The heat transfer across a photovoltaic wall (PV wall) is investigated to determine the cooling load component contributed by building-integrated PV walls. A new definition of equivalent hourly average outdoor temperature is given for simplifying the calculation procedures of the cooling load component. Calculation results show that the cooling load component can be obtained conveniently by using the average outdoor temperature and recommended film coefficients of the special building claddings. The meteorological data of three cities (Hong Kong, Shanghai and Beijing) were used as examples to calculate the heat gains and the cooling load components of typical building walls. Comparing with the results between PV walls and massive walls, the photovoltaic integration in building walls reduces the corresponding cooling load components by 33%-50%. (C) 2000 Elsevier Science S.A. All rights reserved.