COLOSOL'S EARTH-SHELTERED

Image Gallery While the colosol structure's garage and air-lock entryway are located aboveground, and the living area is set partially belowground and is partially earth-sheltered.

Passive solar and underground housing get together in Dillon, Colorado.

ENERGY SAVER

A few months back, MOTHER received a tip from reader Barry Goldberg about a passive solar, earth-sheltered house set high in the Colorado Rockies . . . near the resort town of Dillon. Barry's description of the building — along with the knowledge that the extreme climate at the village's 9,300-foot elevation would put the energy efficiency of such a shelter to a true test — led one of our staffers to visit its builder, Michael Wiggins . . . who operates an energy-conscious contracting company called Colosol Construction.

Mr. Wiggins' subterranean shelter is located in a small development which sprawls across a high mountain meadow, but the house—with its attractive aboveground garage and entryway on the street side—doesn't appear to be out of place amidst the more conventional vacation cottages. In fact, the "normal" portion of the structure (which encompasses a total of 625 square feet) tends to obscure the low roofline of the earth-sheltered living area behind it ... making the dwelling look like a tiny house with a large garage.

Mike chose to place the floor of the underground portion of the house four feet below the earth's surface . . . to allow for practical septic field drainage on his relatively flat lot. (An eight- to ten-foot-deep excavation—which would have been necessary in order to go completely subterranean — would have involved a tremendous amount of expensive backhoe work.) Then, after the four-foot-deep hole was dug, the removed earth was used to berm the walls which protrude above ground level ... creating a combination underground/earth-bermed structure.

The walls themselves are made of eight-inch-thick concrete . . . with the exception of the long living room bulwark, which is formed from hand-laid rock. All external walls are insulated with four-inch styrofoam for the first two feet, and a twoinch layer of the same material is used everywhere else . . . even beneath the fourinch foundation slab. Furthermore, the rock wall is capped with lumber to avoid forming a heat sink between the earth-bermed wall and the upper air exposure. A total of 95 yards of concrete and 17 tons of rock went into the construction of the building . . . to provide strength and insulation.