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CHIMP is the Clearing House for Infiltration Modeling Purposes. This image shows the word CHIMP inside a building, with arrows penetrating the walls to represent infiltration.
Credit: Lisa Ng/NIST

What is CHIMP?

CHIMP is the Clearing House for Infiltration Modeling Purposes, which provides a central resource where users can obtain information, data, and tools to facilitate the modeling of infiltration in a variety of analysis tools (e.g., CONTAM, EnergyPlus, etc). Since 2012, NIST has been developing models, datasets, and tools for estimating the effects of infiltration on heating, ventilating, and air-conditioning (HVAC) related energy use. CHIMP is the one-stop shop for your infiltration modeling needs and is updated when new work is released. To get notified of updates to this page, please email [at] (lisa[dot]ng[at]nist[dot]gov)

What can I find on CHIMP? 

CHIMP is repository of major infiltration-related products developed by the NIST IAQ and Ventilation Group. These products are:

  • NIST infiltration correlations: These inputs can be used in EnergyPlus (and other building energy simulation software) to account for infiltration in energy simulations.
  • OpenStudio Measure: This measure allows the OpenStudio user to seamlessly incorporate the NIST infiltration correlations into their project.
  • Energy Savings and Moisture Transfer Calculator: An online diagnostic tool to evaluate the effects of airtightening on HVAC-related energy use and moisture transfer into buildings (developed with Air Barrier Association of America, US-China Clean Energy Research Center for Building Energy Efficiency, and Oak Ridge National Laboratory).
  • CONTAM Results Export Tool: An online tool that converts CONTAM simulations results (i.e., binary result files) and converts them to tab-delimited text files that can be read using a spreadsheet program. As part of this tool, users can export whole-building or zone-specific air change rates for use in EnergyPlus.
  • CONTAM video tutorials and airflow 101: Here are a collection of videos that show users how to use to CONTAM and an illustrated video on building airflow physics, which includes what is infiltration.
  • Future: Commercial Building Airtightness Database

What is infiltration? 

Infiltration is the unintended and uncontrolled air leaking into a building through intentional and unintentional openings. Due to mass balance, air is also leaving a building through intentional and unintentional openings (exfilftration) [read more].


Created September 28, 2023, Updated October 4, 2023