Blower Door Tests

Air leakage can lead to air quality problems, energy inefficiency issues, and general discomfort. Pinning down where air leakage occurs, however, is difficult. Enter blower door tests.

A blower door test is a tool used to measure the airtightness of buildings. Blower door tests are important as they help identify areas of air leakage in the building envelope.

How Does a Blower Door Test Work?

Let’s take a step-by-step look at how exactly blower door tests work.

• Preparation. Before conducting a blower door test, all exterior doors and windows are closed, and interior doors are opened to allow airflow throughout the building. If necessary, any combustion appliances (such as gas stoves or furnaces) are turned off to prevent back drafting during the test.
• Testing. The blower door fan is then turned on to depressurize the building, causing air to be drawn out through any leaks in the building envelope. The pressure difference created by the fan is typically standardized to 50 Pascals (Pa), although it can vary depending on the testing protocol.
• Measuring. As the blower door fan operates, the pressure difference between the inside and outside of the building is measured using the pressure gauge. The airflow rate required to maintain the desired pressure difference is also recorded. These measurements provide quantitative data on the building’s airtightness.
• Analysis. The data collected during the blower door test can be used to calculate the air changes per hour, which is a standard metric for assessing a building’s air leakage rate. Additionally, the location and severity of air leaks can be identified by using smoke pencils, infrared thermography, or other diagnostic techniques.

Reporting. The results of the blower door test are documented in a report that highlights areas of concern and recommends strategies for improving the building’s air sealing and energy efficiency.