Advanced Diagnostics: The Blower Door Test

Many homeowners in the Minneapolis and Saint Cloud areas wonder how exactly home performance experts can identify and diagnose a home. The fact is, there are a number of key indicators that can clue contractors in to an underperforming home, some of which are easier to find than others. One of the most important indicators is a lack of air sealing in the home. At RetroGreen, we use a blower door test in order to finding out what’s going on in your home.

New to the concept of the blower door test? Here are a few things to know:

What Is the Blower Door Test?

The blower door test is a diagnostic test used to measure the amount of air leakage occurring within a home. The test itself is comprised of a calibrated fan, mounting system (used to attach the fan to an exterior door) and manometer, which measures pressure. The high-powered fan depressurizes a home, and once this is completed, high pressure air from outside will begin to seep in through unsealed cracks and gaps. From there, we can determine exactly where your home needs air sealing. This strategic approach avoids any speculation about where your home needs an upgrade.

Blower door before insulation and sheet rock

How Is the Test Measured?

The blower door test can be expressed in a few different metrics. More often than not, results are measured by air changes per hour (ACH), which refers to the amount of times a home’s air is completely replaced in a given hour. We take our blower door measurements at 50 Pascal (a measure of pressure), as most codes and standards refer to air changes at this pressure (ACH50), but we’re also able to calculate changes in air pressure under natural conditions (ACHn).

While the numbers can get confusing, Minnesota homeowners can rest easy knowing that the experts at RetroGreen will take care of all the complexities.

Blower Door Scores

Once we’ve received the necessary data, we can effectively score your home on its efficiency and blower door test performance. Common blower door scores include the following:

10-20 ACH50 – Older homes —”like living in a barn.”

7-10 ACH50 – Average new home with some air sealing, but no verification and little attention to detail.

7 ACH50 – Adequate infiltration level, and the 2009 IECC energy code requirement

3 ACH50 – Good and achievable target for most new homes. The ENERGY STAR reference home is 5 ACH50 for climate zone 4, which covers DC, MD, VA and part of PA. The majority of PA is 4 ACH50 for the ENERGY STAR reference home.

3 ACH50 and lower – Tight home with great air sealing, and required by the 2012 energy code adopted in MD and coming to other jurisdictions soon.

.6 ACH50 – Super tight home and the Passive House standard.

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