Blower Door Test

Definition:

A blower door test is a diagnostic procedure used to assess a building’s airtightness by measuring the rate of air leakage through its envelope. This test involves using a powerful fan, temporarily mounted in an exterior door frame, to either pressurize or depressurize the building. By monitoring the airflow required to maintain a specific pressure difference, typically 50 Pascals, professionals can determine the extent of air infiltration and exfiltration. 

Short Description:

A blower door test evaluates how much air leaks into or out of a building, providing insights into its energy efficiency and identifying areas that may need sealing.

Why It’s Important:

Conducting a blower door test is essential for several reasons:

•Energy Efficiency: Identifying and sealing air leaks can significantly reduce heating and cooling costs by preventing unwanted air exchange. 

•Indoor Air Quality: Reducing air leakage helps prevent pollutants, allergens, and moisture from entering the building, thereby improving indoor air quality.

•Building Durability: Minimizing uncontrolled air flow reduces the risk of moisture-related issues, such as mold growth and structural damage, enhancing the building’s longevity.

•Comfort: Blower door tests can diagnose specific areas of the home that might be leaky, empowering occupants and professionals to prioritize specific areas to air seal a home.

Other Things to Consider:

•Preparation: Before the test, all exterior doors and windows should be closed, and interior doors opened. Fireplace dampers and other openings should also be closed to ensure accurate results. 

•Professional Assessment: It’s advisable to have a certified energy auditor or building performance professional conduct the test to ensure accurate measurements and appropriate recommendations.

•Diagnostic Air Sealing: When a professional is air sealing, a best practice is to conduct "blower-door guided air sealing." This means that when the crew is performing air sealing activities (such as adding caulk or other sealants to the attic plane), the blower door is running and measuring - in real time -  the reduction in the building's leakage rate. This can also help diagnose potential problems and solve them in real time. For example, when the blower door is not measuring the amount of air leakage that is expected, the professional may find a previously undiscovered area that needs to addressed. 

•Post-Test Actions: After identifying leakage areas, implementing air-sealing measures, such as caulking and weatherstripping, can improve the building’s performance.

By understanding and addressing the findings from a blower door test, homeowners and builders can enhance energy efficiency, comfort, and the overall health of the living environment.