Paper Conference

Proceedings of SimBuild Conference 2012: 5th conference of IBPSA USA


Using CFD Simulations to Improve the Modeling of Window Discharge Coefficients

Erin L. Hult, Gianluca Iaccarino, Martin Fischer
Lawrence Berkeley National Laboratory, Berkeley, CA
Stanford University, Stanford, CA

Abstract: Accurate parameterization of flow through window openings is necessary in order to model passive and mixed-mode ventilation strategies using airflow network models and energy simulation tools. In these tools, little guidance is typically provided on selecting airflow parameters such as the discharge coefficient for windows. Detailed computational fluid dynamics (CFD) simulations can provide an inexpensive, flexible method for developing such parameterizations. In this study, the discharge coefficient for pivoted windows is considered, using analytical and CFD modeling as well as comparison with previous data. The discharge coefficient parameterization currently used in EnergyPlus can lead to an underestimate of flow through pivoted windows by up to factor of 2. This parameterization for the discharge coefficient as a function of window angle and aspect ratio is modified, and Reynolds-averaged numerical simulations are used to validate this new formulation. Analytical and numerical results compare well with measurements from window manufacturers.
Pages: 322 - 328