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Building America Team: Center for Energy and Environment

Partners: Aeroseal, LLC; University of California, Davis; and Western Cooling Efficiency Center

Photo of an aerosol spray in a building.
Illustration of three houses and how the aerosol spray is used.

Manual methods for sealing leaks within a building, even when diligently applied, can fall short of the ultimate tightness goal because of unrecognized or inaccessible leakage pathways. The aerosol envelope sealing technology developed by the Western Cooling Efficiency Center at UC Davis uses an automated method to satisfy the envelope sealing requirement. A number of demonstrations in new construction for both multifamily and single-family homes showed the ability to reduce air leakage by 60% to 85% in less than two hours.

Adapting an automated aerosol envelope sealing technology for use in existing residences may more quickly and cost-effectively eliminate leakage pathways.

The aerosol sealing process involves pressurizing the building while applying an aerosol sealant “fog” to the building interior (see photograph). As air escapes the building through leaks in the envelope, the sealant particles are carried to the leaks where they make contact and stick, sealing the leaks. A standard blower door fan is used to pressurize the house, and also provides real-time feedback and a permanent record of the sealing that occurred. The technology is, therefore, capable of simultaneously measuring, locating, and sealing leaks in a house.

This project will identify the best methods for aerosol envelope sealing of existing residences. There are numerous unresolved issues that need to be addressed for widespread application and market adoption of this process. The project team will develop new sealant formulations that are better suited to existing buildings and perform sealing on 30 to 35 existing homes to evaluate surface protection methods that allow successful sealing while limiting cleanup costs, inspection procedures to identify larger gap leaks that the aerosol will not seal, alternative spray configurations (e.g., attic spray with house depressurization), and possible approaches for sealing exterior duct leaks. The findings will be used to develop a best practice guide for cost-effective aerosol envelope sealing of existing homes and multifamily units.