Beaming down on the earth each day in vast quantities, sunlight can provide considerable warmth to homes. Whether you’re building a new home or remodeling an existing one, passive solar heating is a smart choice.

Our lives are made easier—or so we’re told—by an assortment of gadgets and gizmos, from computers to blenders to microwave ovens. Useful as these products may be, many of them live short and rather unproductive lives. There is one technology, however, that breaks the mold. It has only one moving part—solar radiation—and a lengthy warranty. It is called passive solar heating.

Passive solar heating can provide safe, comfortable heat and trouble-free service for as long as the sun continues to shine. This technology has been practiced for centuries—first by the ancient Greeks and later by the Anasazi Indians of the desert Southwest. Passive solar can be easily incorporated into new construction and can also be added to existing homes (see “Retrofitting for Solar Gain,” page 80). It’s amenable to a wide variety of architectural styles and climates.

If designed and built right, passive solar homes stay warm in the winter and cool in the summer with little, if any, need for environmentally damaging fossil fuels and noisy furnaces or air conditioners. And passive solar design and construction reap huge economic benefits at little, if any, additional cost. According to Ron Judkoff, director of the Buildings and Thermal Systems Center at the National Renewable Energy Laboratory in Golden, Colorado, passive solar homes may cost up to 3 percent more than conventional homes, but they can save homeowners tens of thousands of dollars over time.

And passive solar homes can be exquisitely beautiful. Generous south-facing glass and open interior designs create an inviting interior bathed in invigorating sunlight. Successful passive solar home building does, however, require knowledge, skill, and strict adherence to a set of guidelines.

Seek solar exposure

Passive solar homes require plenty of sunlight during the colder months. Ideal sites provide sunlight on the south side of a home from 9 a.m. to 3 p.m. If a site is shaded by trees, other buildings, or hills, look elsewhere. Solar gain will be dramatically reduced. Don’t be deterred, however, if you are building in a less favorable solar climate. Even in such places as Buffalo, New York, where sunlight in the dead of winter is a rarity, solar energy can provide up to half of a home’s annual heat requirement. Why? Although the sun shines infrequently during the winter, there is plenty of sunshine for comfort during the fall and spring. In the winter, solar design can tap into solar heat while a furnace or wood heater provides the bulk of the warmth.