Circulating water through underground pipes eliminates the threat of contamination from molds. The water can be used to cool thermal mass in the house or as the cooling source for an air handler system. An earth tube system is typically not competitive with mechanical air conditioning on solely an economic basis. 2.0 Direct System 2.1 Description Direct systems utilize conduction through building elements as the regulator of the indoor temperature. Generally speaking the largest climatic advantage of this system is in helping cool the living space.
Buildings can be earth-covered in varying degrees.
If the structure is built on the surface grade and earth is added around it, it is considered a bermed structure. Buildings can be constructed below grade or into hillsides and be totally or partially covered by earth. It is generally considered that earth-sheltered structures in this region are of marginal benefit to the operating energy costs of a building. It must be recognized that practically all earth sheltered homes are designed with passive solar principles. From the standpoint of the quality of the energy source, earth-sheltering and solar energy can be considered superior to fossil fuels.