I have designed and built about a dozen solar and or super or well insulated homes.

In the real peak of it I insulated a number on the outside by putting 1.5" of blue styrofoam outside the concrete. We put metal over the exposed portions of the styrofoam to protect it from ultra violet light.

It is ideal from an energy performance standpoint but one of the homes got termites up under the styrofoam and into that part of the house.

After that I quit insulating on the outside.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.