26 resources, and lowers CO₂ emissions by 41–54% compared to the reference case without 27 roof enhancements. Additionally, when PV shading is implemented, heating demand is 28 reduced by 14.3% with standard roof insulation and by 6.9% with poor insulation. 29 Similarly, cooling demand is reduced by 7.2% with standard roof insulation and by 2.3% 30 with poor insulation. These findings provide valuable insights for various stakeholders 31 in designing rooftop PV system strategies that enhance building power supply and 32 support sustainable development goals. 33