Gaines Group Architects

Green Terms Defined: Air Infiltration

InfiltrationInfiltration – The uncontrolled inward air leakage through cracks and holes in the building envelope and around windows and doors of a building. Its typically caused by the pressure effects of wind and/or the effect of differences in the indoor and outdoor air density. This can be a garage door opening or even a light breeze against a garage door, a forced air heating and cooling system, or unbalanced pressures room to room in a home.

This time of year, comfort issues in your home are highlighted while we all try to stay warm. A breeze running down a wall, under a door, or from an attic access makes it really hard to be comfortable. This comfort issue is a big signal that you have energy-efficiency issues in your home. Finding the leaks and plugging the leaks will not only make your home more comfortable, it will reduce your monthly electric bills. The best way to find the leaks is doing a blower door test and using thermal imaging technology. However, a smoke stick or even a candle can identify the big leaks.

Tired of High Electric Bills? Get the Test!

energy testIf you are ready to fight back against those high energy costs or simply want your house to be more comfortable, you should consider hiring an energy auditor. They are able to test your home to determine where the problems are and give you a list of things to address. Don’t fall for the sales pitch of replacing windows or upgrading your HVAC system, it is more complicated than that and those are both expensive options. Start with something simple like air sealing to reduce the wasted energy through walls, floors, and ceilings. To do this you need a blower door test to be performed on your home. A blower door test is a measurement of how airtight your house is.


Basically, an energy auditor places a BIG fan in the frame of one of the exterior doors on your house. The fan sucks air out of your house, lowering the air pressure inside the house. This will make “fresh” air try to infiltrate your house wherever there is a leak. This is the fresh air that comes in when your forced air heating and cooling system is blowing. The air coming from the unconditioned spaces of your home.

You can get two types of information with a blower door test:

  • How quickly air leaks into your house (a measure of your homes tightness), and
  • Where the leaks are (by using a smoke pencil to trace airflows or an infrared camera).

The results of this test will give you a list of places where you can improve your home’s energy efficiency and comfort. Then you can decide which options you can afford to change and which you need to wait to address.

This test will also help inform you, through the auditors knowledge and his use of an infrared camera, where you should add insulation and how much more you will need. While opinions will vary on how much, there is a consensus that the average home needs MORE insulation. Just make sure to put it in the right places or you are just wasting your money.