From what I’ve studied, fully underground housing is more
expensive because of extra engineering requirements and
excavation expenses and possibly materials. According to one
study I read, if you have 6″ of concrete on top of house,
plus 8″ of styrofoam a few inches of small gravel and 6″ of soil, this is equivalent to 20′ of earth.
at https://www.larrydgray.net in my recommended books section I list
some underground house books that I have read.
at my blog https://blog.larrydgray.net I have an article on
green building and one on earthen construction. Both of those
should be interesting for you to read.
I am more in favor of above grade house, with berms on 3 sides
and earthen roof with heavy insulation and 6 to 8″ of earth and
sod.
Rob Roy has a some good books along these lines.
