The integrated photovoltaic system building design (BIPV) is becoming popular among architects and design engineers. This paper reports on an empirical approach for BIPV applications in building design. A brief description of the theory and mechanism is given followed by experimental and numerical validation. The procedures and estimation methodology conducted in previous research is documented. The investigation procedures and devices employed are described and the experimental results are illustrated. Statistical analysis and regression functions are employed to simplify the solar irradiation estimation procedure. The framework for evaluating building solar irradiation applications is described in detail. Conclusions are drawn regarding the BIPV evaluation operational characteristics for building solar energy applications as a simplified approach for architects and design engineers. The results with local parameters can be used to estimate the tilted planes for BIPV application. (c) 2004 Elsevier Ltd. All rights reserved.