Blower Door Tests

Blower Door Tests

Professional energy auditors use blower door tests to help determine a home's airtightness. Our Energy Saver 101 infographic explains the importance of a blower door test during a home energy audit. 

These 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
  • Determining how much mechanical ventilation might be needed to provide acceptable indoor air quality.

Diagram of a blower door. The parts of the blower door are labeled as follows: exterior door frame (around the outside edge of the door), temporary covering (over the surface of the door), and adjustable frame (just inside the exterior door frame). An air pressure gauge, a small vertical rectangle with three round gauges inside, is alongside of the door. The top gauge is connected by a tube to the temporary covering, and the bottom two gauges are connected to a fan sitting at the bottom of the door. The caption reads: Diagnostic Tools. Testing the airtightness of a home using a special fan called a blower door can help to ensure that air sealing work is effective. Often, energy efficiency incentive programs, such as the DOE/EPA ENERGY STAR® Program, require a blower door test (usually performed in less than an hour) to confirm the tightness of the house.

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. 

Preparing for a Blower Door test

Take the following steps to prepare your home for a blower door Test: 

  • If you heat with wood, be sure all fires are completely out - not even coals - before the auditor arrives. Remove any ashes from open fireplaces.
  • Plan to do a walk-through of your home with the auditor. Be prepared to point out areas that you know are drafty or difficult to condition comfortably.
  • Expect the auditor to request access to all areas of your home including closets, built-in cabinets, attics, crawl spaces, and any unused rooms.
  • The auditor will need to close all exterior doors and windows, open all interior doors, and close any fireplace dampers, doors, and woodstove air inlets.
  • Expect the auditor to set controls on all atmospheric fossil fuel appliances to ensure that they do not fire during the test. The auditor should return them to the original position after the test.
  • Expect the test to take up to an hour or more, depending on the complexity of your home.

Source: U. S. Department of Energy