Blower door testing (or air leakage testing) is an important part of the building process, as it determines the overall air tightness of a building, and helps to identify problematic leaks that may be present. As a result, it has been required for all new construction and additions since the 2015 IECC was released. Most CO municipalities have adopted the 2015 IECC by now. And many have moved on to the 2018 IECC and 2021 IECC.

When comparing the three different IECC iterations, their air leakage rules are fairly similar. However, the 2021 version of the IECC implemented a very important update with regards to attached single family, multi-family and small dwelling units.

Since more and more counties are moving toward the 2021 IECC standard, it’s a good idea to get acquainted with this update. As blower door testing specialists, it’s our job to stay on top of these things. So we decided to release an article, specifically about the air leakage section. Let’s dive in!

2021 IECC Air Leakage Testing Rules

As stated above, most of the of the air leakage testing rules have remained the same since the 2015 IECC. We have touched on these rules in a past blog. So if you need to get to up to speed, check out this article.

To summarize, a blower door test must be performed in any new construction or addition. All the windows, exterior doors, flues, and vents (where applicable) must be closed or sealed off during the test. The test must be conducted at a pressure of 50 Pascals; and the result must not exceed 3.0 air changes per hour (ACH) or 0.28 cubic feet per minute (CFM) in order to pass. These are tests that our energy services team has been performing throughout the CO Front Range for several years now.

So What’s the Update?

If you take a look at section R402.4.1.2, you will see that an exception has been added for air leakage testing. It reads:

Exception: When testing individual dwelling units, an air leakage rate not exceeding 0.30 cubic feet per minute per square foot of the dwelling unit enclosure area, tested in accordance with ANSI/RESNET/ICC 380, ASTM E779 or ASTM E1827 and reported at a pressure of 0.2 inch w.g. (50 Pa), shall be an accepted alternative permitted in all climate zones for:

1. Attached single-family and multiple-family building dwelling units.
2. Buildings or dwelling units that are 1,500 square feet or smaller.

This new update essentially allows you to utilize a different metric for attached single-family and multiple-family units or buildings that are under 1,500 square feet when testing each unit individually.

When conducting this test, the blower door specialist must measure the area of all floors, ceilings, and walls to the exterior of the dwelling to calculate its surface area. This means that walls/ceilings/floors shared with adjoining units do not need to be included in the surface area calculation. Next, they perform the blower door test at a pressure of 50 Pascals. We then take our total CFM reading, and divide it by the square feet of enclosure area. If the resulting number is at 0.30 CFM/sq ft or lower, the structure has passed the test.

What’s The Difference?

The main difference between the two air leakage tests is dimensions used for each respective formula and how the results are calculated.

For the original test:

The CFM/sq ft is calculated at 50 Pascals, then multiplied by 60 to yield the air changes per hour (ACH). Next, the square footage of the dwelling is multiplied by its ceiling height to calculate the volume of the space. Finally, the ACH is divided by the volume. The answer to this equation must equal 5 ACH or less in order to pass.

For the updated test:

The CFM/ sq ft is calculated at 50 Pascals. Then, the surface area of all floors, ceilings, and walls to the exterior are summed up (remember this excludes walls/ceilings/floors shared with other units). Then the CFM/sq ft is divided by the overall surface area of the dwelling. The resulting number must be 0.30 CFM/sq ft or lower in order to pass.

Is This Update a Good Thing?

Yes it is! This update has proven to be quite helpful for smaller dwellings. Most homes have similar components, regardless of size (i.e. doors, windows, ventilation penetrations, etc.). This means that whether the home is 5,000 sq ft or 1,200 sq ft, it will have to same potential areas for air leakage.

So during the traditional blower door test, a smaller home with the same amount of air leakage as a larger home is going to yield a higher ACH. For this reason small units have a difficult time yielding a passing test score. The updated test has made a passing score more attainable for small homes.

Multi-family and attached single dwellings (such as duplexes) especially benefit from this new exception. In the past, these types of buildings have had difficulty passing due to leakage occurring into adjacent apartments.

However, this type of leakage is not actually occurring to the exterior, and thus not actually an energy loss from the building as a whole. So that type of air leakage is not as big of a concern, from an energy stand point. As a result, the the new air leakage test allows the tester to omit these shared surfaces when calculating surface area.

Learn more about how to best prepare your multi-family building for blower door testing. Check out our article: 7 Tips For Multi-Family Blower Door Testing.

Blower Door Testing Services

Let’s face it, energy codes are strict. And as time passes by, they will probably continue to get stricter. That’s why it helps to have energy pros on your side to help you reach compliance each step of the way. At Scott Energy Services, a division of Scott Home Services, blower door testing is one of our flagship services. With a team of highly trained, experienced and professional energy specialists, we are equipped to help meet your project deadlines.

If you need an air leakage test or any other energy services, we encourage you visit us online or contact our energy service team today!

When the 2015 International Energy Conservation Code (IECC) went into effect, blower door testing became a requirement on all new residential builds and remodels. Prior to this code update, blower door testing had been in use for many years. However, this was the first time that it had become mandatory for many new construction projects.

The International Code Council (ICC) saw it fit to address the issues that can occur with too much air leakage in homes. Therefore, this rule was established as a way to increase energy efficiency in new residential builds.

Counties that have adopted the 2015 IECC (or any later edition) require that any new build must have a blower door test performed by a licensed, third-party company. The results of the test must not exceed the region’s maximum leakage rate in order for the building to be deemed IECC-compliant. It is a crucial aspect of the modern building process in the majority of the nation. So what is blower door testing?

What is blower door testing?

A blower door test is a procedure that involves using specialized equipment to measure the exact air tightness of a home. Depending on the region of the country, a maximum air leakage rate is defined, and each new home must meet this air tightness level.

This technique is the industry standard and is extremely accurate. Furthermore, it not only helps to determine the level of air leakage, it can actually help you to determine the exact sources causing the air leaks.

How does it work?

A blower door consists of a frame and flexible panel that fit into an exterior doorway. A powerful, variable-speed fan mounts into the frame.

All exterior openings – such as doors, windows, flues vents etc. – are closed off or sealed. The fan is then activated to blow air out of the house, lowering the inside air pressure. The higher outside air pressure then flows in through any unsealed cracks or openings.

As the fan runs, an integrated pressure gauge measures the pressure differences between the inside and outside of the home, and an airflow manometer and hoses are utilized for measuring airflow.

The equipment used in the blower door test determines a home’s air infiltration rate, which is measured in air changes per hour (ACH). This is the number that is required by the IECC code. For most Colorado municipalities, the air leakage rate for new residential builds or remodels must not exceed 3.0 ACH.

As the blower door fan runs, the technician is able to walk the house, searching for sources of large leaks. Having conducted thousands of tests, our experts know where to look for primary problem areas. Furthermore, we utilize infrared scanning devices to help detect temperature differentials within the home –  a sign that could indicate air leakage.

A specialist can then help to pinpoint the issues, when present, and relay this info to the project contractor in a timely manner. Find out more about common leaks found during a blower door test here.

Do you need a blower door test performed on your project fast? We can help! Visit our blower door service page to learn more and schedule now.

When do you perform a blower door test?

According to the IECC, the test should “be performed any time after creation of all penetrations of the building envelope have been sealed.” Basically, the home should be as close to being complete as possible, with exterior penetrations sealed properly and all the drywall completely installed, before carrying out the a blower door test.

Any leaks caused by an incomplete building envelope could potentially affect the test results. That’s why the full building envelope needs to be sealed before an accurate test can be conducted.

Who can do the testing?

Here at Scott Energy Services, a division of Scott Home Services, LLC, we proudly offer blower door testing services to the Colorado Front Range. We also offer an extensive list of other energy services including duct leakage testing, insulation inspections, air barrier inspections, full energy audits, Manual J,S &D report preparation, as well as full energy rating services including RES-Check reports and HERS ratings. Check out a full list of our services here.

Is this required in the county you are building in?

Most of the counties along the Front Range of Colorado have moved to at least the 2015 IECC building code by this time. However, we encourage you contact your municipality in order to confirm which code guidelines your building project must adhere to.