Learn how others have designed and built their own homes using solar heated natural energy.
The home of Richard Davis in Bar Harbor Maine is a great example of passive solar heating.
While most everybody else is still just talking about the problems of the energy crisis, a few folks — such as the natural-energy leaders featured in a little book called Design for a Limited Planet — have quietly gone ahead and changed to cleaner, more basic, and less costly (in terms of both the individual and the planet) ways of heating and cooling their homes. Here, three of those pioneering families tell how they built their solar homes and describe what it's like to live on more intimate terms with Ole Sol.
Sydell and Steven Lipson:
Sydell and Steven Lipson (who was working in his father's florist shop in New Haven, Connecticut) wanted to build a "live-in" greenhouse — one large, plant-filled space that would get most of its heating from the sun. They had seen the experimental house with transparent plastic walls that architect Mark Hildebrand had built for himself in the woods, and they asked him for a refined version that could be bank-financed. The Lipsons' 4-acre plot is next to a forest preserve in the conservative township of Hamden, Connecticut. Their "street-conscious" neighbors "didn't want a bomb on the street," says architect Hildebrand, so the design of the house had to be appropriate to the community.
His design for the Lipsons' house appears to run counter to energy-saving theories because three walls of the house are transparent. They are made of two sheets of hermetically sealed polyvinyl chloride (PVC) plastic with an air space in between. Hildebrand had first seen the "pillow" walls used in Colorado and had tried it out on his own house before adapting the technique for the Lipsons' house. "I was experimenting with industrial materials to replace timber construction and thought of plastic because it was economical," he explains. The PVC he chose had good standards for longevity and visual clarity. But the material, used commercially for packing and wrapping, is thought of as disposable and, if subjected to stress, can become brittle and crack.
"We had to design the pillows and install them so that in erection or inflation, they would never be taxed," says Hildebrand. When inflated, the skin stiffens and the plastic forms both the interior and exterior surfaces. The pillows are clamped in place with extruded aluminum frames, similar to the ones that hold storefront windows.
The advantage of the plastic pillows, according to Hildebrand, is that they insulate as well as Thermopane glass — at about one-tenth the cost. However, because of the impermanence of plastic, the pillows will probably have to be replaced every three to five years, adding to maintenance costs.
Since so much of the house is transparent, its siting and profile had to be carefully planned. The roof is angled upward toward the south, creating a two-story living room with maximum exposure to the sun, while the north profile is low, heavily insulated, and windowless except for a back door. A roof overhang juts out enough to shield the pillow walls in summer but allows the sun to penetrate all the way to the north wall in winter. The living area is essentially one space for living and dining with a separate sleeping loft. The kitchen and bath are tucked under the low north side.
Rather than clear the site, the Lipsons kept as many trees as possible for natural climate control. In summer, the leafy trees shade the house, while in winter their bare limbs let the sun through. "Without ventilation," says Sydell Lipson, "the interiors can get up to 120 degrees." The house is designed for natural gravitation of air through vents — placed low on the north side and high on the south — that set up a strong air current through the interiors. "In the winter, we open the vents for two or three hours during the day and close them around the middle of the afternoon, when it's about 85 degrees, to conserve heat for the evening," she explains. On cold nights they start a fire in their Franklin stove, consuming about 3 cords of wood for the heating season.
Connecticut building codes stipulate that all four walls of a dwelling must be able to be heated to an average 68 degrees Fahrenheit, which necessitated an auxiliary heat source. The Lipsons chose a type of electric heater commonly used in theater lobbies. It is relatively inexpensive but eats up a lot of electricity. The Lipsons rely on their electric heaters only in the dead of winter. And yet the electricity bills are low, running an average of about $35 per month in winter and $40 for the coldest month, January.
Concessions must be made to living in a house with no central heating system. "Most people find our house chilly in winter," says Sydell, "but you learn to live and dress differently." The Lipsons also tend to use the house in zones. Some areas are warm, and others are allowed to become quite cool. The area within 12 feet of the wood-burning stove (which is set on tiles to absorb and radiate the heat) and the kitchen, which receives warmth from cooking, are used intensively.
The 36-by-32-foot house cost the couple $30,000 to build, but they economized by doing most of the work themselves. They had no building experience, nor were they even particularly handy, and it took them five months to build the house.
"The house suits our lifestyle," Mrs. Lipson says. "We like living in the woods. There is a certain joy in living in a cool environment. I now find I don't function very well in a house with central heating; it dulls me and makes me sleepy."
Norah and Richard Davis:
In its first year of operation, Norah and Richard Davis's solar house attracted two thousand tourists. "We finally had to put up a 'No Trespassing' sign," Richard Davis said. A transplanted southerner who went north to Bar Harbor, Maine, to teach philosophy at The College of the Atlantic, Professor Davis wanted to build a house out of recycled materials. On the advice of a colleague at the college, architect Ernest McMullen, his plans were expanded to include a solar heating system.
Locating recycled materials wasn't that easy, although the Davises did discover some interesting "finds:" the ballroom floor, doors, and 12-foot-long counters ... from the Evelyn Walsh McLean mansion (she was famous for owning the Hope Diamond, now in the Smithsonian Institution); structural timbers from a razed sardine factory; and a 2,000-gallon gasoline tank from a filling station to store their solar-heated water. "We didn't save much money using recycled materials," Richard says, "but we got materials we couldn't otherwise afford — the 1 1/2-inch solid wood doors and the quarter-sawn oak floors, for instance."
The Davis house is a compact, 1,300-square-foot building with an open interior plan for the living-dining-kitchen area, two bedrooms, and a utility room. Expenses came to about $30,000.
The solar collectors, a trim bank of 26-foot-long fiber-glass-faced panels, take up about half of the southern facade of the house; a greenhouse that opens to the kitchen and a deck occupy the rest of the front.
The house conforms to McMullen's — and a growing number of other architects' — concept of energy-saving design: that the right combination of materials for thermal mass, siting, and fenestration will keep a house significantly warmer in winter regardless of climate, without having to install expensive solar hardware. A design change advocated by engineers and architects concerned about fuel waste is incorporated in the Davis house: instead of conventional two-by-fours, the building is framed with two-by-eight studs to make a deeper recess for wall insulation. The house is insulated with 7 inches of fiberglass batts in the walls and 9 1/2 inches in the ceiling.
McMullen's solar design combines features of the basic water, air-to-rock, and greenhouse solar heat systems. The roof-mounted collector is composed of corrugated aluminum sheeting under fiberglass. Water is piped up to a feeder pipe at the top of the corrugated sheeting, where it trickles down the gullies and is heated by the sun to 120 degrees. The water collects in a trough at the bottom of the collector, and from there it flows down into a 2,000-gallon water storage tank that is embedded in a rock bin below the house. Beneath the rock bin is a manifold constructed out of standard concrete block. Air is circulated through the manifold, picking up heat from the rock bin, and then distributed through ducts to the rooms. The hot water supply is also tied into the solar system.
The Davises found that a larger-capacity storage tank would have given the house more heat. Their 2,000-gallon tank was supposed to store enough heat for three successive cloudy days — but they forgot to take into account Maine's strong coastal winds.
"If we have sunny winter days that aren't too windy, with temperatures around 30 degrees, we can just get by on the solar heating system. If it starts to go below 30 degrees and the wind picks up, we have to resort to our wood-burning furnace," Davis explains.
"We have adjusted to the fact that a solar house isn't capable of responding rapidly to changes in temperature," he adds. "For instance, if we come home at night and the inside temperature has dropped to the mid-50's, it takes a while for the stored heat to warm the house up to the 60's. In early winter, we keep the house at 70 degrees, but as it gets colder, we feel comfortable at 65 degrees. You live differently in a solar house," he says. "We are much more aware of what the weather is doing."
David and Barbara Wright:
Environmental architect David Wright developed a simple way to heat a house by the sun that has worked in different regions and different climates. A Berkeley-educated ex-Peace Corps member, Wright was one of the original members of Sun Mountain Design, in Santa Fe, New Mexico, a non-profit group of engineers, builders, and architects involved in solar-tempered design. They approached land use, development, design, and research synergistically, learning from their various disciplines. David, like the others, prefers non-mechanical sun-heated houses to those with complicated systems involving collectors, storage, and circulation systems.
His own house on the outskirts of Santa Fe, in the foothills of the Sangre de Cristo Mountains, is a prototype of the non-mechanical structures he advocates. The only visible hardware is a small separate solar collector that stands several yards from the house on the south slope and supplies the house with hot water.
In appearance, the house blends harmoniously with the native New Mexican architecture. It uses adobe brick, and the roof overhang echoes the traditional vigas , or roof beams, that extend out through the walls of old adobe houses. Its inspiration goes even farther back — to the twelfth-century pueblo dwellings at Chaco Canyon, considered by many to be America's first solar-heated habitations on a grand scale. At Chaco Canyon, the multifamily structures that were archetypal apartment buildings to house a whole community were built in an arc. The windows and doorways faced south, into the sun, while the backs of the pueblos were shielded by the hillside, giving them protection from northern winds.
The Wright house reflects that same design. From a bird's-eye view, it is shaped like a semicircle with a flat front. The curved walls are 14-inch-thick adobe brick with 2 more inches of polyurethane insulation covered by a thick layer of stucco. The flat front, facing south, is a two-story-high window wall made up of double-glazed sliding doors. An overhang shields the windows from the hottest summer sun. In contrast to the front, the three remaining sides of the house are surrounded by an earth bank and broken only by a few small windows set high up to act as vents. On the east, the main entry door is protected by a vestibule that creates an air trap so warm house air can't escape each time the door is opened.
David, with his wife, Barbara, built the house almost single-handedly with some subcontracting for electrical and plumbing work and a couple of part-time crews who worked two-week stints. The house took them less than six months to complete and cost the couple around $13,000, not counting their own labor. The interior is basically a two-story-high room with a balcony. Although the house is small, the window wall gives the interior a feeling of generous space.
David Wright's concept of a solar "heat sink," such as the one they adopted in this house, was popular in the late 1930's. Houses were marketed and sold as "solar houses",, but they never adequately solved the basic problem: what to do with the excess heat during the day and how to stem the heat loss at night. (Night losses usually exceed the daily heat gains.) Superior insulation and the thermal building mass of adobe were Wright's solution to that problem. To augment the natural insulation provided by the adobe walls, fifteen 50-gallon water-filled oil drums, buried beneath the living room window, soak up the sun's warmth. Water holds about four times as much heat as adobe, and also absorbs it and gives it off faster. To further reduce heat loss at night, accordion-fold shutters made of canvas and 2-inch polyurethane panels are raised and lowered by a hand-operated crank and pulley to cover the vast expanse of the window wall at night.
Since completion, the house has required practically no maintenance. The Wrights found that space heating based on the concept of thermal lag follows natural rhythms and puts the body's metabolism in tune with it. "The body heats up and cools down gradually with the building," David explains. During the winter months the Wrights found that the house stores about five days' worth of heat, enough to carry through an average cloudy period in New Mexico. For auxiliary heat, they have a wood-burning Franklin stove, which uses less than a cord of wood a year.
This feature was excerpted from Design for aLimited Planet by Norma Skurka and Jon Naar, copyright © 1976 by Norma Skurka and Jon Naar, reprinted by permission of Ballantine Books (a division of Random House, Inc.)
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