Saturday, the 24th of January, 2026. It may well be the coldest day of the year, all of -14°F (-26°C). But the house is a toasty 68°F (20°C). Yesterday morning, though, the furnace couldn’t even hit the set point. What happened?
My guess? A little thing called air leakage!
The basic logic of physics– which, in turn, informs all energy retrofit logic- says that most heat losses are vertical, through the roof (or attic). This is because, as my old landlord in Iowa used to say, “heat does tend to rise.”
Heat itself, as it turns out, doesn’t tend to rise– it tends to transfer from an area of more thermal energy to an area of less thermal energy. But warm air rises. And especially in homes where the predominant heating mode is forced air, that means losses are that much more pronounced.
Attics are a big deal, certainly, so that’s why that’s usually the best place to start with adding insulation to an existing house.
But oft-overlooked is the fact that air leakage can account for as much as a third of building envelope energy losses. What’s even weirder is that this number seems to hold approximately consistent across both residential and commercial buildings.
I used a thermal camera and a pair of hands to identify air leaks around the built-in cabinets in our dining room, sealing them with a combination of rope caulk and, once I ran out of that, masking tape. The result? We went from a cool, drafty 62°F to a substantially less drafty 68°F, even as the temperature outside dropped another 10°F.
The room is substantially more comfortable. Will our bill still suck? Yes. Will it suck less? Yes.
DIY Or Hire Out?
Energy retrofits are rare in the United States in 2026 for a few reasons. The biggest reason is that there aren’t many folks who do it, no matter how much every handyman will nod and say, “yeah, yeah, yeah, I can do that!” (They may or may not be able to). Another reason is that, even if someone does have the skill, it’s difficult, thankless, unglamorous, and often tricky work. People are overworked as it is– no one wants to get paid a couple of bucks an hour to lie on their back in an attic, squinting at a spider-infested hole that may or may not be a good idea. (Confession: it’s me. I’ll be that guy).
Of course, energy prices spiking might be the incentive we need to start (re-start?) caring about energy efficiency and retrofits like we did in 2009, when oil and gas prices were through the roof. But I’m holding judgment on that one.
I know. Smooshing goo into a crack through which air is leaking? How hard can that be?
Well, it isn’t always entirely intuitive, is the problem. Sometimes it’s not clear where what is leaking air, or how much. I have commonly found myself spending time air sealing one area, only to find out that there’s another area somewhere else where leakage is much worse. That’s fine. Owning a house in a frigid winter climate generally sucks. The key is to think about what one can do to reduce bills.
Don’t be like Lawrence, my former colleague in Detroit, who once told me that in his old place, he was paying $700 a month in the winter to heat the place, and “I don’t think there was a single thing I could have done to make that place more energy-efficient.” There is always something.
Next up for us? In the spring, we’re going to investigate how awful it would be to remove all of our (wood shingle) siding and replace it with something else installed on rigid foam, installed on a continuous air barrier, installed on sheathing, installed on the original studs. I do not want to think about how expensive this is going to be, but it’ll be cheaper than paying hundreds of dollars a month to live in an icebox.