The Blower Door Test: How it's Performed and What it Can Tell You – Sobieski Services | DE, NJ, PA, MD

The Blower Door Test: How it’s Performed and What it Can Tell You


Sealing air leaks in your home’s exterior envelope can improve it’s overall efficiency and help you save energy. One of most effective ways to locate leaks that need attention is having a home energy audit performed that includes a calibrated blower door test.

What is a Blower Door?

This specialized tool consists of a paneled, portable door frame that’s fitted with a powerful fan, a pressure gauge and an airflow manometer. When a test is performed, the frame is installed in one of a home’s exterior doorways. Then, all the home’s windows and other exterior doors are closed, as well as the air inlet on a woodstove, and the fireplace damper. The interior doors are opened, and any combustion appliances are adjusted so they don’t ignite during the test.

What Happens During the Test?

Once everything is closed up and the blower unit is in place, the fan is turned on to pull air out from inside the house, which lowers the indoor air pressure. To compensate for the pressure difference, outdoor air gets pulled in through any cracks and leaks in the exterior shell. While the house is depressurized, the technician usually goes from room to room with a smoke pencil to precisely locate the leaks where air is entering.

What Does a Blower Door Test Reveal?

In addition to revealing the location of air leaks through the envelope, a calibrated blower door test can also be used to calculate the air leakage rate in cubic feet of air per minute. When this rate is compared to the size of your home, it tells the technician how many air changes per hour (ACH) are occurring. After all the identified leaks are sealed, you can have a second test done and compare the two ACH measurements to learn how much of an improvement was made.

At Sobieski Services, Inc., our goal is to help our customers in Delaware, Pennsylvania, Maryland and New Jersey learn more about energy and home comfort issues — especially HVAC and plumbing issues — so that they can save money and live in healthier, more comfortable homes.

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