This proposal would expand the current prescriptive continuous air barrier requirements to additional climate zones. It would also strengthen requirements to affirm air barriers are effective by requiring verification. Currently, continuous air barriers are a prescriptive requirement in newly constructed buildings in Climate Zones 10 through 16. This code change would expand this requirement to all building types – including hotels – in all climate zones for new construction, additions, and altered building envelope components.
The proposed code change would offer two options to demonstrate the air barrier is installed correctly: 1) whole-building air leakage testing, or 2) visual inspection. Using the whole-building air leakage test option, the test must confirm the air barrier is effective at limiting leakage to 0.4 cubic cfm/ft2 when pressurized to 75 Pascals (Pa). If the measured leakage is 0.4 cfm/ft2 or below, the building passes the test and is compliant with the code. If the measured leakage is above 0.4 cfm/ft2 the following corrective actions would be required:
- Locate sources of leakage using a smoke tracer test or infrared imaging survey.
- Implement corrective actions to seal leaks.
- Report corrective actions taken and provide justification for any leaks that were not sealed.
If the measured leakage was above 0.6 cfm/ft2, the leakage test must be repeated after the corrective actions to verify leakage is below 0.6 cfm/ft2.
Nonresidential Appendix NA2.4 would be added to describe the whole-building air leakage procedure, which would reference tested in accordance with American Society for Testing and Materials Standard Test Method For Measuring The Air Leakage Rate Of A Large Or Multizone Building (ASTM E3158). Small buildings with less than 10,000 ft2 of conditioned space can use test procedures described in Residential Energy Services Network Standard 380 (RESNET 380). Large buildings with a conditioned floor area of 50,000 ft2 or more would be allowed to use a sectional test method approach in accordance with ASTM 3158 (previously established by ASRHAE 90.1 – 2019).
The second option to verify the air barrier installation is to have an independent third party complete a field verification to inspect the air barrier while it is being installed. The visual inspection procedures are described in the newly added NA2.5.
The proposed code changes for air barrier verification would apply to all nonresidential buildings except for those in Climate Zone 7, including new construction, additions, and alterations when over 50 percent of the building envelope is altered. In the case of an additions, only the added partition would have to comply with the air leakage testing requirement. For healthcare facilities, the proposed code changes would apply to new facilities and additions but not to alterations.
The Energy Commission has indicated it is unlikely that they will accept the recommendation to require air barrier verification citing the challenges associated with creating and maintaining qualification criteria for qualified third-party entities to conduct the verifications. Verifying air barriers will result in cost-effective energy savings, including significant natural gas savings. The Statewide CASE Team continues to support the verification requirements presented in this report and is interested in working with the Energy Commission and other stakeholders to develop the infrastructure needed to implement the recommended requirements.
The proposal would recommend revisions to the leakage rates used in the Standard Design and Proposed Design in the compliance software.
Finally, the proposed code change would require the air barrier details to be included in construction documents to help improve compliance verification.
 The continuous air barriers must either use materials with an air permeance below 0.004 cfm/ft2 at 75 Pascals (Pa), use assemblies of materials and components with an air leakage below 0.04 cfm/ft2 at 75 Pa, or conduct a whole building leakage test to confirm that air leakage of does not exceed a rate of 0.4 cfm/ft2 measured at 75 Pa.
 Section 100.1(b) of Title 24, Part 6 includes the following definition, “RESNET 380 is the Residential Energy Services Network document titled “Standard for Testing Airtightness of Building Enclosures, Airtightness of Heating and Cooling Air Distribution Systems, and Airflow of Mechanical Ventilation Systems” 2016 (ANSI/RESNET/ICC 380-2016).” If a residential building using the performance approach uses air leakage rates that are less than those used in the Standard Design to comply with Title 24, Part 6, then the leakage rate must be verified (Section 150.1(b)3Bviii). The test procedure for residential air leakage testing is described in Residential Appendix RA3.8 Field Verification and Diagnostic Testing of Air Leakage of Building Enclosures and Dwelling Unit Enclosures and references RESNET 380.
Submeasures Moved to Future Code Cycles
The Statewide CASE Team is no longer pursuing the proposed changes listed below because at the time of consideration it was determined the measure would not result in sufficient savings within California climate zones.
This submeasure would have required vestibules 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.
Materials that the Statewide CASE Team developed when investigating this code change for the 2022 code cycle will be moved to the Future Code Cycles section of this website. Follow this link to find materials on the vestibule requirement.
Measure proposals, supporting documents, and other outside references will be made public as they become available.
- Final CASE Report – Nonresidential Reduced Infiltration
- Draft CASE Report – Nonresidential Reduced Infiltration
Round Two Utility-Sponsored Stakeholder Meeting Materials
- Nonresidential Reduced Infiltration Submeasure Summary
- Presentation – April 14 – Nonresidential and Single Family Part 2
- Notes – April 14 – Nonresidential and Single Family Part 2
Round One Utility-Sponsored Stakeholder Meeting Materials
Give Us Your Feedback
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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