CHAMPS-Multizone—A combined heat, air, moisture and pollutant simulation environment for whole-building performance analysis

Abstract

Abstract A computer simulation tool, named "CHAMPS-Multizone," is introduced in this article for analyzing both energy and indoor air quality (IAQ) performance of buildings. The simulation model accounts for the dynamic effects of outdoor climate conditions (solar radiation, wind speed and direction, and contaminant concentrations), building materials and envelope system design, multi-zone air and contaminant flows in buildings, internal heat and pollutant sources, and operation of the building HVAC systems on the building performance. It enables combined analysis of building energy efficiency and indoor air quality. The model also has the ability to input building geometry data and HVAC system operation related information from software, such as SketchUp and DesignBuilder via IDF file format. A "bridge" to access static and dynamic building data stored in a "Virtual Building" database is also developed, allowing convenient input of initial and boundary conditions for the simulation and for comparisons between the predicted and measured results. This article summarizes the mathematical models, adopted assumptions, methods of implementation, and verification and validation results. The needs and challenges for further development are also discussed. Acknowledgments Wei Feng, Student Member ASHRAE, is PhD Candidate and. John Grunewald is Professor. Andreas Nicolai, PhD, is Research Scientist. Carey Zhang is Research Assistant. J. S. Zhang, Member ASHRAE, is Professor. Notes Alternatively, the building envelope model can calculate flux terms from interior surface into zones, and then the zone model uses the calculated fluxes for zone balance calculation. However, the zone model turns out to have better numeric convergence and stability when using the interior surface state variable (temperature, concentrations) compared with using fluxes. The small error at a low heat load in the morning is potentially caused by (1) the variant from solar radiation model output or (2) the different solving methods that CHAMPS-Multizone and EnergyPlus use to solve long-wave radiation. For details, please see EnergyPlus Development Team (2010).