i have walls insulated according to california build code. it's not really possible to add more insulation to them, unless you rip them off and do spray in insulation. insulated attic with radiant barrier and insulated floors.
i just checked with IR camera, most of surfaces in the house are now 22C-24C. After a few days of 40+C walls ill go to 25-26. some walls (south side of house) even higher. There are few little spots where insulation doesn't sit properly - it will be around 28C.
The biggest offender is skylight. Temperature near top of it can get to 60C.
Edit. I think most people simply do not realize what temperature have internal and external walls in houses and how it interacts (or counteracts) AC. If you will go to read greenbuildings/passive houses forums, there are a bunch of discussions about thermal mass of the walls
Do you have any actual numbers for what is up to code insulation in California? California is a very temperate climate. I wouldn't exactly expect their code to have the highest insulation requirements.
Also, building codes should be considered the minimum.
I am keenly aware of how much thermal mass walls hold. My apartment is 3 external walls that are constructed pretty much only of a few inches of concrete, bare. The result is that after a full day of summer sun, even though it drops to 64 degrees outside at night, my air conditioner cannot keep it 76 degrees or lower inside. It's crazy. It's worse in the winter when I can feel the walls sucking heat out of my apartment.
>Do you have any actual numbers for what is up to code insulation in California? California is a very temperate climate. I wouldn't exactly expect their code to have the highest insulation requirements.
R-15 for 2x4 or R-21 for 2x6. Not highest numbers in USA I guess and after you buy house that already "exists", it's expensive to change it.
>I am keenly aware of how much thermal mass walls hold. My apartment is 3 external walls that are constructed pretty much only of a few inches of concrete, bare. The result is that after a full day of summer sun, even though it drops to 64 degrees outside at night, my air conditioner cannot keep it 76 degrees or lower inside. It's crazy. It's worse in the winter when I can feel the walls sucking heat out of my apartment.
Whole house fan is the way to go. If you can't install one, I think a couple of strategically placed window fans over night to create some air flow through the house might work better than AC
I did some research on preventing walls from getting too hot (my room wall on the outside hits 170F i think). Narrowed it to
- Transparent paint with some particles that reflect
sun/reduce heat gain
2x4 walls are allowed at all? That surprises me, up in the north they haven't been legal for decades now. Well it is more you can't meet the rvalue with them, but still even cheap houses don't get them
Nope. It's west facing stucco wall without shadow. It's on sun through most of the day. With IR camera i clocked it in range of 65C-75C multiple times (so it's maybe not 170, but 165. hate C<>F conversions in head) . I had inverter on this wall, and it simply died from overheating.
Same wall on the inside get's to 30C or more if I don't run AC that blows on it. Wall is triple layer stucco over plywood, R13 fiberglass and then drywall.
it's not really possible to add more insulation to them, unless you rip them off and do spray in insulation.
Actually, it's possible to inject foam insulation into walls without ripping them off. It goes in through small holes, or through utility boxes. Plenty of companies do that. I've even seen it advertised on TV in California.
But injectable foam insulation usually going into empty walls. I already have butted fiberglass in there. I don't think it's viable to make laparoscopic wall surgery to remove fiberglass . I did a quick google, and looks like you can do injectable foam over fiberglass. But I am not sure how much R it will add, but I am sure that for cost of of injectable foam + wall repair, I can get another hvac and run it for next 10 years...
I did consider recently to double walls on sunny side of the house with few layers of foil backed foam boards.
Edit. I think most people simply do not realize what temperature have internal and external walls in houses and how it interacts (or counteracts) AC. If you will go to read greenbuildings/passive houses forums, there are a bunch of discussions about thermal mass of the walls