Streamlined CFD simulation framework to generate wind-pressure coefficients on building facades for airflow network simulations

Abstract

Building energy modeling software generally comes with capable airflow network solvers for natural ventilation evaluation in multi-zone building energy models. These approaches rely on arrays of pressure coefficients representing different wind directions derived from simple box-shaped buildings without contextual obstructions. For urban or obstructed sites, or more complex building shapes, however, further evaluation is needed to avoid geometric oversimplification. In this study, we present an automated and easy-to-use simulation workflow for OpenFOAM-based exterior airflow simulations to generate arrays of pressure coefficients for arbitrary building shapes and contextual situations. The workflow is compared to other methods commonly used to obtain pressure coefficients for natural ventilation analysis. Finally, we assess for which climate zones and building types modelers should rely on more accurate CFD-based pressure coefficients and where it may be justifiable to rely on easier and readily available analytical approaches to determine pressure coefficients. Results suggest that existing workflows lead to significant error in predicted comfort hours for climates in the Global South and modelers should consider CFD-based facade pressure coeficients.