Michael Reynold's website www.earthship.com is the best place to start. However, there is lots of material on line as this type of building modality is taking off. He also produced a film called 'Garbage Warrior' which I believe is still on youtube. Our building, when complete, will be 2200 square feet. Too big for just the two of us, but when full of kids, it did well. We used about 750 tires and they can be collected for free. However, we paid $150 a ton for them when we started in 2007. We used earth from the build site to fill them. The thermal mass is the earth in the tires, the earth behind the tires (6 feet) and the whole floor. I calculated for our build we have about 2 million pounds of earth regulating the temperature of about 800 lbs of air.