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Given the Obama administration's ambitious new effort to reduce greenhouse gas emissions, we can safely expect a new series of campaigns urging people to use less energy. But what's the most effective way to frame such a request?

The obvious answer, at least from a cynic's point of view, is to emphasize the notion that saving energy means saving money. But new research from Great Britain finds a more altruistic appeal may actually be more effective.

It found a "smart meter" that calculated one's carbon dioxide emissions led people to think more about the environmental impact of their actions, and increased their intention to behave accordingly, than alternative displays that showed either monetary costs or kilowatt hours.

Most Americans express concern about the environment, but few connect it directly to their personal actions.

The results suggest "the environmental motivation for reducing energy use should not be ignored, and may be a more significant driver (than cost) for environmental behavior," writes a research team led by University of Nottingham psychologist Alexa Spence. Its study is published in the Journal of Environmental Psychology.

The researchers describe two experiments, one of which featured 102 undergraduates. Each participant was given one of three versions of an online home energy calculator: One that displayed energy use in terms of kilowatt hours, one that did so in terms of cost, or one that estimated carbon emissions.

After working with the calculator to calculate their own usage, the participants filled out surveys measuring their attitudes toward climate change and energy. They also reported the extent to which they were willing to undertake "common, everyday actions relating to energy reduction and environmental conservation," such as turning off lights they weren't using.

"We found that a CO2 framing of energy reduction led to climate change becoming more salient for our participants," Spence and her colleagues write. "Increased salience of climate change in turn resulted in increased intentions to undertake (pro-)environmental behavior."

It's not clear why a carbon calculator proved more inspirational than one that focused on money spent (and, potentially, saved). The researchers noted that the cost savings on a short-term basis are quite small, and suggest that they might prove to be a more significant motivating factor over time.

It's also unclear why the carbon emissions readings increased environmental concerns among many, but not all, of the participants who used that version of the calculator. Only those who made the mental leap from one to the other expressed an increased likelihood to change their behaviors.

Given these question marks, the researchers conclude that there is "unlikely to be a simple message that can effectively engage everyone."

"We suggest that costs are not ignored in communications (designed to discourage energy usage)," they write, "but that environmental considerations should also be highlighted."

It seems like a sound idea. Most Americans express concern about the environment, but few connect it directly to their personal actions. A daily reminder of our carbon output, displayed on a meter in the garage or near the back door, would make it much harder to be oblivious—and might even inspire new behaviors.