A blower door test is used to measure a building’s airtightness and identify air leakage points. It helps determine how much air is entering or escaping the building, which is critical for evaluating energy efficiency. The results can guide improvements to insulation, reduce energy waste, and enhance indoor air quality.

A blower door consists of a powerful fan temporarily mounted in an exterior doorway. The fan pulls air out of the home, creating a slight vacuum. As a result, higher outside air pressure forces air through unsealed gaps, cracks, and openings. A manometer measures this airflow to calculate the air infiltration rate—typically reported in air changes per hour (ACH).

While the test is underway, Alpine Energy Solutions (AES) may use an infrared camera to inspect walls, ceilings, and floors, helping pinpoint areas where insulation is missing or air is leaking.

Blower door tests can be conducted during construction or renovation to:

• Measure baseline leakage before air-sealing work begins

• Verify improvements after air-sealing has been completed

Blower door testing is a vital part of energy audits and is often required for code compliance in modern building standards. It ensures buildings meet energy performance goals for both comfort and efficiency.

Preparing for a blower door test involves several steps to ensure accurate results and to protect your property during the test.

AES will perform the blower door test, including a walk-through of your home, setting up the blower door, and conducting the test. The following steps will help prepare your home for a blower door test:

1. Plan to do a walk-through of your home with AES. Be prepared to point out areas that you know are drafty or difficult to condition comfortably.

2. Expect AES to request access to all areas of your home including closets, built-in cabinets, attics, crawl spaces, and any unused rooms.

3. To prepare for the blower door test, AES will close all exterior doors and windows and open all interior doors. This ensures that air isn’t drawn in through unintended pathways and that the entire interior space is included in the test.

4. If you heat with wood, be sure all fires are completely out and remove any ashes from open fireplaces.

5. Turn off heating, ventilation, and air conditioning (HVAC) systems, exhaust fans, and combustion appliances like gas water heaters, furnaces, and fireplaces to prevent damage and ensure safety.

A duct leakage test is designed to measure the airtightness of the ductwork in a heating, ventilation, and air conditioning (HVAC) system. The purpose of this test is to identify leaks in the ductwork that can lead to energy losses, reduced system efficiency, and compromised indoor air quality.

Similar to a blower door, a duct leakage test utilizes a fan to pull a vacuum pressure on all supply and return ductwork. The amount of air required for the vacuum pressure is then used in the calculation to determine a percent leakage rate. As with the blower door test, a duct leakage test is a requirement for most new construction.

Per the 2021 IECC, ducts shall be pressure tested by either a Rough-in test or a Final test. It is recommended to perform this test during the rough-in stage, as all ductwork will be easily accessible if further sealant needs to be installed for passing results

AES will seal off all of the return and supply registers in the building and install a fan to de-pressurize the ductwork system. The sealing of registers is accomplished by using a specialty tape, similar to saran wrap. The fan is then sealed to the air handler or large return opening and the test can commence.

Per the 2021 IECC, for the blower door, a passing test concludes that the building has less than or equal to 3 air changes per hour (Climate Zones 3 through 8).

For the duct leakage test, during rough-in, a passing test concludes that the total leakage is less than or equal to 4 cubic feet per minute per 100 square feet of conditioned floor area. If the air handler is not installed at the time of the test, the total leakage shall be less than or equal to 3 cubic feet per minute per 100 square feet of conditioned floor area.

If the duct leakage test is performed postconstruction, total leakage shall be less than or equal to 4 cubic feet per minute per 100 square feet of conditioned floor area.

When all ducts and air handlers are located entirely within the building thermal envelope, a passing test concludes total leakage to be less than or equal to 8 cubic feet per minute per 100 square feet of conditioned floor area.

If this is your first test, always have it performed at the rough-in stage so that issues can be easily addressed. Passing a duct leakage test involves ensuring that your ductwork is as airtight as possible. Here are some helpful hints to prepare for and pass your duct leakage test:

• Inspect Ductwork: Before the test, thoroughly inspect all ductwork for visible signs of damage, gaps, or poorly connected joints. Pay special attention to areas where ducts connect to vents, registers, and the HVAC unit.
• Liquid Mastic or “pookie” has shown the best results for sealing any type of joint.
• Seal every joint. The test is very sensitive, so the HVAC professional may need to seal quite a bit more than normal.
• The furnace or air handler is often overlooked. Seal around the edges and around the back side of the handler where the returns connect.
• Flex duct is popular in attics. However, the zip ties conjoining them to the system have a tendency to leak. Add mastic to these joints as well to create a tight seal.
• Make sure the filter cover is fully installed and sealed before the test.

It can be helpful for the HVAC installer to be present during the inspection to help identify and repair leaks on the spot.