An Earthship is a type of house that is built with natural and recycled materials with energy conservation in mind. Designed by the architect Michael Reynolds and his company "Earthship Biotecture", it is built to produce water and electricity for its own use. Mainly made of earth-filled tires it takes advantage of thermal mass, natural heat insulation and ventilation to maintain its temperature. Since it does not require any public utilities such as gas, electricity, water or sewage it can be considered as an off-the-grid housing, meaning that it can live away from public utilities.