Multi-objective performance assessment of rear-ventilated BIPV double facade using CFD

Rear-ventilated BIPV facades enhance both building thermal performance and PV efficiency. This study numerically investigates the cooling performance of such facades under varying cavity geometries using a single-room CFD model with a non-gray, two-band discrete ordinates (DO) radiation approach. Results show that increasing cavity depth and vent height strengthens airflow and convective heat transfer. The optimal configuration enhanced wall heat removal by approximately 37% compared to the worst-performing case. While ventilation significantly reduced PV temperatures, differences among configurations were minor due to the aluminum back sheet's high thermal conductivity, which promotes heat spreading. Notably, airflow organizations were found to govern the spatial heat flux distribution. These findings highlight the critical role of geometric design and cavity airflow organization in the development of high-performance, energy-efficient BIPV envelope systems.