A few weeks ago we ran our first blower door test at our Passive House in Columbia City, with results indicating we had to look for leaks and holes to patch and come back and redo the test. Our first test, resulting in a reading of 1.62 ACH50, meant that there were 1.62 air changes per hour (or ACH) under 50 pascals of pressure. A pascal, by the way, is a unit of pressure measurement which is used more commonly now–rather than “pounds per square inch”.
In order to qualify as a Passive House the house must meet a standard of passing the blower door test of a .6 ACH at 50 Pa. That means when under pressure of 50 pascals, the home must have only .6 air changes per hour, or better. Well today we ran our follow up blower door test and acheived a .58 ACH50! Measures that were taken to bring us to success included re-installing windows, reapplying the exterior waterproof sealant, and taping or sealing tiny holes where joints meet.
You might be wondering how these numbers translate to real life. So for starters, the fewer air changes that happen in your home the better as this means you are not loosing air you’ve heated or cooled. A regular code home changes air about 7 x per hour under 50 pascals of pressure. An Energy Star home, depending upon your climate, allows for 5 or 6 ACH. So, with a a 0.6 ACH, Passive Homes are ten times more tightly sealed than the standard applied by Energy Star! Our 3rd-party verifier Tadashi Shiga notes that Passive House is 90% efficient or 90% better than a code built home, so its like getting a 90% discount coupon on your monthly space heating and cooling bill! Less air infiltration makes the home more sustainable, as there is less degradation, and the ultimate translation for all of this is seen in your very low heating or electric bill! For example, 2,000 square foot Passive Home mustn’t use more than 2,800 kwh for space heating a year but according to the U.S. Energy Information Administration, the average U.S. home uses the equivalent of 11,800 kwh for space heating. Do the math and you will see why Passive Home is the true house of the immediate future.
We’ve begun shooting video about our Passive House project – click here for Part 1 (this clip is earlier the same day of our test, before we got to our numbers) and subscribe to our Youtube Channel so you don’t miss new videos in the series!