I was thinking along the same lines with the upgrade to A9, with the changes to the walls an insulated variant is especially important. Going into the specifics of a materials temperature characteristics I think is a bit too over complicated and should be avoided. I think a system of using the current materials they could add in a new wall sub series where a wall of any material would require 5 construction materials + 1 cotton cloth = insulated wall, of course since the wall is internally hollow to allow for insulation the walls durability would have to be slightly reduced. An insulated wall could also still carry a power cable just like in real homes.
I would like to point out that personally I think this is the wrong path with heating and cooling and I believe looking at the mod "Centralised Heating" gives the best solution with the introduction of vents. In any age vents and ducting have been the means to heat and cool houses and buildings, after all temperature transition through walls is generally considered as insignificant (unless you build one with supper conductivity like steel).
I would like to point out that personally I think this is the wrong path with heating and cooling and I believe looking at the mod "Centralised Heating" gives the best solution with the introduction of vents. In any age vents and ducting have been the means to heat and cool houses and buildings, after all temperature transition through walls is generally considered as insignificant (unless you build one with supper conductivity like steel).