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Nonresidential Reduced Infiltration

Measure Description

This CASE Report for reduced infiltration will introduce air tightness elements to the California building energy code since building air leakage testing is currently not a part of mandatory California building codes. This will help demonstrate compliance with the code by investigating two submeasures: air leakage testing and vestibule air leakage. The goal of this combined CASE Report is to eliminate excessive air leakage, especially in exterior entries (vestibules), and improve the overall energy efficiency of nonresidential spaces.  This CASE Report will support air leakage testing and will have a goal to reduce building leakage and as a result generate energy savings, potentially allowing for reduced HVAC equipment sizing, and support building comfort. Specifically, this measure would require the following actions.

Whole Building Air Leakage Testing

This submeasure is proposing a prescriptive requirement for whole building air leakage testing of nonresidential buildings other than high-rise residential. Air leakage rates will be required to not exceed 0.30 cubic feet per minute per square foot of the building thermal envelope area at a pressure differential of 75 Pascals. Construction documents will be required to include all air barrier details. The CASE Team is considering a performance credit for buildings that achieve a leakage below a more stringent threshold.

Vestibule Requirement

This submeasure requires vestibules to be installed in the main entryways of newly constructed nonresidential buildings in order to reduce air infiltration. Vestibules are most effective in achieving energy savings when they are installed in buildings with high occupant turnover. Vestibule installation has been a part of ASHRAE 90.1 and IECC Building Code for over a decade. Exceptions to the vestibule proposal will include air curtain or revolving door installation in addition to exceptions based on the size and location of the building.

Relevant Documents

Measure proposals, supporting documents, and other outside references will be made public as they become available.

Round Two Utility-Sponsored Stakeholder Meeting Materials

Round One Utility-Sponsored Stakeholder Meeting Materials

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This measure description will be updated as research is developed to support the 2022 code cycle. For questions or suggestions, email Include the measure name in the subject line.


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The Statewide CASE Team values input from all stakeholders engaged in the Title 24, Part 6 code change process. We encourage the open exchange of code change comments and concerns.

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