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An improved method of modeling infiltration in commercial building energy models



Lisa C. Ng, Steven J. Emmerich, Andrew K. Persily


As various strategies for improving building envelope and HVAC equipment efficiencies are increasingly used to reduce building energy use, a greater percentage of energy loss can occur through building envelope leakage. Although the energy impacts of unintended infiltration on a building’s energy use can be significant, current energy simulation software and design methods are generally not able to accurately account for envelope infiltration and the impacts of improved airtightness. A new strategy to incorporate airflow calculations into building energy calculations is proposed, which is more accurate than current estimation methods but easier to apply than multizone airflow modeling. This approach is based on relationships between infiltration rates calculated using detailed multizone airflow models and building characteristics, including envelope airtightness, weather conditions and system operation.
Technical Note (NIST TN) - 1829
Report Number


airtightness, energy, infiltration, modeling, multizone, simulation


Ng, L. , Emmerich, S. and Persily, A. (2014), An improved method of modeling infiltration in commercial building energy models, Technical Note (NIST TN), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed April 15, 2024)
Created April 28, 2014, Updated November 10, 2018