SOLAR HEATING AND COOLING GUIDELINES FOR WINDOWS

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A great deal of a building's summer heat gain comes in through its east and west windows. You can control this temperature buildup to a large extent by putting a screen of vegetation, a bamboo shade, a bris-de-soleil, or an extra pane of glass right over (but a little distance from) the glass already in the opening. This can, of course, become somewhat expensive if you have a large number of windows to cover . . . since the necessary trellises and/or framing must be built strongly enough to withstand wind, rain, etc.

For this reason, you may find it easier and less costly to fit your east/west windows on the inside with insulated shutters made of either fiberglass or urethane foam. That's shutters, not drapes. Interior drapes are less effective and can even increase heat gain within a house unless they're well-sealed around their edges and across the top and bottom.

South windows are a different story. If properly protected by an overhang, they can be shaded from the high summer sun and allowed to admit Ole Sol's warming rays when the sun is low in the winter sky. You can calculate just how far such a projection should extend out over any window by multiplying the height (in inches, feet, meters, or any other unit of measurement) of the opening to be protected by your home's latitude and then dividing by fifty. The overhang can then be constructed of either solid material or slotted . . . or covered with vegetation.

The colder the climate in which you live, the fewer north windows your house should have. Cover the ones you don't need—inside and out—with insulation and board them over. Or fit them with insulated internal and/or external shutters which can be opened during the summer but tightly fastened against frigid January winds.

North, south, east, or west (but especially east or west) . . . any window will admit less heat during the summer if it's protected by one or more large trees. Direct shade accounts for much of the saving, but the evapo-transpiration of the foliage (which most people completely overlook) is quite important too. The microscopic mist of water that a large tree expels into the air on a hot summer day can cool the surrounding atmosphere as much as a multi-ton air conditioner.

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THE ORIGINAL "SKY THERM" BY HAROLD HAY

Harold Hay's Sky Therm heating/cooling system has been called a big water bed covered by moving, insulated panels. And that's all it is.

A three-bedroom pilot model of the Hay design is now operating quite satisfactorily in Atascadero, California. The house is topped with panels mounted on tracks so that individual sections of the "roof" can be run back and forth to completely cover or largely expose the gigantic black plastic water bed underneath. The bed, in turn, lies directly on the ceiling of the rooms below.

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