> The us doesn't use concrete for residential walls (very often) but that is actually quite good from an insulation perspective That is an incredibly incorrect

> The us doesn't use concrete for residential walls (very often) but that is actually quite good from an insulation perspective That is an incredibly incorrect set of statements. The insulation value of concrete, it's R=0.52 per inch of thickness. A vast amount of housing in many regions across the world is concrete (including the walls). Obviously, it is more common in multifamily construction and/or hurricane prone areas. Hollow wood framed walls w/o insulation depends on the relative humidity, but it's R<2. Fiberglass batt (R-12 and higher) is basically the only source of insulation in a wood sheathed wall.