BIPV Form Factor as an Approach for the Energy Performance of Buildings Exemplified for the Location of Tabriz (Iran)

Building form and envelope surfaces play a significant role in energy performance assessment and the generated energy potential of the building integrated photovoltaics (BIPV) concept in early-stage design. To increase the energy efficiency level, form factor (FF) is proposed as a helpful tool that provides a strong relationship between the exposed surface areas and the treated floor area (TFA). This research aimed at developing a parametric study to determine the related balance (correlation) between the TFA and needed BIPV area in the form enclosure to meet specific primary energy demand (SPED) according to the passive house standard (PHS). For this purpose, various form types including square, rectangle, L, and T shapes-which is derived of four modular cubes- classified based on the same form factor (FF). Optimal form selection per group carried out through the BIPV potential evaluation for the exposed surfaces in six azimuths separately. Afterward, BIPV efficiency level examined by its utilization factor and coverage index scenarios based on façade and roof combination priorities. The results indicate that the generated energy sufficiency is affected by the form configuration and its orientation. Additionally, the optimal BIPV-based FF value of 0.71 implies the priority of roof-based scenarios for less BIPV utilization. Finally, the correlation value for the BIPV coverage index relative to the total envelope for the optimal forms and orientation is higher than 0.92, which can be extended to other forms in different locations as an assessment model.