Coupling of Whole-Building Energy, Airflow and Contaminant Transport Models (EnergyPlus and CONTAM) Using Co-Simulation
William S. Dols, Steven J. Emmerich, Brian J. Polidoro
Building modelers need simulation tools capable of simultaneously considering building energy use, airflow and indoor air quality (IAQ) to design and evaluate the ability of buildings and their systems to meet todays demanding energy efficiency and IAQ performance requirements. CONTAM is a widely-used multizone building airflow and contaminant transport simulation tool that requires indoor temperatures as input values, so it is limited in its ability to account for thermal processes upon which building airflow may be significantly dependent. EnergyPlus is a prominent whole-building energy simulation program capable of performing heat transfer calculations, but it has limited capabilities for fundamental physics-based airflow and contaminant concentration modeling. This paper describes the coupling of EnergyPlus with the widely-used whole building airflow and contaminant transport model, CONTAM, using co-simulation. The co-simulation is accomplished through a quasi-dynamic coupling in which EnergyPlus is the Functional Mock-up Interface (FMI) master process and a newly developed tool (ContamFMU) is the FMI slave process. A three-zone combined heat transfer/airflow analytical BESTEST case was simulated to verify the coupling approach as implemented to date is functioning as expected, and an inter-model comparison between the EnergyPlus airflow network model and the EnergyPlus/CONTAM co-simulation capabilities was performed on a two-zone, natural ventilation case designed to challenge the coupled thermal/airflow solution methods.