CHRISTOPHER MOLNAR, LLC
BABSON PARK, FLORIDA

A Blower Door Test is designed to test the tightness of the house. We are looking to find out how much air is leaking into and out of the conditioned spaces of the structure. The greater the leakage, the more conditioned (cooled and heated) air will flow through cracks, crevices, and other openings in the walls and ceilings, thus raising the energy bills and also decreasing indoor air quality. More about that in a minute. Florida energy code says that new and retrofitted construction must be tested by an independent third party and must be within 3-7 air changes an hour. By air changes per hour we mean how many times per hour 100% of the indoor air will be replaced with the outside air. The greater the temperature difference between the inside and the outside the faster the air will flow naturally. The first test I normally do is the blower door test. The reason I do this test first is that it gives me an idea of the overall tightness of the building and from there I can determine what I am looking at with the duct testing that comes second. After making sure all windows and doors in the house were closed I setup my test equipment and ran the automated test sequence that tests the leakage at different pressures to come up with a true leakage rate. In this case the house was leaking within legal requirements for new construction at 5.08 air changes per hour. What this means is that 100% of the indoor conditioned air is being replaced by outdoor air about every 12 minutes. Think about that for a minute. All of your conditioned air, the air that you have paid to heat, cool, dehumidify is being replaced by unconditioned air every 12 minutes. More if the wind is blowing and causing greater pressure differentials between inside and outside.