In this short video, Vermont-based home-performance consultants Jim Bradley and Chris West used a high-volume theatrical fog machine to fog the interior of the newly built 2,000-square-foot house in northern Vermont—after the home’s primary air barrier was completed. They pressurized the home with a blower door to push out the fog, then inspected the home’s exterior perimeter for air leakage.

Tightening up your game (in VT). As of September 1, 2020, Vermont implemented new 2020 Residential Building Energy Standards (RBES). Blower door testing by a certified tester is now required for the RBES Base and Stretch codes. All newly built homes will be required to be blower door tested for air leakage to certify a maximum of 3 ACH (air changes per hour) or lower — it’s no longer just a visual inspection. “Self-certifying” is allowed, but in Vermont, all testers must be certified through the Building Performance Institute (BPI) or Efficiency Vermont.

Regarding national trends, Chris West notes, “Vermont is one of only 10 states that is implementing the IECC rules as is, the rest of the states are below that. Nationally, the trends are heading in a good direction, but overall implementation is lagging.”

For more on using this technique, see "Tracing Air Leaks with a Blower Door."