Experimental and numerical approaches for building thermal load analysis for PV-integrated buildings
Due to climate change, population growth, carbon emissions, and many other reasons, solutions must be found for a sustainable future. The building sector is the world's largest energy consumer; buildings consume 41% of the total energy produced in the U.S. Rooftop-mounted BIPVs are emerging and becoming more affordable with the recent advancements in photovoltaic cells. In this study, the indirect benefit, reduction of thermal gain through the roof, is studied using experimental research and EnergyPlus building energy simulations. By interpreting changes in roof surface temperature and sensible cooling load in a university building in U.S. climate zone 4A. PV surface albedo, thermal resistance due to additional material, shading effect, and convective cooling effect in the air gap reduces the thermal gains through the roof. However, due to the lack of a CFD module to solve thermal flow and airflow in the air gap and PV panels are only recognized as shading elements in EnergyPlus. In the initial stage of the study, surface temperature gaps were observed in measured experimental and simulated data. A linear regression analysis was conducted between local outdoor air and surface temperature to improve the surface temperature gap and refine sensible cooling load reductions. As a result, the average absolute shading surface temperature gap between measured data and simulated data was reduced to 9.7% from the initial 11.1%. The 2.94% initial reduction of the sensible cooling load compared to a building with a conventional roof-top was more than doubled due to surface temperature improvement, which reduced the total sensible cooling load by 8% during the summer. Suggest that even the slightest temperature reduction leads to less heat gain through the roof and a reduction of building cooling load.