What's a Blower Door Test?

Professional energy auditors use blower door tests to help determine a home's airtightness or air infiltration rate to find ways to:

  • Reduce energy consumption due to air leakage
  • Avoid moisture condensation problems
  • Avoid uncomfortable drafts caused by cold air leaking in from the outdoors
  • Make sure that the home's air quality is not too contaminated by indoor air pollution.

How Do Blower Doors Work?

diagnostic toolsA blower door is a powerful fan that mounts into the frame of an exterior door. The fan draws air out of the house, lowering the air pressure inside. The higher outside air pressure causes outdoor air to flow freely to the inside through unsealed cracks and openings. The auditors may use a manometer and or smoke stick 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.

It is important that the auditor uses a calibrated door equipped with several gauges that measure the amount of air pulled out of the house by the fan. The calibrated blower door's data allow the auditor to quantify the amount of air leakage and the effectiveness of any air-sealing job.

Source: U.S. Dept. Energy

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