All around the world we have materials used for construction, but not all materials are available everywhere. Shipping materials over long distances requires enormous amounts of energy. This is not sustainable. In order for everyone to have access to housing, the buildings need to use materials that can be found all over the world, while still being able to maintain a low energy impact on the planet. One answer is the construction material found in every Earthship: used tires. In any country in the world there is a glut of used automobile tires, usually clogging up landfills or the ocean. In Earthships, these tires form the basis of the foundation.
To use these tires requires little to no energy, because it is already in a form ready to use. All building materials used for Earthship structures use little to no energy to manufacture into use. This allows Earthships to be easily accessible to everyone. Even a large scale production would still have a low impact against the planet.