Research on the calculation method of key thermal parameters and the thermal performance differences in different climate zones of the facade BIPV component

Evaluating the thermal performance of facade BIPV components in practical engineering applications remains a challenge. To quantify the impact of their thermal effects, this study proposes the equivalent additional thermal resistance (ΔRBIPV) and the equivalent heat transfer coefficient (KBIPV), together with their calculation methods. The differences in ΔRBIPV among five climate zones in China, including the severe cold zone, cold zone, hot summer and cold winter zone, hot summer and warm winter zone, and mild climate zone, are systematically analyzed. The KBIPV values for the five climate zones are further compared with the corresponding limits of external wall heat transfer coefficients (Klimit) specified in the building thermal code, and based on this comparison, strategies for reducing external wall insulation thickness are proposed. The results indicate that the annual average ΔRBIPV values for the five climate zones are 1.07, 1.01, 0.98, 0.97, and 1.03 m2 K/W, respectively. With the application of facade BIPV components, the insulation thickness of external walls in Zone I and II can be reduced by 42 mm and 39 mm, respectively, while no additional insulation layer is required for Zone III, IV, and V.