Naturally ventilated folded double-skin fa?ade (DSF) for PV integration - Geometry evaluation via thermal performance investigation

Studying the thermal performance of Double Skin Facades (DSFs) with vertical layers has dominated the literature, however, there is still a lack of in-depth research on the performance of DSFs with atypical geometries such as folded cases which can be applied to Building Integrated Photovoltaic (BIPV) systems to improve their performance. To this end, the study evaluates the influence of the fold geometry on heat transfer, flow structure, and airflow rate in the Folded DSF cavities under a hot climate in Iran using an efficient method titled "patching"; the method integrates Soltrace3 with a 2D steady-state CFD model by ANSYS-Fluent. The results show that the fold position and its depth can alter the DSFs performance significantly; the higher the fold depth the more distortion of the flow field inside the cavity; from a practical perspective, the fold position in the upper part of the cavity is suitable for BIPVs application since it can capture 250% higher amount of solar radiation compared to a conventional vertical-layer DSF as the Base Case; the net heat gain through outer layer could improve with increase of fold depth and reach at least 33% higher than the Base Case, meanwhile, the total electricity generation potential of folded cases could be up to 169% higher than the Base Case; thus, the study proved that if the architectural design is of interest, it is highly recommended to consider folded DSFs as a design option.