Old houses, actually even many new houses, have air leaks. When we removed the wallpaper and exposed the shiplap, there were areas where you could see daylight through the walls. They didn’t insulate houses in 1907 and they also didn’t have any real concern about air sealing.
“Air Sealing” is a term that is used to plug all (or at least most) of the air leaks in a house. A huge amount of the energy inefficiency of a house is simply the heated air leaking out through cracks in the wall, floor, ceilings.
This became very clear to me a number of years ago while attending a conference in Portland, Oregon. A Portland architect was called to help a client who had purchase a vintage old house. They did the requisite replace the windows and blow insulation into the empty wall cavities. And they found no change in their utility bills.
No Change.
They did a blower door test (which measures the air leakage on a building) and found gaps everywhere. The air leaking out of these gaps rendered the windows and insulation virtually ineffective. At that time, they were foaming and caulking throughout the house. Time consuming and arduous.
Fast forward to today. We came upon a system called “Aero Barrier”. They were very reasonably priced, came out to the Onion House and it was all done in a day. Their system pressurizes the house, sprays an environmentally-friendly sealer that finds and seals the gaps. Check out their website with the link above. It’s fascinating process.
And effective.
As you can see from the photo, we went from 3,530 cubic feet per minute of leakage (about the volume of a two-car garage; every minute) to 138 cubic feet per minute, resulting in a reduction of 96%.
We did insulate and replace windows, but this one item was, in my opinion, the single most effective thing we did on the house. Our son’s utility bills are now very reasonable and we feel the savings will repay the cost to seal in maybe two years, if not less.