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NIST infiltration correlations

The Department of Energy (DOE) estimates that air leakage (or “infiltration”) through building envelopes accounted for 6 % of the total energy consumed by commercial buildings in 2010 (DOE 2014). Air barrier requirements are now included in ASHRAE Standards 90.1 and 189.1. Read more about infiltration here.

Given the energy impacts of unintended infiltration on building energy use NIST has been developing tools to better account for infiltration in building energy models. One of these tools was the development of weather-correlated infiltration inputs (or “NIST infiltration correlations”) (Ng et al., 2021)Below describes the building models used to develop the correlations, the available datasets and publications on the correlations, and a link to the video and written tutorials on how to implement them.

Commercial building models & NIST infiltration correlations

In 2011, DOE released a set of 16 commercial reference buildings (Deru et al. 2011) for EnergyPlus to assess new technologies and support the development of energy codes in pursuing building energy efficiency improvements. The models represented buildings that were constructed before 1980, constructed between 1980-2003, and constructed in 2004. In 2014, the models were updated (Goel et al. 2014) so that the modeled buildings comply with newer versions of ASHRAE Standard 90.1 Energy Standard for Buildings Except Low-Rise Residential Buildings and the International Energy Conservation Code. The table below shows the reference/prototype model by year and if the NIST infiltration correlations are available for them:

DOE reference and prototype commercial buildings and availability of NIST infiltration correlations
Building type NIST infiltration correlations available for 2004 version NIST infiltration correlations available for 2013 version
Restaurant - Full Service  
Restaurant - Quick Service    
Healthcare - Hospital
Healthcare - Outpatient    
Hotel - Small
Hotel - Large  
Office - Small  
Office - Medium
Office - Large  
School - Primary
School - Secondary  
Retail - Stand-Alone
Retail - Strip Mall  
Retail - Supermarket   DOE model not released
Apartment - Midrise  
Apartment - Highrise DOE model not released


Detailed methodology on how the NIST infiltration correlations were developed can be found in the publications listed at the bottom of this page. In summary, the correlations were developed using CONTAM simulation results for the building types listed above, two different building envelope airtightness values, and eight cities following the diagram below.

NIST correlations methodology flow diagram
NIST infiltration correlation process
Credit: Lisa Ng/NIST

The airtightness level used in these correlations were:

  • 3.8 L•s-1•m-2 or 0.75 cfm•ft-2 at 75 Pa (5-sided values)
  • 1.4 L•s-1•m-2 or 0.27 cfm•ft-2 at 75 Pa (6-sided values)

Datasets, publications, and tutorials 

Created September 28, 2023, Updated October 4, 2023