Utility companies have been trying for years to get their customers to be more energy-efficient, but with limited success. But a little experiment with the Sacramento Municipal Utility District in behavioral science proved surprisingly effective. It showed that while Keeping up with the Joneses may be a clichÃ©, it can motivate people to conserve. Starting in April 2008, the utility began sending out statements to 35,000 randomly selected customers, rating them on their energy use compared with that of neighbors in 100 homes of similar size. Customers who were especially energy-efficient earned two smiley faces on their statements, while customers who weren't as efficient got frowns. When Sacramento analyzed the results six months later, they found that customers who received the personalized statements cut their energy use by more than 2 percent, which is the equivalent of taking 700 homes off the grid. As a result, the approach has been picked up in several cities, including Chicago and Seattle. Positive Energy, the software company that created the reports and contracts to produce them, says it will be serving over a million utility customers by the end of 2009. The hope is that what has been learned in the energy arena can be applied elsewhere, like water conservation for starters.