Underground home
When a sheltered home is built underground it is referred to as an 'Underground Home' To be considered an underground home the dwelling must be at least 0.2 metres but some can be as much as 3 metres. The house is built completely below ground on a flat site, and the major living spaces surround a central outdoor courtyard. The windows and glass doors that are on the exposed walls facing the atrium provide light, solar heat, outside views, and access via a stairway from the ground level. Atrium/courtyard homes are usually covered with less than 3 feet (0.9 meters) of earth primarily because greater depths do not improve energy efficiency. This style also offers the potential for natural ventilation.