I've been looking into Earthships recently. It seems that they would be great homes overall. You might want to look into it more yourself.
Earthships are earth-sheltered autonomous buildings made of tires rammed with earth, which are usually arranged in "U" or horseshoe shaped modules. Each tire is rammed full of earth manually using a sledge hammer. Windows on the sunny side admit light and heat. The open end of the "U" shaped structure faces South in the northern hemisphere, and North in the southern hemisphere, so that the house will catch maximum sunlight in the colder months. An Earthship is designed to interface with its environment wherever possible and create its own utilities.
Internal, non-load-bearing walls are often made of a "honey comb" of recycled cans separated by concrete. The walls are then usually thickly plastered, using the pull-tabs on the cans as a lath to hold the adobe and stucco. This is known as a tin can wall.
The roof of an Earthship is heavily insulated.
Some links to check out to find out more about Earthships:
* Earthship Wikipedia
* Earthship from start to finish
* "Our Earthship" a site with lots of pictures and information