Blower Door Testing | What You Need to Know

You may never have heard of a blower door test. But if you are remodeling a home, or building a new house, you may need to learn. What a blower door machine does is check the air tightness of structures. It can also measure air flow between building zones, check your duct work to make sure you don’t have leaks, and if you do—where they are.

Usually the blower door test is done in homes, but there has been more and more testing of this type done in commercial settings. There are several reasons for this; but the main ones are during energy audits to assess the energy loss from a building, or even to determine if the building could be ‘tight,’ which means there is not enough ventilation through the area.

How Does it Work?

The mechanism is placed in an exterior doorway of the structure being tested. The machine has a variable speed fan, controls, a frame which can be adjusted to fit the door, and devices to measure the difference between the air inside the building and the air outside.

The blower is then calibrated and turned on, the measuring equipment is then able to measure the amount of air being pushed in and pulled out of the building during the test. Using a standard formula, the amount of leakage can be calculated, if there is any.

Setting up the equipment may take some time, but once everything is in place, the actual testing should take about 15 minutes to complete.

What Do the Results Tell You?

Of course, having the information means absolutely nothing unless you understand what the data means. Keep in mind there are many rules and regulations regarding what the information may mean for your home.

Based on guidelines recommended by the HVAC companies, this is what the breakdown of a blower door test can reveal: ACH50 less than 5.0=tight house, ACH50 between 5.0 and 10=moderate house, and ACH50 above 10.0=leaky house.

By looking at the numbers, if your blower door testing is 10, you have holes, cracks, leaky windows, or other problems which allows air to flow very freely from the inside to the outside, or vice versa.

It also means that you are probably paying out a lot of money on high power bills, heating or cooling bills, or you could even have dangerous contaminates leaking into your home. The blower door test is a good idea for new home construction or for old, if you are remodeling or replacing windows.

It is a tool which can help you pinpoint and fix any problems that can affect your home. It can affect your wallet as well during those peak heating or cooling seasons. It can also potentially affect your health by allowing all sorts of things like mold and mildew, or poisonous contaminates into your home. Spending a little on a blower door test can save you a lot of money and frustration later.