Nov 19, 2019

Airtight Done Right: Sealing with aerosol

Dave Bohac, PE

This article was written by Amanda Voss for Energy Design Update, with heavy contribution from Dave Bohac, CEE's Director of Research. The article profiles Bohac's aerosol sealant research.


The American home is responsible for about 23% of energy use in the United States, and 43% of that energy use is dedicated to heating and cooling. For current homes, the US Department of Energy (DOE) estimates that 29% of space conditioning use results from air infiltration. Of the 135,000 homes in the US Residential Diagnostics Database (ResDB;, there was a geometric mean leakage of 11 air changes per hour at a pressure difference of 50 Pascals (ACH50). This unintended air infiltration results in additional space heating and cooling equipment loads, as well as loss of comfort and uncontrolled airflow in homes.

How to get homes airtight is not only a debate in the laboratory, but also a constant challenge in the field. Even the best traditional sealing methods are manual, making them costly in time and labor and hard to verify. A builder must rely on contractor personnel to visually identify and manually seal leaks individually, which means that the ultimate airtightness level is highly variable. Often, airtightness verification is performed by yet another contractor after the sealing work, and after most (or all) of the construction is complete. This provides limited opportunity for feedback on the effectiveness of the air sealing, making it difficult for the sealing contractor to ensure that a specific level of tightness has been achieved. “Even a 10% to 30% reduction goal is challenging,” says Dave Bohac, director of research for the Center for Energy and Environment (CEE). CEE is also one of the DOE’s Building America research teams, working to further develop the aerosol envelope-sealing technology.