Jaue2025-022 Thermal Performance Representation of BIPV Double-Skin Facades Using Seasonal Equivalent Thermal Resistance under Dynamic Boundary Conditions

Abstract

The dynamic heat transfer process of building-integrated photovoltaic double-skin facade (BIPV-DSF) systems is complex, and traditional fixed thermal parameters are difficult to accurately characterize their heat transfer characteristics under different operating modes. To parameterize the dynamic heat transfer process of BIPV-DSF systems, this study proposes a seasonal equivalent thermal resistance method based on the relationship between characteristic temperature difference and heat flux through the ventilation-channel-side wall (VCSW). Using measured PV back panel temperature and outdoor air temperature as boundary conditions, steady-state and transient CFD models were established for summer open- VC and the winter closed-VC condition. The relationship between heat flux and characteristic temperature difference was analyzed, and the applicability of the equivalent thermal resistance method under typical-day dynamic boundary conditions was evaluated. The results show that, under summer open-VC conditions, heat flux exhibits a strong linear relationship with the characteristic temperature difference. Under the winter closed-VC condition, a significant correlation is also observed, although the thermal response differs markedly from that in summer, indicating that equivalent thermal resistance parameters should be established separately for different seasons and operating modes. Further validation demonstrates that the proposed method can effectively characterize the cumulative heat transfer over a typical day, while its accuracy in predicting hourly transient heat flux remains limited. The findings provide a reference for the parameterized application of BIPV-DSF systems in building energy analysis.