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Consideration of Envelope Airtightness in Modelling Commercial Building Energy Consumption



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


As strategies for improving building envelope and HVAC equipment efficiencies are increasingly required to reduce building energy use, a greater percentage of energy loss will 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. The airflow analyses capabilities of several energy simulation software are summarized, including whether the program calculates airflow rates for the user or accepts them as inputs. The bases of these airflow rate estimation approaches are evaluated for their physical soundness and accuracy. A new strategy to more accurately incorporate airflow calculations into energy software is also proposed, which is based on relationships between building infiltration rates calculated using detailed multizone airflow models and building characteristics, weather conditions, and building envelope airtightness.
The International Journal of Ventilation


Commercial buildings, energy, envelope airtightness, indoor air quality, infiltration


Ng, L. , Persily, A. and Emmerich, S. (2014), Consideration of Envelope Airtightness in Modelling Commercial Building Energy Consumption, The International Journal of Ventilation, [online], (Accessed June 17, 2024)


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Created March 26, 2014, Updated February 19, 2017