Definition: Earth sheltered, or underground, houses lie mostly beneath the ground surface. The surrounding soil provides natural insulation, making these houses inexpensive to heat and cool. The best location for an earth sheltered house is on a well-drained hillside. Windows facing the south or an overhead skylight will fill the interior with sunshine.
Designers of underground homes have developed several methods for regulating the interior temperature. Some underground homes depend entirely on the natural insulation provided by the walls and floors. Sometimes tubes are channeled through the earth to bring in air. And, sometimes a heat pump is used to regulate temperatures.
Earth sheltered homes are typically made of concrete. Construction costs can run 10% higher than that of a conventional house. However, enthusiasts say that the lower maintenance and energy costs make earth sheltered homes a good buy.
Earth sheltered homes are not suitable for permafrost regions.