Have you considered inventing a time machine, going back in time, becoming a general contractor, and then building your house but smaller? Smh, people won't go the slightest bit out of their way to make things better these days.

Both Europe and US are big enough to have a huge variety in building codes for different climates in different states/countries.

Its not all about insulation though. A terrace has much less exterior wall than a row of spread out detached homes. Some still insulate the party wall. but more for sound reasons. But the main advantage of terraces , fossil fuel-wise, is that the medium-density is more likely to give you a walkable grocery + other stuff and a somewhat useful bus service or other public transport.

Though modern suburbs here can be pretty sparse too with more detached homes.