A home with a built-in comfortable temperature

A built-in temperature? That’s right. A built in temperature! By the proper design and layout of building materials, one can manipulate natural heat flow to produce a structure that needs neither air conditioning nor a furnace in just about any climate on Earth. The first example was designed by the CoolScientist and built in 1979-80 in Missoula, Montana, USA. All summer long it cooled itself naturally, storing the heat in the earth around the building, and using that heat to keep it warm all winter. All summer long, its highest recorded indoor temperature was 77º F (23º C) and the coolest was 66º F. (19º C)—without requiring one drop of commercial energy to do it. While outdoors, Montana typically ranges from over 100º F (38º C) in the summer to -20º F (-28º C) in winter, with an annual average of 43º F (7º C)

The method of producing a continuously comfortable climate is called Passive Annual Heat Storage, and is the subject of the CoolScientist’s first book by the same name that has sold round the world in 25 countries, and made the cover of Popular Science, Mother Earth News, and Rodale’s New Shelter.

The principles of physics employed are simple. The temperature through about 20 feet (6 m) of earth is constant, and is a reflection of the average annual air temperature at the nearest open surface. The earth sheltered home, not nearly so deep, has both the home, and the dirt around it isolated from the outdoor temperatures with a large insulation/watershed umbrella. Thus the “nearest” open surface is not the out-of-doors, but the inside walls of the home.

By controlling natural heat flow into and out of the home on an annual basis, the body of earth 20 feet out, around and under the building will naturally climatize itself to the new artificially-produced temperature inside the home.

The interior of the home will then maintain itself within a few degrees of that temperature without the need for commercial energy or equipment to make it work…and thus, it becomes a built-in temperature.

In cold climates, solar energy shines in the south-facing windows (in the northern hemisphere.) Whenever the temperature attempts to rise, the natural conductive heat flow pulls the extra energy back into the dirt around the building—all year around. Then whenever that temperature attempts to fall, that heat turns around and comes back naturally to keep the home comfortable all year around.

In warm climates, the windows are faced away from the sun so that the building will lose heat at night over the annual basis. By establishing an artificial average annual air temperature that is cooler than the outdoor average, the home remains continuously comfortable.

The Insulation/watershed umbrella is made of two layers of expanded polystyrene insulation sandwiched in between three layers of polyethylene plastic. It’s laid out like shingles to shed underground water, and keep the building and the earth around it dry.

The building itself is made of concrete, and has been especially engineered to hold a dirt load of about 4 feet (1.2 m) The “Geodome” in Montana also happens to be an earth sheltered geodesic dome, but square buildings work just as well from a thermal standpoint.

Just because it has dirt on the roof, doesn’t mean that it has to be a cave inside. With its large south-facing windows, the home is airy and bright with lots of natural light inside. In fact, computer analysis shows that it actually works better because it is painted white inside than some darker color. It provides a very pleasant environment, that’s always comfortable. Regardless of skyrocketing fuel prices.

(You can learn more about earth sheltered homes with the exciting E-book Passive Annual Heat Storage, Improving the Design of Earth Shelters, at www.coolscience.info. Click on “Extraordinary E-Books.” Questions? Email us at coolscientist@rmrc.org. © 2005 by CoolScience.)