What Is A Good Blower Door Test Score:


As energy efficiency and sustainable living gain prominence, blower door tests have become a standard procedure in assessing a building’s airtightness. But what exactly constitutes a good blower door test score? In this article, we’ll delve into the fundamentals of blower door testing, what the scores mean, and how to interpret the results to ensure a more energy-efficient, comfortable, and cost-effective living space.

Understanding Blower Door Testing

Before discussing what constitutes a good blower door test score, let’s first understand the basics of this evaluation:

  • Blower Door Test: A blower door test is performed to measure a building’s airtightness. It involves using a powerful fan to depressurize or pressurize the building, causing air to flow in or out through gaps, leaks, or weaknesses in the building’s envelope.
  • Air Changes per Hour (ACH): The primary metric used to assess the airtightness of a building is the number of air changes per hour. An ACH value indicates how many times the air within the building is exchanged with outdoor air in an hour when a pressure difference is created.

What Is a Good Blower Door Test Score?

The term “good” can vary depending on several factors, including building type, climate, and local building codes. However, here are some general guidelines:

  1. Residential Homes:

    • For a typical residential home, an ACH value of 3 or lower is often considered good. This indicates a relatively airtight building with minimal air leakage.
    • An ACH value between 3 and 5 is considered acceptable, while values above 5 may suggest room for improvement.
  2. Energy-Efficient Homes:

    • In energy-efficient or passive homes designed for minimal energy use, a target ACH value of 0.6 or lower is often sought. Achieving nearly airtight conditions is vital for these highly efficient homes.
  3. Commercial Buildings:

    • For commercial buildings, the criteria can differ. An ACH value of 2 to 4 may be considered good, but it’s essential to consult local building codes and standards for specific requirements.

Interpreting the Results:

When interpreting blower door test scores, consider the following:

  • Climate: Buildings in colder climates may have different ACH targets compared to those in milder regions. Insulation requirements and potential moisture concerns can influence the desired score.
  • Building Type: Different building types, such as residential, commercial, or industrial, may have distinct standards for acceptable ACH values.
  • Local Codes: Always check local building codes and standards. They often dictate the acceptable ACH values required for new construction or renovations.
  • Energy Goals: Consider your energy efficiency goals. If you’re striving for a net-zero or passive house, your target ACH value will be much lower.
  • Airtightness Measures: While ACH values are vital, it’s equally important to assess the overall airtightness measures within your building. Some air leakage may be acceptable in specific areas.

Conclusion: Prioritize Energy Efficiency

In conclusion, the definition of a good blower door test score is context-dependent, influenced by factors such as building type, location, and energy efficiency goals. Regardless of the numeric score, the underlying goal remains the same: to minimize air leakage, enhance energy efficiency, improve indoor comfort, and reduce energy costs. Prioritizing airtightness in your building is a vital step toward creating a sustainable and eco-friendly living or working environment.