In addition they usually have their own natural ventilation system. Earthship homes are ‘off the grid’ minimizing their dependence on public utilities and fossil fuels. At present there are 3 off- grid communities, the largest comprising of 60 homes with plans for a further 130. All utilize available local and ‘green’ resources, especially energy from the sun; buildings are shaped to maximize the natural light and solar power during the winter months. Their roofs are heavily insulated – often with two layers of four inch poly-iso insulation – for energy efficiency.
Furthermore, Earthships even have contained sewage treatment and sustainable food production on site.
Cost for these eco-friendly homes range from about to several million dollars, depending on how big and lavish they might be.