High efficiency houses are actually constructed this way, although the gap is not "man-sized". It eliminates a large amount of thermal bridging. If it's worth

High efficiency houses are actually constructed this way, although the gap is not "man-sized". It eliminates a large amount of thermal bridging. If it's worth it to the owner, exterior walls will be framed with 2x6 instead of 2x4 to allow more space for insulation.