Paper Conference

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


Coupled EnergyPlus and Computational Fluid Dynamics Natural Ventilation Simulation

Rui Zhang, Khee Poh Lam, Shi-Chune Yao, Yongjie Zhang
IBM, T.J. Watson Research Center, Yorktown Heights, NY, 10598
Carnegie Mellon University, Pittsburgh, PA 15213, USA

Abstract: Energy modeling approaches have continued to advance to cater for emerging new design concepts towards“greener” solutions that optimize energy consumption in buildings while maintaining thermal comfort as well as healthy environment. Increasing attention is given to passive and mix-mode systems in building. Computational Fluid Dynamics (CFD) model has been widely adopted as effective tool for natural ventilation simulations. However, CFD become unstable for conjugate heat transfer model, which is the transient heat transfer between solid, e.g., walls, and fluid, e.g., air. Solid and fluid has different respond times. Typically walls respond in hours, and air responds in seconds, causing the system to become stiff. In addressing the issue, a coupled lumped heat transfer model (EnergyPlus) and CFD model (Fluent) was implemented, and 8 days of simulation was conducted. The airflow rates of openings from the airflow network module in EnergyPlus and airflow rates from CFD model were compared. Results show that airflow network model generally predict smaller airflow rates for the openings. Airflow network model generates better results for openings on the south and east facade and internal openings, with difference ranging from −100% to −200%.
Pages: 329 - 336