Blower door tests have always been used to help gauge a building’s energy efficiency. But with the passage of the Inflation Reduction Act (IRA) of 2022, these tests are poised to play a more prominent role than ever. That’s because blower door tests will be used to help determine if new and existing single- and multi-family homes qualify for the IRA’s energy efficiency tax credits for homeowners, builders, and building owners.
For example, the IRA extends the 25C Homeowner Tax Credit to include a $150 credit for home energy audits. The IRA also expands the 45L Energy Efficient Home Credit, which allows builders to earn a $2,500 tax credit per unit if it meets or exceeds ENERGY STAR® requirements, and a $5,000 tax credit per unit if it meets or exceeds Department of Energy (DOE) Zero Energy Ready requirements.
These energy efficiency incentive programs have specific climate-zone air infiltration requirements – that is, air that enters the building through leaks in the building envelope. A blower door test measures such leaks in single and multifamily dwellings and must be conducted before and after air sealing. With the significant IRA-related tax credits now on the table, it’s well worth considering how a blower door test works.
Blower Door Test Basics
During a blower door test, a blower door assembly outfitted with a powerful fan is fitted into an exterior door opening. When the fan is turned on, it draws air out of the building to create a low-pressure environment inside. A digital air pressure gauge on the assembly (called a manometer) measures the rate of air exchange or the amount of air leaking into the home.
This air leakage is often expressed as air changes per hour at a specified pressure, usually 50 Pascal, or ACH50. (A 50 Pascal is equal to a 20 MPH wind blowing on the house from all sides.)
Very “tight” buildings have an ACH50 of under 1, while “loose” buildings have an ACH50 over 7. A good target ACH50 for most buildings is 3. For reference, ENERGY STAR residential new construction guidelines require homes to achieve a minimum of 4 ACH50 in climate zones 1 and 2.
In addition to recording the ACH50 numbers captured by the manometer, a blower door test will often involve the use of a non-toxic smoke pencil. This handheld device creates a trail of white vapor that can help an analyst identify air leaks around windows, doors, vents, and other penetrations. Infrared cameras may also detect areas with air leakages and/or poor insulation.
Multifamily Blower Door Tests
The blower test basics described above generally apply to single-family homes and focus on air escaping from the exterior building envelope, or “exterior leakage.” But in multifamily buildings, there are many other potential air leakage pathways. Accordingly, a blower door test on a single unit in a multifamily building will measure some leakage from outside and some “inter-unit” leakage from other areas inside the building.
Multifamily buildings will often have a lot of inter-unit leakages, but in terms of energy efficiency, it’s the exterior leakage that matters most. For this reason, blower door testing in a multifamily building will most often focus on individual units. (It’s also the case that blower door tests for an entire multifamily building are much more complicated and costly than single unit tests).
Still, single-unit blower door tests are valuable, as they will uncover air leakage spots in the building envelope and spots between adjacent units. Both are worth identifying, as controlling building envelope leaks will help boost energy efficiency and limiting leaks between units will maximize temperature control.
Henry® Can Help
Henry offers a range of Building Envelope System solutions that can help builders meet the upcoming IRA-related requirements that will be measured by blower door testing.
Our Blueskin® VP100 and Blueskin VP160 air barrier systems efficiently control air leakage into and out of the building envelope, which in turn can help buildings comply with key industry codes, including Section R402.4.1.2 of 2021 of the International Energy Conservation Code. Blueskin VP100 and Blueskin VP160 can also help achieve and maintain ACH50 values far below the maximum allowed by ASTM E779 or ASTM E1827 testing.
If you need additional advice on meeting blower door test requirements, don’t hesitate to consult with the experts at Henry Company. For 80+ years, our solutions have been helping manage the flow of water, air, and vapor throughout the building envelope. Today, as part of the Carlisle Weatherproofing Technologies (CWT) portfolio of brands, we’re ready to support an integrated building envelope system to improve energy efficiency and help you access credits and deductions offered in the Inflation Reduction Act of 2022.
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