An earth-sheltered home is protected from the elements and requires little maintenance. It can outlast a conventional home by decades.
The earth-sheltered home is constructed to take advantage of the earth’s immense thermal mass, it will stay warm in the winter and cool in the summer without demanding significant inputs from energy-consuming auxiliary heating and cooling systems.
Also, because it is so very well-sheltered by the warm embrace of the surrounding earth, an earth-sheltered home will be very protective to the dangers of natural disasters such as tornadoes, hurricanes, earthquakes, and wild fires (and human intruders with bad intentions).
An earth-sheltered home is an exciting option for all who are willing to search for a more efficient way of living.
While some earth-sheltered homes are built completely beneath ground level, many are constructed using a technique known as berming.
Earth-bermed homes are built largely above ground, but piles of soil are then pushed up against the walls – all the way to the top – to form a protective cocoon of earth and vegetation that will separate the outer shell of the home from the open air.
Roof covers of soil and vegetation may or may not be included with earth-bermed homes, but most seem to prefer them since they do increase a house’s protection against atmospheric heat and cold.
There are three primary design styles for earth-sheltered homes: atrium, penetrational, and elevational. For those who would like to maximize their protection from the sun, the wind, the heat, and the cold, the atrium style is definitely the way to go.
All of the rooms in such a residence are built completely beneath the surface of the earth, in a “town square” type of arrangement surrounding a central atrium space that functions as the home’s entrance from above ground.
Each of the rooms of the home will face the atrium on the north, south, east, or west, with spacious windows and possibly glass doors to allow the natural light to filter in from above.
A short flight of stairs down into the atrium is all that is necessary to reach the bottom of the home’s central space, as the underground rooms are generally placed no more than three feet beneath the earth’s surface, given that subterranean temperatures are steady beyond this point.
Because its open outdoor space and adjacent rooms and entrances are all below ground, the atrium style delivers the most privacy and the greatest amount of protection from the vagaries of nature (high winds, thunder storms, tornadoes, hurricanes, wildfires, etc.).
However, because it is literally a hole in the ground, the atrium can easily fill with snow in a blizzard or rainwater in a tempest, which can cause flooding and drainage problems if some kind of system for diverting rain or melting snow has not been installed.
Because the living areas are entirely beneath ground level, the rays of the sun are not able to enter at a low enough angle to provide ample amounts of natural light, and because the central outdoor space opens directly to the empty sky, the views enjoyed from inside the home are only as good as the effort that has gone into creating an attractive atrium space.
The elevational style, strictly speaking, is neither underground nor bermed, but is more of a combination of both. Elevational homes are built directly into hillsides or mountainsides, looking almost as if they have been inserted into the mouth of a cave, to enough depth to completely cover the side and back walls of the home.
The front of the house is left open to the air, usually facing the south in order to harvest the natural heat and light provided by the daily sun.
Roof covers are normally added to such a home to complement the berm-like sheltering effect of the hillside, and houses constructed in the elevational style have shallow rectangular shapes that feature bedrooms and living spaces arranged linearly in the foreground so the sun can provide heat and light to all the important rooms of the house.
Elevational homes are the least expensive type of earth-sheltered structure to construct, and with their hillside locations they frequently offer grand panoramic views of surrounding natural vistas.
Penetrational homes are built above ground, but are designed to fully exploit the protective abilities of the earth. Each wall of a home constructed in the penetrational style is completely bermed, with only the spaces over doors and windows left open to facilitate easy entrance, good cross-ventilation, and the effective harvesting of natural light.
Roof covers are the perfect finishing touches for such a home, which is so well protected from the elements that it might as well be completely under the ground, even though the entrance of light and air remains unobstructed.
Variations on the penetrational approach are certainly possible; for example, the southern side could be left open as it is in an elevational home, while the rest of the house (save for the windows and the back door of course) would be fully bermed.
Problems And Issues
Inside the protective shell of the earth, temperatures generally remain between forty-five and sixty-five degrees Fahrenheit all year round, and it is this moderate range that allows underground homes to remain comfortable in all seasons.
Because the surrounding temperatures are so mild, heating and cooling costs can be reduced from 50 to 70 percent in an earth-sheltered residence.
However, this will require the use of insulation, since unprotected walls will eventually reach thermal equilibrium with the surrounding earth unless steps are taken to ensure that heat produced or collected inside the home is not leached away through the walls.
The value of the earth as a climate modifier does not come from its insulating properties, which are minimal, but rather from its capacity to soak up and hold warmth, allowing it to maintain a moderate temperature level and dramatically reduce the need for artificial heat or air conditioning in an earth-sheltered home.