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AlternativeWay4729 t1_j5je4c6 wrote

Our old farmhouse isn't that large, about 2000 feet with a recent extension, but it has distant wings, so doesn't heat easily.

When we got it, it wasn't insulated. The previous occupants used 700 gallons oil and ten cords of wood a year. We didn't exactly convert the place from oil. The oil furnace is still there. What we did was make incremental improvements. First we put in a wood stove and used that instead of the oil hot air furnace for about 80% of the heat. Then in stages we air sealed and insulated: new windows and doors, R40 cellulose blown in the attic, four inches cellulose blown into the stud bays, and two inches R10 foam board over the entire outside. Spray foam on the upper four feet of the cellar walls and joist bays. Smarter thermostats for the furnace and baseboards. Every year for five or six years we did something to improve on air sealing and insulation. We did it all ourselves.

Then we built an extension that had R10 foam board and six inches cellulose in the walls and R40 in the attic. We added a heat pump in the kitchen where we can feed both wings, although not well enough to get to the far corners where we have electric heaters to top up. We added solar, 2.7kW/hour of sunshine, which cancels out some of the extra power needed for the heat pump and baseboards. Right now we use 3-4 cords firewood, less than 50 gallons oil, and our power bills go from $40 in summer to $100 in late fall and spring to $300 in January and February. Quite a bit of that is tank heaters and heat lamps for livestock and block heaters for a tractor, though. We measured their consumption with a meter and it is high, as much as $80/month. If we didn't want to keep stock then we'd have only $120 to $180 more electrical consumption/month in winter. Our power bills would top out just over $200/month. I estimate our total actual heating costs at about $1200/year. Right now we are replacing the furnace with an identical newer used model. We don't use it much -- we've gone only from from 1/3 to 1/4 of a tank so far this year. But when it's really cold we do use it to keep the house warm when we're not here. It sits in the cellar so it keeps the pipes from freezing. The old one is getting rusty because the 120-year old cellar is damp and floods occasionally. And the insurance company wants us to have one, even if we barely use it.

(Full disclosure: I was an energy academic before retirement. Now I'm just a grumpy handyman.)

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Seyword t1_j5jlijf wrote

Sounds like a full time job.

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SeamusRomney t1_j5kp5yo wrote

Another retiree and grumpy handyman here, can confirm - it's a full-time job.

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AlternativeWay4729 t1_j5jej13 wrote

I should mention we cut some of the firewood ourselves, off our own land. But not all. About half.

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mcot2222 t1_j5kcv41 wrote

“R40 cellulose blown in the attic, four inches cellulose blown into the stud bays, and two inches R10 foam board over the entire outside.“

I’m curious about this. Do you mean the outside of the house? I’ve done a lot of insulating and air sealing but I think my fundemental problem is that my foundation is from 1961 and they never insulated foundations back then. I was thinking it was too big of a job to retrofit that.

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AlternativeWay4729 t1_j5kfdfp wrote

We first took off the bottom six to eight inches of siding and sheathing. We cleared out the mouse nests and other debris from the old stud bays. We scarfed in some new wood in a few places where there was partially rotten sill. Put PT sheathing over that. Drilled a two-inch hole at the top of each floor's stud bay. Blew in cellulose until it wouldn't blow in any more. This requires a special blower, not the one they rent at Home Despot. Put two-inch foam board over the old siding, glued at the edges. Put 7/16 OSB nailer over that with long screws. Then my wife put up shingles, which she likes to do. The house was built of rough cut hemlock, fully four inches, which at R3.8/inch for cellulose is about R15 for the stud bays, and the foam board makes it R25. But it's the air sealing that does most of the work. It was still drafty until a couple years later when we put spray foam over the top several feet of cellar wall and over the joist bays. It's not hard. We did it ourselves with the canisters they sell at Home Depot. You have to suit up and wear a very good respirator. It's recommended that you use the kind with an air supply. I didn't, and survived, but I should have done. But you can get a contractor to do it for you and they have all the proper kit.

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