I have been reading about underground or "earth sheltered" houses online for the past couple days after watching all three lord of the rings movies in succession...
I have found lots of advantages to building underground:
-less materials (but lots of concrete)
-stable temperatures year round
-uses less energy to heat and cool
-blends in with landscape
-tornado resistant, fire resistant (built mainly of concrete)
-soundproof
The only disadvantage I've read about is controlling the humidity and moisture levels inside the home. A few sites I visited claimed this could be controlled by ventilation tubes going up to the surface.
roof contractors