BlowerDoor

Blower Door Tests

Professional energy auditors use blower door tests to help determine a home's
airtightness. The test attaches a fan to the outside door. The fan pulls air out of
the house to lower the inside air pressure. Air from the outside flows in through
any openings. While the air is being pulled out, the auditor can see where the
leaks are occurring.

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
Making sure that the home's air quality is not too contaminated by indoor air
pollution.
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.

There are two types of blower doors: calibrated and uncalibrated. It is important
that auditors use a calibrated door. This type of blower door has several gauges
that measure the amount of air pulled out of the house by the fan. Uncalibrated
blower doors can only locate leaks in homes. They provide no method for
determining the overall tightness of a building. The calibrated blower door's data
allow the auditor to quantify the amount of air leakage and the effectiveness of
any air-sealing job.