In fact, this Passive House was so tight, that we had to use a duct leakage fan to test the whole building rather than the normal large fan. And even with that smaller fan, readings didn't begin until the duct leakage fan was on the smaller Ring 2.
The home, dubbed the "Right-Sized Home" by the project team, is located in Oak Park, IL, and is a modest, but extremely well thought-out 1,660 square feet, 3 bed, 2.5 bath single-family house. The house is relatively unique to the area in that it is slab-on-grade construction (no basement).
Building science nerds are going to appreciate the measurements that we obtained:
Measured fan flow: 134 CFM @ 50 pa
Envelope volume leakage: 0.43 @ 50 pa
Envelope area leakage: 6 sq in
Below is the fan curve from the pressurization test.
Why is this so good? That 6 square inch hole is about the size of the bottom of my coffee mug, or the equivalent amount of draftiness as a 24" window cracked open just 1/4 inch. That means much better control of the indoor air quality.
What this means in the real world is probably best summarized by this metric:
Estimated cost of air leakage for heating: $ 11 per year for heating.
This is the tightest home that our team has ever tested, but we would like to throw out a challenge. Can you build one better? Let us know!
Check out this house for yourself July 25-26 on the GreenBuilt Home Tour.