Leaky homes are hard to heat and hard to cool. The only way to know whether your home is leaky or tight is to measure its air leakage rate with a blower door. A blower door is a tool that depressurizes a house; this depressurization exaggerates the home’s air leaks, making the leaks easier to measure and locate.
An energy-efficient house must be as airtight as possible. Many older U.S. homes are so leaky that a third to a half of the home’s heat loss comes from air leaks.
There is no such thing as a house that is too tight. However, it’s also true that there is no such a thing as an airtight house. Every house leaks, and that’s why we perform blower-door tests — to measure a building’s leakage rate.
Blower-door testing is useful for both new construction and existing homes. By testing a new home, a builder:
If you’re building a new home, the best time to conduct a blower-door test is after the home is insulated but before the drywall is hung. If the test reveals major problems, the leaks will be easier to fix at that point than later on.
There are at least two reasons to conduct a blower-door test on an existing house: to determine how leaky it is, and to help locate and fix the leaks.
When a blower door is used to help an air-sealing contractor locate and fix leaks in an existing house, the procedure is called “blower-door-directed air sealing.” (To see a GBA video of blower-door-directed air sealing, click here.)
During the 1960s, energy experts didn’t realize the extent to which air leakage contributed to residential heat loss. During the early 1970s, however, a few researchers in Sweden, Saskatchewan, and New Jersey…