Trade allies, builders, subcontractors and real estate professionals contact the New Homes team with great questions all the time. Topics range from best practices in new home construction and EPSTM requirements to how to market EPS homes. Below are answers to some of the most common questions about air leakage.
Q: I know it’s a good idea to reduce air leakage in a home, but how is air leakage measured?
A: Measured by performing a Blower Door test, air changes per hour, ACH, is the amount of air leakage in a home. In much of the country, houses built to code have air leakage values around 7 ACH. This is roughly equivalent to a 15″ x 15″ hole in the house, open year-round. With tighter houses, like EPS homes, you can reduce air leakage to around 3 ACH. Some of the best builders in Oregon are commonly reaching air leakage numbers of 1 ACH or less. Tighter homes use less energy and have better indoor air quality—with proper mechanical ventilation installed—than standard code built homes.
Q: Do tighter homes have issues with moisture and indoor air quality?
A: Nowadays indoor air quality can be precisely maintained by incorporating fresh air mechanical ventilation systems. A common ventilation solution is to install a heat/energy recovery ventilator, HRV/ERV. These systems bring in fresh air from the outside and exhaust stale air from the home, while recovering the heat from the exhausted air and transferring it to the incoming fresh air.
Q: When is the best time to conduct a Blower Door test?
A: Most energy-efficiency programs, such as EPS, Home Performance with ENERGY STAR® and Earth Advantage, require that Blower Door testing is done when construction of a house is complete. However, for builders who are new to air sealing or are having trouble getting to low leakage targets, it can be helpful to do a preliminary Blower Door test at rough-in—after exterior sheathing, doors and windows have been installed, but before insulation and drywall installation. Testing during this time can help identify air-sealing opportunities that may be hidden once building cavities are closed up. Many high-performance builders also perform early Blower Door testing to ensure that they seal as many leaks as possible, since it becomes more difficult to seal homes as they near completion. This process requires an air barrier separating the attic from the conditioned living area of the home at the time of the test.
Do you have an energy efficiency or new home construction question we didn’t cover this month? Send it to the New Homes team and it could be included in the next issue of the Insider. Find more about EPS requirements or energy-efficient new home construction on the Online Residential Training page.