i would suggest you look into rammed earth homes.
there are a few different ways to build them. you can either make rammed earth bricks and build with those (like adobe) or you can form walls, and compact the earth directly into the form/wall. i prefer the formed walls, as it is easier to mechanize. (most natural homes use free/cheap labor, if you arent planning to do this, you better figure a way to mechanize, imo of course)
when we were looking to build a energy independent house, i was looking into the best way to mechanize a natural home similar to an earthship. (passive solar, thermal mass home)
rammed earth was the best compromise i could find. the walls are built our of road base type material, mixed with cement/portland to stabilize.
we found a local home build this way, and talked to the owners.
they used a skidsteer to dump the roadbase/cement mix into the wall form, then came back with a whacker and compacted it down. the guy mentioned with 2 high school laborers, we has able to put up ~ 30 ft of wall a day. Once the walls are up, the forms are taken off and the wall remains.
the walls are 18in thick so the temp inside stays pretty stable. south facing windows help capture heat and the floor walls hold/release that heat at night. a wood stove will go a long way in these types of houses.
the couple we met also had a 2100w PV array and told me they produced more power then they used over a 12 month period.
im probably not very good at explaining it, so here is a gallery of what im referring to:
http://www.rammedearthhomes.com/gallery.htm
also here is a book that explains more about it, and should be available at most libraries:
http://www.amazon.com/Rammed-Earth-House-Revised/dp/1933392371