Photo of an energy auditor removing an exterior door from our first net-zero home in preparation to perform a blower door test.

There are multiple reasons why a blower door test should be part of the plan when upgrading your home or determining which property to buy. These tests can save homeowners from a lot of trouble in the long term and cut back on expenses.

A blower door test is a method to determine the amount of air leakage from a building and pinpoint leakage points. Getting a blower door test done in your home can help you cut energy costs, prevent rot and mold, raise the value of your home, and improve indoor air quality.

This article will explain what a blower door test is and highlight why every home should have one. I’ll also address how to get ready for the test and give a few pointers on finding experts to help you.

How Does a Blower Door Test Work?

Professional energy auditors do a blower door test, and it takes less than an hour to complete once the equipment is set up. An auditor mounts a fan into the frame of an exterior door. The fan uses suction to suck all the air from the house resulting in a fall in air pressure. (This method is a “depressurization test.”)

Once the pressure outside the building is higher, the auditor switches the fan off. Air from outside flows into the building through all the cracks and openings in the structure, filling the vacuum.

Pressurization Tests

Alternatively, the fan can draw air into the house in what’s called a “pressurization test.” The auditor can then use a smoke pencil to detect air seepage.

In both tests, an infrared camera identifies where warm air or cold air is coming in. Thermal cameras work better when there is a notable difference between the temperature of the air in the house and the air outside.

Types of Blower Doors

Blower doors come in two types: calibrated and non-calibrated.

Out of the two, the calibrated door is more efficient, as it has systems that make it possible to measure the amount of air sucked out of a house. The non-calibrated door can only pinpoint air leakages.

Photo of an energy auditor removing an exterior door from our first net-zero home in preparation to perform a blower door test.
For the blower door to go in, an exterior door has to temporarily come out! Here, an energy auditor removes a door from our first net-zero project to set up for the blower door test.

More About Air Leakage

Few homeowners realize how much air leakage influences utility costs.

Air leakage is measured in Air Changes Per Hour. An ideal ACH reading would be around 3.5 to 4, indicating that the home is reasonably airtight. This kind of reading is mainly found in newer houses. The age of the structure and the level of wall insulation influence the outcome of a blower door test.

Leaks usually occur in jointed areas, which can be anywhere from window frames to eaves. No house is completely airtight, but there should not be any excessive air leakages.

Why a Blower Door Test Is Important for Homes

The information a blower door test gives you about your home can save you a lot of headaches and dollars. Besides helping you save on utility costs, it can make your living more sustainable and more “green” by saving energy and preventing unnecessary waste.

Here are a few reasons blower door tests are so important for homes:

It Helps Save on Utility Costs

If your home has many cracks and spaces where air can escape, you’ll find yourself spending a lot more on heating or air conditioning than you would in an airtight house.

No amount of wall insulation can compensate for air leaks.

Getting a blower door test will help identify leakage points. These can be filled with with spray foam or other materials, or the auditor can suggest ways to seal up the weak points securely. A blower door test pays for itself in the long run.

It Raises the Value of Your Home

Sealing up any holes or cracks makes your home more energy-efficient and “green.” It also helps you meet building code requirements when it’s time to renovate.

Identifying and fixing any air leakage issues in your home will increase the market value of your house and increase its appeal as an energy-efficient haven.

It Prevents Rotting and Mold

The air that leaks out of a house is often very humid.

This moist air finds its way into hidden nooks and crannies in your walls where the moisture is deposited. With time, this can lead to rot and mold and compromise the structure of your home.

Fixing air leakages will prevent your walls from rotting and save you a lot of money on repairs.

It Improves Air Quality in Your Home

Sealing holes and cracks will prevent polluted outside air from getting in your house. Car exhaust fumes, ozone, and lead are all too abundant outdoors, especially in urban settings.

Ideally, the air in your home should be purer than that circulating outside. Your walls should offer protection from contaminants, so identifying and sealing up the holes and cracks will improve the quality of your indoor air.

It Reduces Your Carbon Footprint

The more you use your air conditioning, the more you release the greenhouse gas hydrofluorocarbon, which is the most common refrigerant used in air conditioning units.

If your house has leaks, you’re likely to run your air conditioner more.

Identifying leakages and sealing any cracks will mean that less air will escape, and you won’t have to run your air conditioning for as long or as often.

How To Prepare for a Blower Door Test

After scheduling a blower door test, here’s how to prepare:

  • Set aside a few hours for both the setup and the test.
  • Give the auditor a tour of your house and draw attention to the sections of your home you know are drafty.
  • If your home has fireplaces, ensure that all fires are completely out to avoid any fire hazards.
  • Every room, closet, and space must be accessible to the auditor.
  • Expect the auditor to close and secure all doors and windows that lead outside, open the rest, and secure all other openings.
  • Turn off all air conditioners and fans before the blower door test begins.

If you need to know more about blower door testing, the benefits, and how it works, here’s an informative video you can watch:

How To Get a Blower Door Test Done

Only experts should perform blower door tests, although a homeowner can note down any drafty areas before the auditors come to do the test.

Check with your closest power company or contact certified professionals near to your location, and they can do the job for you. A blower door test for a regular-sized home should cost no more than $500, though some power companies offer blower door testing at a discount rate for customers.

Final Word

Getting a blower door test is a necessity if you want your house to be as energy efficient as possible. It helps to identify air leaks that drive up utility bills.

Blower door tests can also help boost the market value of your home, enhance the ventilation and quality of air in your home, and gauge the airtightness of your home.

An airtight home is a sustainable home. If you want to do your part to save the planet, a blower door test is an investment worth making.

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