During a blower door test we use pressure to determine how much air flow enters the building during a given time. The 2009 IECC, 2012 IECC, 2018 IECC, and all energy star homes are required to have a blower door test. It informs us if the home will performed as it is modeled to perform. A home that is too leaky does not allow any control on the structure, air infiltrates and exfiltrates wherever it can. This creates drafts, high energy cost, allows pest to enter the structure, moisture issues, and the home will not perform as it is designed to perform, which can cause issues with the HVAC systems. For home owners we highly recommend a blower door test for anyone wanting to improve the efficiency of their home and we include this test in all our audits. We also highly recommend this test if you are building a new home, especially if spray foam is used.
All builders should be actively using a company that provides blower door testing. We highly recommend that all builders contact TPI so we can start testing and advising you on what to expect for the new codes. Some cities have already adopted blower door testing for code compliance, and many other are soon to follow.
Homes are under constant pressure differentials which will suck air into the home or blow air out of a home, which means you are constantly loosing your heated or cooled air. Homes create a natural effect called a stack effect, leaky homes create a stronger stack effect than tight homes. We always recommend making the home as tight as possible and controlling where new air is introduced into the home. Controlling air flow is not just energy efficient but also healthy for the home; it helps control moisture intrusion, high humidity, low humidity, dust, pollen, mold, and prevents rodents and pest from getting in the home. The picture below illustrates what the stack effect does.