"There wasn't much knowledge out there and a lot of people rushed in and called themselves solar experts," Aaron told me. "A lot of them didn't know anything about solar energy and many people installed solar heating just to get the tax break.

"But a good deal did get accomplished and a real industry started to form, then the Reagan Administration came in and swept away all of the tax incentives for alternative energy sources. That just killed the movement. Of course, they kept all the tax breaks for the oil and coal industries, they even increased them."

Solar energy is also clean and safe. "Cleanandsafe," as solar advocates will tell you. They imply, or may even tell you outright, that nuclear energy is dirty and dangerous. In elementary school, those were fighting words for me, since my father designs nuclear fuel. I viewed any attack on nuclear power as an insult which could be settled only with a fistfight at recess.

Discussions about energy policy, even among friends, can quickly become emotionally charged since the issue involves fundamental values. Solar advocates believe in walking to work, eating organically grown foods, and living simply, like Thoreau. Proponents of nuclear energy believe in General Electric, General Motors, and General Foods.

Our first stop was in Lexington, at Doug Holmes's place. Doug Holmes is a consulting engineer and makes his living giving practical advice. He has waged a lifelong battle against inefficiency and sloppy design.

Not so long ago Doug helped design a sewage treatment plant that forgoes modern technology for more traditional means. "People aren't the only ones with sewage to treat," he told us. "Every animal out there makes some, and Nature takes care of it." Modeled on a wetlands, his plant is a series of tanks open to sunlight. The sewage flows through so slowly you can't see it move. At the front end, there are only bacteria. Farther down you can find worms, shrimp, and then fish. "When we wanted to start the plant running, we needed all the little beasties you find in nature, so we went to a few ditches around Providence and collected a bucket of slop, then poured that mess into our tank."

When we all arrived Doug led us down to the greenhouse on the south side of his house. When the house was built in 1979, he purchased the greenhouse armature from a garden store that was going out of business. "If you are ever going to build a greenhouse, use sliding-door glass. Sliding door replacements are the cheapest double-glazed glass on the market."

The floor of the greenhouse is a right triangle with the legs, 15 feet long, pointing south-east and south-west. In the winter, when the sun is low in the sky, the greenhouse receives light throughout the day. In summer, the house walls shade the greenhouse in the morning and evening so that sunlight enters for only four or five hours.

In winter, the sun heats the greenhouse air which then flows up a vent at the top of the greenhouse, through the attic, and down a space in the northern wall. A blanket of heat envelopes the whole house.

The greenhouse cost $10,000, but Doug figures that he has saved that much, easy. "Some people say you have to be a little crazy to build a house in New England without a furnace, but once you make that leap of faith, you need no blower, no ducts, no radiators. You start 5000 dollars ahead."

Under the south-facing windows pigmented concrete floor absorbs heat during the day and radiates at night. "We call that poor man's Italian tile. The concrete costs 50 cents a square foot, tile would do the same job but costs ten times as much," Doug said.

The coldest the house gets is 55 degrees Fahrenheit. Doug spends 50 dollars a year to heat his home on a half-cord of wood that is burned on the coldest winter days. Two-thirds of the heating is done by the sun, ten percent from the two pot-bellied stoves. The rest comes from "heat of occupancy": the oven, the refrigerator, light-bulbs, and people. Doug looked at the 15 of us in his living room. "Right now, all of you are giving me 100 watts," he said.

Someone asked, "What about air management?" Doug replied, "We quit having colds in the winter when we moved into this house. It is the moisture from the plants. Everybody else gets all dried out. Our air management consists of opening the windows for ten minutes on a warm winter day if the humidity gets too high."

As Doug talked about his house, the phrase "design criteria" came up again and again. There are, he said, "no flourishes, no filials, no shades, no shutters." But that doesn't mean the house lacks elegance, just that everything has a purpose. "One thing that always bugged me about houses was that you can't get at anything, so everything here is accessible," Doug said. "You open a panel in the wall to get at the wiring and plumbing."

"We used to keep a book for visitors to sign, but got tired of it. We've had over 3000 people come and see the house, but as far as I know no one has built another house like it."