The Thermal Envelope Home

Image Gallery A wintry day provides day provides the perfect setting for the undeniably beautiful Smith residence. Sunlight reflected off snow can furnish up to 30% of the home's heating needs STAFF PHOTOS

An ancient Japanese proverb states that "the simplest solution is the best". If that's the case (and we think it is!), then this attractive house—nestled high in California's Sierra Nevada mountains—is one of the better solar-heated homes around, since its design alone allows it to store heat during the sunlight hours and release that warmth, slowly, to the interior throughout the day and night.

In order to find out more about the unusual dwelling, MOTHER sent staffer Richard Freudenberger to Olympic Valley, California where—surrounded by several inches of snow and subfreezing temperatures—Richard talked to owner/designer Tom Smith (in a comfortably warm atmosphere) and questioned him on various aspects of the house . . . including the all-important "passive" approach to its heating.

The number of solar houses being designed, built, and lived in grows by leaps and bounds every year. And, more often than not, these "newcomers" on the solar scene are passively heated. Let's face it... if you're building a house from scratch, why bother with pumps and pipes (which are not only expensive, but are also subject to periodic failure) when you can get the same results from a system that uses nothing but a well-planned design to achieve its goal?

Furthermore, "active" heating systems require a collector . . . something that [1] most likely will be commercially produced and costly, [2] will probably detract from the beauty of the house, regardless of how aesthetically pleasing the structure otherwise is, and [3] will usually necessitate additional engineering and construction considerations.

These factors helped Tom Smith and his architectural advisor, Lee Butler of San Francisco, decide to go with a totally passive system. And—after 20 months of research and a full year of living in the house—Mr. Smith has no regrets. If anything, the structure's efficiency has exceeded his expectations . . . especially since many days are overcast in the Sierras, and even in bright weather the trees native to the area block much of the afternoon sun.

HOW THE "ENVELOPE" WORKS

The Smith house has two major parts: [1] the load-bearing outer shell, which incorporates a 300-square-foot greenhouse on its south side, and [2] the inner shell, which is separated from the exterior framework by a 12-inch air space all around (except on its east and west walls, which are shared with the "outside" structure).

As the low winter sun beats down on the building, its rays pass through the double-strength glass on the face of the greenhouse (a good deal of which is angled to catch more light), heating the air within. That warmed air rises, drawing behind it—through quarter-inch spaces between the planks of the greenhouse floor—cooler air from the crawl space below the house.