You forget a thing: cities are not made today from ground up, most of buildings are old construction with far less isolation and air tightness than individual h

You forget a thing: cities are not made today from ground up, most of buildings are old construction with far less isolation and air tightness than individual houses. Of course individual houses are not built all today but they are far frequently rebuild from ground up than bigger buildings resulting in a far superior median isolation. Evolvability matter and too many fail to take that into account. We do not live today, since and for today.