Energy Efficiency Series: Blower Door Basics

In our energy efficiency series of articles featured each Thursday, we provide strategies or information on how to make your new home energy efficient and comfortable. 

How leaky is your house? The only way to know whether your home is leaky or tight is to measure its air leakage rate with a blower door. By measuring the airflow of a fan that depressurizes a house to a standard pressure difference, a technician can determine just how leaky your home is. The photo shows a Minneapolis blower door from The Energy Conservatory.

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.

Who needs a blower door?
Blower-door testing is useful for both new construction and existing homes. By testing a new home, a builder:

  • Can determine whether a certain airtightness target — for example, the Passivhaus airtightness standard — has been met;
  • Can document airtightness levels needed to qualify for certain home labeling programs, including Energy Star;
  • Can do a better job calculating heat loss and heat gain the next time he or she builds a similar house;
  • Can brag about the home’s airtightness to prospective homebuyers or drinking buddies.

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.

Want to learn more about the origin of the blower door test and where leaks are typically found? Read the full article here…

Each Thursday, we will feature a blog entry about energy efficient new homes, covering a range of topics from building innovations to ratings systems to “score” your home’s efficiency. Subscribe to theDrummondHousePlans blog to make sure you get the latest news on how to make your new or renovated home energy efficient.


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