What Is A Blower Door?

by Erik North on December 29, 2010

blower door


As a professional energy auditor, I use a blower door test to help determine a home’s airtightness and locate the air leaks. There are some reasons for establishing the proper building tightness:

  • Reducing energy consumption due to air leakage
  • Avoiding moisture condensation problems
  • Avoiding uncomfortable drafts caused by cold air leaking in from the outdoors
  • Making sure that the home maintains sufficient fresh breathable air for occupants
    (an aside on this last point; since blower doors create an artificial air loss scenario, they can only approximate necessary levels of fresh air under normal conditions).

What Is A Blower Door – How They Work

A blower door is a powerful fan that mounts into the frame of an exterior door. The fan pulls air out of the house, lowering the air pressure inside. The higher outside air pressure then flows in through all unsealed cracks and openings. The auditors may use a smoke pencil to detect air leaks. These tests determine the air infiltration rate of a building.

Blower doors consist of a frame and flexible panel that fit in a doorway, a variable-speed fan, a pressure gauge to measure the pressure differences inside and outside the home, and an airflow manometer and hoses for measuring airflow.

Combined with an infrared camera, the blower door is a powerful tool for finding and quantifying air transported heat loss.

Previous post:

Next post: