Dan, there are(were) two such houses like that here. I think they call them earth sheltered. Mostly concrete structure, built right into a hillside, which we have a lot of in this area! I think planning one so it didn't feel like a mole hole would be the trick, but they remain an even temperature due to not being very exposed to the vagaries of changing outside weather.
Probably 20 years ago when we were looking for property our realtor took us to a place where someone had started to build one of these earth sheltered homes and then abandonned the project part way through. Some problem with the weight of back filled earth and improprerly mixed concrete as well as a waterproof membrane that turned out to not be waterproof....for once we did the smart thing and said no thanks. Again, NOT a building method one should embark on unless you have an idea how much weight you will be adding when you bulldoze backfill over your roof structure! But they are a very low profile looking house, depending how they are situated.
Damn it! Now I want to build something! Oh, Rosewood is correct. Here in BC the building code allows for 24 inch on centre studs. Our scissor trusses are 24 inch on centre, despite our concerns. We were assured by the truss company that it would beef up nothing but our bill to go 16 inch. They are designed to carry our snowload at 24", and that's what is up there. But it's further stabilized with over 1500 sq ft of pine nailed to the bottom side. Oh..no air nailer. Each board installed by hand and the finishing nails tapped in with a nail set while Hubby teetered on the step ladder, yes, the top step!. Hubby complained about not having the right tools for the job. Such a whiner.