This paper discusses the current activity ann, in particular, the current research efforts in the area of earth sheltered building design, construction, and acceptance in the U.S.
Interest in the use of earth sheltered buildings has expanded greatly in the past 6 years, and particularly in the last 2 years. Prior to 1973, there were only a few isolated earth sheltered houses and scattered commercial and institutional examples of underground buildings in the United States. These were mostly built for design aesthetics or environmental reasons. Since then the number of earth sheltered buildings and houses being built has increased very rapidly. Since earth sheltering is not yet a term that is universally understood, it would perhaps be well to further define the concept before embarking on a discussion of what research is currently underway in the field. In broad terms, earth sheltering uses the earth as a barrier and a moderator.
The earth Moderates temperature extremes in the air, and moderates surface vibrations and airborne noise. It acts as a barrier to storm and wind effects, ultraviolet degradation, and an undesirable visual environment. It has a large thermal mass that can work well with an intermittent energy supply such as solar energy. The earth is also a natural element which supports vegetation and, hence, the other life processes on which we ultimately depend. Using the earth to shelter a house or building, then, is a means of providing a natural barrier to many undesirable climatic and man-made features of a particular area. The impact of the building on the surrounding environment will also be lessened, allowing more of the land's surface to remain in a natural state. Furthermore, and of particular importance at the present time, earth sheltering serves as a massive means of decreasing the dependence of the building on artificial methods of climate control derived from fossil fuel energy. Naturally, there are also some disadvantages to earth sheltered structures.
These relate primarily to the heavier and stronger structure required, tile need for high quality waterproofing and insulation to combat exposure to ground moisture, and the need for a higher level of design and supervision in small scale construction. Although earth sheltered designs are not limited to any fixed definitions, it will perhaps be helpful to explain two of the basic layouts that are typical of earth sheltered construction. A typical design that is very appropriate for colder climates is the elevational design in which windows and openings are grouped on one side of the structure, with the remaining three sides and roof earth-covered. When the windows do face south, a maximum amount of passive solar heating can be achieved to combine with the low energy requirements of the structure. A courtyard or atrium design is quite common and is a very appropriate design for a flat site or a warm climate. The courtyard does not have to be totally enclosed. Using a U-shaped courtyard allows an easier transition and visual connection to the surrounding ground.
