Strong has based his professional life on two design principles that he repeats like mantras--"solar energy" and "energy efficiency." Fresh out of engineering school in the early 1970s, he found work on the Trans-Alaska pipeline measuring the energy-saving capacity of the housing that protects the pipe's giant valves. One of his jobs was to scour every surface for heat leaks, and he found plenty in surprising places: every nail and screw provided a tiny escape route to the frigid air outside that could plunge to -75 degrees Farenheit.

"My fundamental awakening was that it is easier to save a unit of energy than to produce one," he says. To understand that, all he had to do look out the outlandish construction efforts that went into laying the pipeline. "I kept wondering why are we investing these billions of dollars for only a few decades worth of oil."

A few years later Strong had another ephiphany. This time he was assessing the reliability of solar-powered relay stations on a telecommunications cable that crossed a desert in Cameroon. The stations used photovoltaics, then a new technology used mainly by NASA on its satellites. "I was blown away," says Strong. "Nothing was wasted. The energy was entirely renewable. It was just--whew!"

Now 48 and the president of his own architectural and engineering firm, Solar Design Associates, in Harvard, Mass., Strong has designed and consulted on scores of what he calls "environmentally responsive buildings." Latest on the list is a 12-story-high cube for the Discovery Science Center in Los Angeles. His clients include Disney, Lucent Technologies and a handful of utilities that appreciate the value of being able to buy electricity from customers during summers when demand for energy is high.

But Strong's "passion" is designing homes for individuals and families who can afford his expertise. For actor Robin Williams he built a hilltop array of solar collectors that looks a field of giant sunflowers. Clients like Williams who are willing to pay a premium enable him to try out innovative designs. "Comfort rules" is his credo, which he contrasts with solar-energy and energy-conservation philosophy following the 1974 Arab oil embargo. Then, thick solar panels of questionable efficacy angled up from rural dwellings as a source for hot water. Thermostats turned down low tended to keep homes uncomfortably cool. "It's so nice walk up on a winter morning in a bedroom that's 76 degrees," Strong says.

While designing residences may please the client, it does not necessarily convince many others of the benefits of solar. To counteract what he calls "blissful ignorance" of solar energy among architects and policymakers, Strong criss-crosses the country to drum up acceptance. He delivers two messages: the first is that a lifestyle based on fossil fuels puts this country in a "morally indefensible position;" the second is that solar energy "is here, it works, it's reliable, and it's comfortable." What more can be asked of a free energy source?