The professor takes great care in how he speaks. He knows when to talk and when to smile, when a laugh can disarm his listeners and draw them into his point. When answering questions, he'll pause mid-sentence to repeat the questioner's name, then continue.

Lately he has been pondering this question: For decades, advocates have tried the emotional and rational sells for saving energy. Turn off the lights, program the air-conditioner, unplug idle appliances, and it'll either benefit the planet or save piles of cash. While these tactics have picked up some steam, millions of Americans remain unmoved.

Influencing what people do is Robert Cialdini's business. Formerly of Arizona State University's psychology department, he wrote one of the best-selling books on persuasion of all time. "Influence" came out in 1984, and it's reached five editions since. Legions of college students and CEOs have pored over it; Cialdini presents its still-salient findings at motivational talks.

What made "Influence" so compelling was its simple distillation of decades of research into six principles, or "weapons," of persuasion.

For example, people are swayed by authority: They are more apt to jaywalk if a fellow in a well-tailored suit leads the way. People find more appeal in things that seem scarce: They say a cookie tastes better if it comes from a near-empty jar rather than a full one.

Now, the professor has trained his "weapons of influence" on how people use energy. For two years, he's been "chief scientist" at OPOWER, a firm that studies utility customers, then advises the utility on how to save energy. Currently, 30 utilities have managed to cut energy use by at least 1.5 percent; some regions lead at 3.5 percent.

Compared with other strategies -- efficient appliances, upgraded power plants, new grid technology -- it has cost them next to nothing.

The key, according to Cialdini, has been reframing the pitch behind energy efficiency.

Savings and moral approaches fizzle
According to some researchers, the things people do every day -- driving, showering, mowing the lawn -- cause 33 to 40 percent of greenhouse gas emissions. Experts say these actions are packed with cheap ways to cut waste, but mysteriously, people just aren't doing them.

Cialdini thinks this is because the campaign has focused on money and moral appeals -- things that motivate less than the weapons of influence.

The professor began studying environmental behavior in the 1980s, when the 1970s' energy crisis loomed large in the public memory. Over the decades, his research would include work on recycling, littering, energy use -- even "environmental crimes" like stealing mementos from a petrified forest.

Late last decade, as he contemplated retirement, national governments had approached him with questions about energy. They had tried subsidies, incentives, educational campaigns and more -- Could there be a cheaper way to persuade people?

In other words, Cialdini says, they sought the "sweet spot": where a tiny nudge could do what millions of dollars could not.

"It's easy to produce benefits by throwing huge amounts of money at them, or resources, but we don't have limitless resources or pots of money," he says. "That place, big change for small levels of effort, is the sweet spot."

Then, two and a half years ago, the founders of OPOWER shared their goal: to understand people, and to help a utility find its "sweet spot."

If the Jones' save energy, you might
Cialdini finally left academia in mid-2009, but in a sense, his experiments could continue. OPOWER asked him to design small-scale studies to see whether small prods could get customers to change their energy habits.

In one San Diego suburb, Cialdini's team went door to door, ringing the doorknobs with signs about energy conservation.

There were four types of signs, and each home received one randomly, every week, for a month. The first sign urged the homeowner to save energy for the environment's sake; the second said to do it for future generations' benefit. The third sign pointed to the cash savings that would come from conservation.

The fourth sign featured Cialdini's trick: "The majority of your neighbors are undertaking energy saving actions every day." (This was true -- Cialdini had surveyed the neighborhood and found that most residents were taking actions, however small.)

At the end of the month, Cialdini and his team read the homes' meters. They compared the four types of homes to other homes that had received no signs at all. The only sign that made a difference was the one about the neighbors.

"We think of ourselves as freestanding entities: 'Oh, I'm independent of the influence of those around me. I'm an individual,'" Cialdini says. "In fact, we are swept by that information in ways we don't recognize."

Psychologists say these are "social norms" at work: People tend to watch others to figure out the right thing to do -- provided there are multiple people doing it and that they're considered similar to oneself.

Cialdini says that ends up fueling a more effective -- and cheaper -- way to get people to save energy than telling them how much cash they'd save.

Flying with the flock of neighbors
"If your neighbors are saving money, or saving energy, it means you can do it too," he says. "It's feasible for you to change, to save, because your neighbors are doing it. People just like you are doing it."

"And that feasibility is something that is inherent in information about what your neighbors are doing that's not inherent in information about how much money you could save."

The flocking tendency is so strong, in fact, that when energy misers learn they're better than average, they often relax and revert to wasteful habits.

OPOWER found this in neighborhoods where each month, they sent every resident a letter with two bits of information: the average energy use of her neighbors and where her home stood by comparison.

Homes using more than average followed the herd: They started saving energy. Homes using less, however, began to let their use creep up toward the average.

Cialdini feared the two effects would neutralize each other. So he decided to target the below-average energy users with a special message.

"When we sent them the message saying you're doing better than your neighbors, we put a smiley face emoticon next to their score," he said. "And that kept them down below what any of their neighbors were doing."

With these customers leading the way, he says, the neighborhood average drops each month. As always, energy wasters wake up and trend toward the average; those below the average relish their smiley face.

For the price, Cialdini says, utilities find the approach persuasive. "And in this case you don't even have to put a sign on the door," he chuckles. "You just let the post office deliver it. For the price of second-class postage."

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC., 202-628-6500