.IBPSA.Airflow.Multizone.UsersGuide

Information

The package Buildings.Airflow.Multizone contains models for multizone airflow and contaminant transport.

The models can be used to compute the air flow between different rooms and between a room and the exterior environment. In multizone airflow models, typically each room volume is assumed to be completely mixed. The driving force for the air flow are pressure differences that can be induced, e.g., by

• flow imbalance of the HVAC system,
• density difference across large openings such as doors or open windows,
• stack effects in high rise buildings, and
• wind pressure on the building facade.

Wind pressure coefficients for different building configurations can be found in Costola et al. (2009), Persily and Ivy (2001), and Swami and Chandra (1987).

The models in this package are as described in Wetter (2005), except for the addition of the model Buildings.Airflow.Multizone.BaseClasses.windPressureLowRise that computes the wind pressure on facades, and some changes that have been done when migrating the models to Modelica 3.1, which led to a simpler implementation based on the stream functions.

Acknowledgements

We would like to thank the United Technologies Research Center for contributing this package to the Buildings library.

References

D. Costola, B. Blocken and J.L.M. Hensen. Overview of pressure coefficient data in building energy simulation and airflow network programs. Building and Environment. Vol. 44(10): 2027-2036. 2009.

Muthusamy V. Swami and Subrato Chandra. Procedures for Calculating Natural Ventilation Airflow Rates in Buildings. Florida Solar Energy Center, FSEC-CR-163-86. March, 1987. Cape Canaveral, Florida.

Andrew K. Persily and Elizabeth M. Ivy. Input Data for Multizone Airflow and IAQ Analysis. NIST, NISTIR 6585. January, 2001. Gaithersburg, MD.

Michael Wetter. Multizone Airflow Model in Modelica. Proc. of the 5th International Modelica Conference, p. 431-440. Vienna, Austria, September 2006.