First, I want to say that there is so much information to go through on earthships that you really should check out the website: http://earthship.com/. I will try to give you a simple explanation, but I’m sure I will leave things out. Earthships are homes that are entirely self sufficient. They grow food, run off solar or wind, collect their own water, treat sewage, and heat and cool themselves. I know I’m making the house seem like it is a living being and it isn’t, but it is kind of like its own little eco system.
Again, this is hugely simplified and I am simply relaying information that I have read. You build the outer walls out of old tires. You fill them with dirt and pack them tight, then bury the back of the house underground. The tires are structural and provide thermal mass. The sun will warm the thermal mass and then slowly release the heat back into the house overnight to keep the temperature fairly stable. The front face of the house is a greenhouse. The windows are angled so the winter sun is let in and the summer sun is minimized. The plants growing in the greenhouse are treating the grey water the house produces to help them grow. The water from the shower etc. runs through the planter and comes out cleaner on the other end. This water is reused to flush the toilet, then goes to a leach field. A septic system is not needed, although it is sometimes used to keep to code. The roof is used to collect rainwater to provide all the water needed to supply the house. Since the water is used and recycled, you need much less water. The house has a filtration system for the water so that you can get you drinking water this way too. Any electricity you need is provided by wind or solar. So that is it in a nutshell.
According to the website, you can build these houses very inexpensively if you do everything yourself. It seemed to be a little to complicated for us, so we figured we could hire the crew to help us build. That would increase the cost quite a bit though. The we thought about just buying construction plans and figuring it out. However, for the size house we want, the plans were $10,000 or more. At this point, the purpose of building cheaply so that I can retire VERY young is destroyed. The systems for the earthship can also be purchased from the crew, but I did not price that.
I am very torn about this particular house. It would be a fantastic house to live in. I’m not sure the cost will fit in with our plans, however. And as I said before, it may be just a little bit too technical for our very limited construction skills. Still, a very good option.