This story is part of a special series that explores energy issues. For more, visit The Great Energy Challenge.

Joel Spira wasn’t thinking much about saving energy when he began experimenting with the idea of interrupting the flow of electricity to a light bulb.  It was the late 1950s, and not only were Americans buying lots of new homes, they were hosting dinner parties with mood music. Spira thought that through the right lighting, he could provide the ambience.

“I wanted to create a nice environment,” recalls the 83-year-old physicist whose invention—the solid-state dimmer switch—has just been added to the Smithsonian Institution’s collection as one of the icons in the story of electricity.

But Spira’s work is not only found in museums. His company, Lutron, based in Coopersburg, Pennsylvania, about 50 miles north of Philadelphia, can boast of installing lighting-control systems in the New York Times building, the Statue of Liberty, the Bank of China and many more high-profile locations, some of which the company declines to make public. And although as a privately held company it does not release sales figures, Lutron claims that market penetration of its array of more than 15,000 lighting control products is substantial enough to save customers a total $1 billion in energy costs annually, and reduce the total U.S. lighting bill by 3 percent.

(See Related, Imminent "Lighting Revolution" Could Save Trillions of Dollars)

Inventing Ambience in an Apartment

It’s a business that’s come a long way from the makeshift lab where Spira began his work—the spare bedroom of his New York City apartment. He remembers his wife, Ruth Rodale Spira, wearing safety gloves and patiently testing his device on light bulbs for hours at a time, trying to find just the right balance of bright to dim.

Spira, a U.S. Navy veteran, had interrupted his physics studies at Purdue University to work in a top-secret World War II radar program. After he returned to Purdue and earned his degree in 1948, he worked for a decade designing guided missiles at the U.S. military aviation firm, Glenn L. Martin Company (one of the predecessors of Martin Marietta, now Lockheed Martin.) But deep down, he felt weaponry was not his calling.

“The Cold War mentality was really finally getting to me,” he said. “I wanted to do something else.”

That something else, it turned out, was testing ways to mute the light produced by ordinary incandescent bulbs. His vision was for a device that could control the level of light in an ordinary home the way stage lights could be controlled in a theater.

At the time, the only way to dim a light  involved using a device called a rheostat, which actually absorbed electrical energy, converting it into heat rather than light.

But by 1959, Spira had learned of a recently invented solid-state semiconductor device called a thyristor, a type of transistor, which could interrupt electricity instead of absorbing it, causing it to pulse instead of flow freely.

“We tried it out and, lo and behold, we were off to the races,” he said, explaining that it was much smaller than the bulky rheostats then used for lighting control, and could easily fit in an ordinary wall box.

The new switch was attractive and produced far less heat than its massive predecessors. And, although it didn’t seem to matter at the time, it used less electricity and extended the life of the bulb. Spira and his wife, after enough hours dimming bulbs in their New York City apartment, became convinced that they had hatched an idea for a new business.

So in 1961, they packed up their equipment and headed about 100 miles west, to Emmaus, Pennsylvania, where Ruth’s father, organic farming pioneer and publisher J.I. Rodale, had given them 1,000 square feet of space to set up shop.

Lutron, the company they founded there, became the first to mass-market dimmer switches. The company’s portfolio has grown over the years to include scores of other light control products; Lutron holds more than 3,000 patents globally. Employees now work on a sprawling campus of five buildings in Coopersburg, about 10 miles from the original facility.

And although other firms now make dimmers, Lutron is still the only company to create systems of dimmers and motorized window shades that control both electric light and daylight. The award-winning project that Lutron designed for the New York Times’s Manhattan headquarters, which opened in 2007, achieved a 72 percent reduction in electrical consumption over ordinary office lighting. The yearly energy savings are estimated at $315,100.

A Bright Idea for Saving Power

Spira first thought of the idea of promoting the energy-saving qualities of his lighting control devices not long after his company was founded, after reading an article in Foreign Affairs Quarterly by a sheik, an oil industry official from the Middle East, who made the argument that oil was being depleted, and that prices would rise in the not-so-distant future.

Spira said the author also pointed out a conclusion that he himself had reached years earlier—“oil is a war-making issue.”

At the time, though, Spira recalls, whenever he touted his devices’ energy-saving properties to friends, colleagues, and customers, he was met with the same bland response: “That’s nice.”

In another six years, the first Earth Day would build public recognition of the need to cut down on air and water pollution and build a healthy, sustainable environment. The Arab oil embargo, from October 1973 to March 1974, sent gasoline and fuel oil prices—and consequently prices of just about everything else—soaring and underscored the economic need to save energy.

Spira recalls that Lutron was ready, promoting its energy savings in a variety of ways. Still, Spira said, he viewed the environmental movement of the 1970s as primarily “lip service.”

Years later, he can now say he sees a genuine interest in power conservation—with people responding enthusiastically to the idea of saving energy by controlling both artificial light and sunlight.

(See Related, CFLs Could Cut World Energy for Lighting by 40 Percent)

Spira still goes to work every day, to a spacious yet simple corner office that’s scattered with books, papers, framed photographs, sculptures and the occasional slide rule. The window shades are set to rise and lower automatically, depending on the level of sunlight. The room lights turn on when someone enters the office, and turn off soon after someone leaves.

Amid all the high-end technology, one item is still conspicuously absent in Spira’s office. He adamantly refuses to use a computer and isn’t all that fond of hand-held calculators either.  After presiding over years of technological innovations, the inventor himself still prefers the simplicity of a slide rule.

Still, Spira looks to the future, envisioning more innovations, such as a network system to control the energy use of home and office electronics.

And he’s still b