There are many options for natural insulation, rather than the frankly ridiculous fiberglass-based toxic terror.
- 7 eco-friendly insulation alternatives for a green home
- Denim Insulation
- Shear innovation: How sheep wool insulation is keeping Mongolians warm
- Bellwether Materials' SoftBatt Wool Building Insulation
The lanolin and dirt has to be removed from the wool, otherwise it will rot and stink. Wash it at about 51c with a biodetergent, but don't do it in your own washing machine because it will gum it up. Spread it out in your yard to air dry. It's a good idea to treat the wool with a dessicant. In the US, green pest treatment for wood can be bought at any hardware store and used on the wool. Best not to use poison. Little creatures will find the pure washed wool very comfortable but the dessicant will make them uncomfortable but not necessarily kill them. They will move out to a more accommodating lcation. When it's dry it's ready to go.... I'd guess a foot thick would keep you warm when it's cold and cool when it's hot.