WHY SHOULD I HAVE A BLOWER DOOR TEST PERFORMED?
As equally important as the duct leakage test, this test is imperative to anyone who is concerned with indoor air quality and electric bills. “Infiltration” is the term used in the industry to express the flow of air into and out of a home. Thus, the leakier your home, the more money will be spent on conditioned air being forced outside through leaks, as well as unconditioned and possibly contaminated air being drawn inside your home through leaks. In addition, air leaks can contribute to more than 30% added expense for cooling and heating a home. Although all homes have some leakage, there are techniques that should be utilized during all new construction, to avoid unnecessary leakage. However, these techniques that can and should be applied to existing homes (sometimes called Retro-fit upgrades or Weatherization) as well. Usually leaky doors and windows are the first leaks that come to mind, please refer to the pie chart below that shows air leaks in a typical home.
Just as important to knowing how leaky a home is, it is equally important to know how tight a home is, a tighter than normal house can cause indoor air quality issues too. With the newest of building codes which applies to all new homes, building scientist have found that this has caused a home to become so tight, that fresh air MUST BE BROUGHT IN! This is accomplished with mechanical ventilation devices.
HOW IS A BLOWER DOOR TEST PERFORMED?
An envelope tightness test is conducted using a diagnostic calibrated fan, mounting hardware and pressure manometer. This fan is then placed in an exterior doorway using a metal frame with the opening completely covered with a vinyl cloth. (see the image below). This fan in motion, forces the air out of your home. Scientifically speaking, the house is then depressurized to 50 Pascals or 50 PA. While the air is being forced out of the home, it is inadvertently drawing air into the home through all the cumulative leaks. (as shown on the chart above.) The manometer uses pressure readings to measure just how much air is being drawn into the home to keep the pressure equal at 50 pa’s. This info and then be calculated into how large the cumulative leaks are on a home.
Currently, the blower door test will be required for all new construction beginning June 30, 2017.
Here’s what a Blower Door Test looks like