What is a Blower Door Test?

If you’ve noticed issues with your home insulation, a blower door test could provide valuable insights. This diagnostic tool measures how much air escapes from your house, helping to assess its airtightness. By applying a consistent pressure, the blower door allows for accurate comparisons of air leakage across different homes. During the test, a professional auditor sets up the blower door in an exterior door, depressurizing your home. This process typically takes 2-4 hours, depending on the size of your house. The auditor will walk through your home to prepare for the test, ensuring that all parameters are set for accurate results.

Why Focus on Building Envelope Integrity?

You only get one chance to put together your building envelope correctly. Once concealed with siding and shielding, it becomes nearly impossible to fix. Neglecting this crucial aspect of construction can lead to a leaky home, resulting in poor indoor air quality (IAQ). Moisture deposits on cold surfaces can lead to mold growth, further deteriorating IAQ and potentially causing health issues for residents.Exterior building enclosure leakage significantly impacts our health and well-being. Gaps and cracks in the air barrier allow not only bugs, dust, and pollen but also cold or warm air, moisture, and contaminants to infiltrate your home. In humid climates, excessive leakage can lead to uncomfortable humidity levels and mold growth. Conversely, in drier climates, leaks can lead to dry air that causes discomfort and increases the spread of viruses.

Key Metrics from the Test

Once the blower door test is complete, you’ll receive several important numbers that indicate your home’s air leakage:

• ACH at 50: This stands for “Air Changes per Hour” at 50 pascals. It indicates how many times the total volume of air in your home is replaced in one hour under test conditions.
  • ACH < 5: Semi-tight home
  • ACH 5-9: Moderately leaky home
  • ACH > 9: Very loose and leaky home
  • Lower numbers are better, indicating less air leakage.
• CFM at 50: This refers to “Cubic Feet per Minute” of air moving out of your home at 50 pascals. It helps calculate the ACH.
  • Under 1250 CFM at 50: Tight homes
  • 1300-3000 CFM at 50: Moderately leaky homes
  • Over 3000 CFM at 50: Very leaky homes, common in older structures.
• ACHnat or ENIR (Estimated Natural Infiltration Rate): This term measures the natural air change rate but is often considered less accurate than other metrics.

Interpreting Your Results

Don’t get overwhelmed by the numbers; think of them as reference points for improving your home’s insulation. Choose a qualified professional specializing in blower door testing to ensure accurate assessment and recommendations. Focus on where air is leaking most significantly—leaks around doors may be less critical than those under your home in crawl spaces. Use the results to target specific areas for improvement.

Next Steps

With your blower door report in hand and your auditor’s recommendations, take action to seal and tighten your home. After making energy upgrades, consider scheduling a re-test to verify improvements in your blower door numbers.

The Importance of Blower Door Testing in Construction

Blower door testing is critical whether you are building residential, multifamily, commercial structures, or undertaking restorations or retrofits. Professionals across the industry recognize the need for better duct sealing and improved indoor air quality. The blower door test quantifies air leakage through a building’s enclosure by creating a pressure difference between the inside and outside.These tests define indoor spaces by separating them from the outdoors while quantifying leakage. Remember: you can’t improve what you can’t measure. Once leaks are identified, targeted recommendations can be made for remediation.

When to Conduct a Blower Door Test

Blower door testing is often done near the end of new construction when finishing touches like paint and weather stripping are complete. However, conducting tests at different stages can help identify issues early when repairs are more manageable. To find someone qualified for blower door testing, look for companies specializing in energy code testing or certified energy auditors. Ideally, choose professionals who are RESNET- or BPI-certified.

Achieving an Energy-Efficient Building Envelope

The amount of energy saved by air-sealing depends on various factors like climate zone and indoor temperature settings. The International Energy Conservation Code (IECC) has tightened requirements over time; achieving an ACH50 of 3-5 is now standard practice across most regions. Passive House projects require even stricter standards of 0.6 ACH50.By understanding and addressing air leakage in your home through blower door testing, you can enhance energy efficiency, improve comfort levels, and create a healthier living environment for you and your family.