Development of a holistic evaluation system for BIPV façades

Façades with building-integrated photovoltaics (BIPV) have the advantage that they can produce renewable electric energy. Compared with conventional façades, BIPV façades have therefore a valuable additional property that can generally contribute to increasing the degree of sustainability of buildings. A holistic assessment system for BIPV façade systems for office and administration buildings was developed in the framework of the project "MULTIELEMENT II" at the Fraunhofer Institute for Wind Energy and Energy System Technology (IWES) in Kassel, Germany. The aim of this research was a comparison of conventional façade systems with BIPV façade systems regarding different technical, economical, sustainability, and design criteria. This paper discusses the basic conditions for a holistic evaluation of BIPV façades in comparison with conventional façades. A method for the execution of a holistic evaluation and characteristic values for a comparison interpretation of results is presented. Façade systems are evaluated regarding both quantifiable and non-quantifiable properties by means of a Microsoft Excel-based evaluation tool. The tool facilitates the comparison and evaluation of planned or built façades with and without BIPV. The detailed evaluation results aim to facilitate the certification of BIPV façade systems in the framework of sustainable building certification systems such as the German DGNB.