As stated previously an earth sheltered house uses earth as a form of insulation, primarily to reduce temperature fluctuations inside the house and reduce energy consumption. 'Earth sheltered' is a fairly loose term used to refer to a building which does this to any reasonably significant degree. This includes houses such as the following:
An earth-bermed house qualifies as 'Earth sheltered'
This diagram shows a section through what is in effect a conventional house with earth 'bermed' against the walls. It is not incorrect to refer to this house as 'earth sheltered', however it is more accurate to refer to it as an 'earth bermed' house. The other basic type of earth sheltered house has its roof covered to some extent with earth, this type can be more accurately described as 'earth covered'.
Just as there are two basic types of 'earth sheltered' house, there are also many variations on these two basic types, the rest of this document and indeed the entire web-site will deal more specifically with 'earth covered' housing. This is because of the increased energy efficiency of 'earth covered' buildings over 'earth bermed' buildings. Much of this material is still relevant to 'earth bermed' housing although usually to a lesser degree.
The following section defining the different types of earth covered houses is adapted from Baggs et al., pp17-19.
Earth covered buildings can be separated into the following basic types:
Types A1, A2, A3 and A4
These all have their floors located at ground level, or above the ground at the lowest entrance point or door. Because these type A buildings are not recessed into the earth where temperatures are more stable they are potentially less energy-efficient than type B. This type of construction is used when excavation should be kept to a minimum because of rock, or where a watertable exists near the ground surface. Should extra rooms be needed in the future, type A buildings are more easily adapted than type B buildings.
A1 Chamber:
This type of house has an earth-covered roof and berms around all its sides with no windows. Although such a house would have quite good insulation properties, the conditions inside would be unlikely to please most people, ie. no natural night.
A2 Atrium:
In Roman times, urban dwellings in particular gained privacy by having their open space located centrally in relation to the house as a courtyard (atrium) surrounded by rooms. Consequently, the atrium-type earth-covered building has the spatial characteristics of the Roman atrium house (combined with those of the A1 chamber type.)
A3 Elevational:
This is similar to a chamber-type earth-covered building except that it has one wall exposed. This wall has windows, probably to a view, and preferably to the sun for passive-solar purposes for which this type is ideal. Side walls may have small areas of windows with earth-berms up to sill level.
A4 Penetrational:
This type of building has windows to more than one elevation of the building. Of all the types of earth-covered buildings, this is the least energy-efficient unless special provisions such as double glazing to doors and windows, or shutters, are used to conserve thermal energy. However, if windows are used all around, the internal rooms would not need any skylights, and future extensions would be easier than for other types. This type has good potential for catching cool breezes in summer. Out of all the types of earth-covered building this is the closest to a conventional house.
Types B1, B2, B3 and B4
All these types have their floor levels below the ground surface level at the lowest entrance point or door of the building. Hence, cool air will 'pool' at floor level to a height equal to the height of the steps necessary for access from floor level up to the door threshold.
B1 Basement Chamber:
This term is used to describe a building completely enclosed by earth, except for the entrance/exit. It is the type used for cyclone or tornado shelters. If correctly designed, it is suitable for nuclear blast and fallout shelters. For various reasons, complete shopping complexes have been built totally underground (e.g. Japan, Paris and Montreal). Elsewhere in the world, this type is used for transit networks, defence complexes and explosives stores. (Again, Not very pleasant to live in.)
B2 Recessed Court:
As explained, the Roman atrium house contained an internal courtyard surrounded by rooms. In an atrium house (described as 'recessed court' to distinguish it from type A2) one can stand in the atrium and not be conscious that the house is below ground level. One normally enters through the atrium, although direct access into the house is possible. While sometimes awkward to plan, this type is highly energy efficient due to the large amount of earth insulation and minimal door and wall openings to the atrium. In very cold climates, the atrium can be covered, while still permitting the entry of light into the rooms off the atrium.
B3 Wall Exposed:
This type is totally buried beneath earth from the front of the roof to its back edge. The front is usually the longest edge of the roof. The rear wall is fully earth insulated and often so are the side walls. This type with an elongated rectangular plan, can balance good insulation of three walls, floor and roof with an exposed front wall. This provides all front rooms with a view, and approaches the appearance of a conventional home. However, solar gain and thermal losses all need careful design consideration when complete wall areas are exposed.
B4 Recessed Penetrational
This type of building, constructed in a previously prepared excavation, has windows and/or doors to the back and front elevations. This type represents only a slight increase in energy efficiency over type A4 and is thus potentially one of the least energy efficient possibilities.
Last Updated: 2001-09-23