A study in California showed that when the monthly electric bill listed the average consumption in the neighborhood, the people in above-average households significantly decreased their consumption.So simple that I don't know why all electric companies don't adopt this.
Meanwhile, the people with the below-average bills reacted by significantly increasing their consumption — not exactly the goal of the project.
That reaction was avoided when the bill featured a little drawing along with the numbers: a smiling face on a below-average bill or a frowning face on an above-average bill. After that simple nudge, the heavy users made even bigger cuts in consumption, while the light users remained frugal.
via NY Times