earthshelter.com The Science of Earth Sheltering (source: Wikpedia.com) Thermal Mass: The earth's mass absorbs and retains heat. Overtime, this heat is released to surrounding areas, such as an earth shelter. Because of the high density of the earth, change in the earth's temperature occurs slowly. This is known as 'thermal lag.' Because of this principle, the earth provides a fairly constant temperature for the underground shelters, even when the outdoor temperature undergoes great fluctuation. In most of the United States, the average temperature of the earth once well below the frost line is around 55 to 57 degrees Fahrenheit. The depth of frost lines vary from region to region. In the USA frost lines can range from around 20" to 40+". Thus, at the base of a deep earth berm, the house is heated against an exterior temperature gradient of perhaps ten to fifteen degrees, instead of against a steeper temperature grade where air is on the outside of the wall instead of earth. In the summer, the temperature gradient actually helps to cool the house. Passive Solar: A south facing structure with the north, east, and west sides covered with earth, is the most effective application for passive solar systems. A large double glazed window, spanning most of the length of the south wall is critical for solar heat gain. It is helpful to accompany the window with insulated drapes to protect against heat loss at night. Also, during the summer months, providing an overhang, or some sort of shading device, is useful to block out excess solar gain. Combining solar heating with earth sheltering is referred to as "Annualized Geo-Solar Design", "Passive Annual Heat Storage", or sometimes as an "Umbrella House." Energy Consumption: As a result of the thermal mass of the structure, the thermal lag of the earth, the protection against unwanted air infiltration and the combined use of passive solar techniques, the need for extra heating and cooling is minimal. Therefore, there is a drastic reduction of energy consumption required for the home compared to homes of standard construction. "Earth sheltering." Wikipedia, The Free Encyclopedia. 16 Mar 2007, 12:16 UTC. Wikimedia Foundation, Inc. 16 Mar 2007 <http://en.wikipedia.org/w/index.php?title=Earth_sheltering&oldid=115538557>. Simply put, your home is being heated in the winter and cooled in the summer with energy that is free, abundant, renewable, and produces no pollution. No conventional home has this benefit! With a PBS, Inc. home, we guarantee you'll love living in partnership with the Earth! The High Cost of Inefficiency & the Solution: Americans spent over $95 billion to heat and cool buildings in the year 2000, consuming 13.3 quads (source) of energy in the process. A large fraction of this energy is lost through walls, roofs, and floors, and advances in building envelope technologies are key to reducing overall building energy consumption and costs." DOE (Dept. of Energy) By designing for the advantages of thermal mass and passive solar, our homes benefit from energy that is clean, abundant, reliable, and free. Our patented system received an Award of Energy Innovation from the DOE. "The key characteristic of an earth sheltered house from an energy standpoint is that the house itself is the energy system. Windows are the collectors, roof, walls, and floor are the storage; and earth is the protector and moderator. Little can go wrong in the functioning of such a simple system." Oak Ridge National Laboratory Earth sheltered buildings use less energy, cost less to operate, use fewer natural resources, and impact the environment less than conventional buildings, thus PBS provides the ideal platform for creating a Platinum LEED certified Zero Energy or Plus Energy Home. This is the best system for developing an Off-Grid self-sustaining home! earthshelter.com