So you’re going to build an already-small superinsulated “pretty good house” (look it up). And you’re thinking of doing double-stud walls. Just remember that the extra 6″ or so adds up. It’s on both sides of the house, so it reduces the usable space by 1 foot in each dimension — x and y.
Let’s say you are building a boring rectangle that is 24×32 (inside dimensions). Well, that’s a 768 sqft. If you had instead built 25×33 (with single stud walls) then that is 825 sqft interior. In other words, you are giving up 57 square feet with your insulation. And that’s 7% of 825. So your house is now 7% smaller!!! Just be aware.
Instead you could do:
1) larsen truss
2) 4″ of polyiso added to the outside.
These are probably both harder than double-stud walls, I am just commenting that you should compare apples-to-apples — same interior square feet — when comparing options for how to build.
Article title could read… if everyone lived in an ecovillage and DIDN’T FLY… (old news that flying wrecks one’s footprint score since it makes it so easy to go so far….) https://theconversation.com/if-everyone-lived-in-an-ecovillage-the-earth-would-still-be-in-trouble-43905
GOLDSTEIN: John is not rich and he is not getting solar panels to save the world.
Does the environmental part of it – is that meaningful to you? Does that matter?
O’HAGAN: Not really. (Laughter).
GOLDSTEIN: If you were an environmentalist or if you just like solar power, John O’Hagan is your dream come true. John O’Hagan is the revolution you’ve been waiting for. He’s – he is not getting solar power for a moral or philosophical reason. He’s not doing it ’cause he’s worried about climate change. John O’Hagan is getting solar power because it’s cheap.
Actually, NStar (now Eversource) tells me some interesting things on my gas bill.
It tells me:
– avg therms per day
– avg temp over the billing period.
So for the most recent bill it was 5.1 therms/day and 19F avg
Last bill: 4.0 therms/day and 29F avg.
Does it make sense? Yes! If we make the assumptions that:
1) 99% of our gas use is for heating and not
– hot water heater
– stove and oven
– clothes dryer (gas)
2) An average inside temp over the course of day and night is roughly 65F
DeltaT= 65F-19F=46F with 5.1 therms per day
DeltaT= 65F-29F=36F with 4.0 therms per day
46/36 = 1.28
5.1/4.0 = 1.28
Or another way:
46/5.1 == 36/4.0 => 9.0 dT for each 1 therm
The ratios are the same! This is a little too good to be true. Probably some luck in my assumptions and guess of 65F. But in any case, that’s roughly what you would expect.
So IOW, if you want to keep your gas bill constant when it gets much colder outside, just keep it colder inside by an equal amount (to keep your deltaT constant) and you should do ok!
The only problem with this (besides not being able to wear more sweaters and hats at some point) is that you should be careful (if your house is like mine and colder in some spots) that you don’t cause some pipes to freeze in that already cold bathroom. Unlikely for most houses, but possible.
To truly tell which winters have been the worst, I propose a variation on the HDD (heating degree days… along with cooling degree days, great tools for comparing climates) calculation of “snow depth days” that also includes a multiplier of air temp (or maybe even adjusted for wind chill). http://www.wermenh.com/sdd/ne-1415.html
Or maybe the temperature should be an inverse of some sort, so good winters would be lots of snow, but also somehow mild temps.
Factoring in the amount of sun would be good too!