How Much Does a House Lose by Air Leakage

I had the privilege of teaching a Building Science lab at Humber College last year and the innovative things these students did even in light of a bleak job market impressed me. I received an email recently from one of the graduates, David Dokhoian, who sent me his energy modeling calculations to express the impact of air leakage on an average home. David’s graph says it all:

David's Calculations II

David Dokhoian’s done the number crunching on air-leakage for a typical new Ontario home. Yes, its true the energy losses are low through the envelope, but its readily apparent that taking care to air seal the house has significant energy and durability benefits.

Curiously, the Ontario Building Code doesn’t require any minimum air leakage or a simple quick test, which is just leaving money on the table. We’ve tested new townhomes (attached on both sides, should be air tight) and can be upwards of 6 Air Changes per Hour.  We get told often that we’re splitting hairs by making homes so air tight, but we respond two fold:

  1. If installing an HRV or ERV in the house, you should make that mechanical investment earn its keep. We do that by making the home more air tight, ideally less than 2 Air Changes per Hour. Installing an HRV in a leaky house costing the home owner more money and is borderline belligerent.
  2. Homes with high R-value enclosures that are indiscriminately air leaky are just begging for a recall and an eventual moisture related issue.

Don’t be sloppy, seal it up and ventilate the house mechanically!

Finally, a big thanks to David for crunching the numbers! Thanks for all your help on the double brick study too!


David Dokoian’s LinkedIn contact: