Energy efficiency seems to make rational economic sense—the less energy used, the more money saved. Yet, in the real world it's actually competition with neighbors rather than cost savings that can drive people to turn down their thermostats, install insulation or simply switch off the lights when they leave a room. Such is the lesson of a host of efforts, ranging from a group called OPOWER's comparative use utility billing to switching from miles per gallon to rate vehicle efficiency to gallons per mile.

Now a new collaborative study from the Natural Resources Defense Council (NRDC) and the Garrison Institute's Climate, Mind and Behavior Project reveals that such simple actions—from taking one fewer flight per year to wasting less food—can add up. The environmental group estimates that if all Americans adopted 14 such steps over the next decade the country would avoid one billion metric tons of greenhouse gas emissions by 2020—or the equivalent of the entire annual greenhouse gas emissions of Germany.

"Much of this is eliminating waste—and most waste costs you money," says NRDC's executive director Peter Lehner. "If all Americans did take a fairly modest range of actions, most of which actually save you money, we can make a big difference."

The recommendations, in addition to flying less and wasting 25 percent less food, include: carpooling or telecommuting once a week (75 million metric tons of CO2 equivalent (CO2e) saved by 2020, if adopted by all Americans); maintaining your car or truck, such as keeping tires properly inflated (45 million metric tons of CO2e); cutting the time spent idling in a vehicle in half (40 million metric tons of CO2e); better insulation at home (85 million metric tons of CO2e); programmable thermostats set higher (80 million metric tons of CO2e); reducing electricity demand from appliances that are "off," so-called phantom demand (70 million metric tons CO2e); using hot water more efficiently, such as washing clothes in colder water (65 million metric tons of CO2e); buying EnergyStar appliances when old ones wear out (55 million metric tons CO2e); replacing incandescent lightbulbs with compact fluorescents (30 million metric tons CO2e); eating chicken instead of beef two days a week (105 million metric tons of CO2e); increased recycling of paper, plastics and metals (105 million metric tons of CO2e); "responsible" consumption, such as buying less bottled water (60 million metric tons CO2e).

"We make bad decisions all the time," says Sabine Marx, associate director at the Center for Research on Environmental Decisions at Columbia University, thanks to incomplete information or other barriers to action, like high up-front costs for things like insulation. Overcoming those "doesn't mean we have to manipulate people's minds," Marx says, but rather make good decisions easier.

For example, rates of organ donation vary widely within Europe, from 100 percent in France and Poland to 17 percent in the U.K. and just 4 percent in Denmark. The difference cannot be ascribed to different cultural views about organ donation but rather whether the country in question has a policy that is opt-in (check this box if you want to donate your organs) or opt-out (check this box if you do not want to donate your organs). "We think we're rational," says economist John Gowdy of Rensselaer Polytechnic Institute in Troy, N.Y. "But really it's the person who designs the question on the back of a driver's license who made the choice for us."

NRDC, the Garrison Institute and others hope to bring this kind of choice editing to the world of personal behavior. Part of this is a result of ongoing frustration with broader policy measures, particularly at the national level, when it comes to confronting climate change. "If Congress does enact something, it will be completely inadequate to the task," says Gus Speth, former dean of Yale University's School of Forestry and Environmental Studies. It would be a "first step," however, Lehner notes. The primary benefit of personal action is that it can start immediately, he adds.

But Lehner admits that his organization has no idea how to convince people to undertake these 14 steps in the next decade on their own. And there is significant danger that any energy efficiency undertaking ends up ultimately increasing energy use. "The rebound effect is quite clear," Speth notes. "You buy an EnergyStar refrigerator, but you buy two of them. We have to bring overconsumption into this. How do we get out of this consumerist trap we've been in?"

Economists Hunt Allcott of the Massachusetts Institute of Technology and Sendhil Mullainathan of Harvard University offer one answer in the March 4 Science: more funding for research into the "behavioral factors that influence energy consumption."

For example, programs like OPOWER's that compare electricity use among neighbors have been shown to reduce electricity use by 2 percent at a cost of 2.5 cents per kilowatt-hour. "If scaled nationwide," the economists wrote, "a program like this could reduce U.S. carbon dioxide emissions from electric power by 0.5 percent while actually saving $165 per metric ton of reductions." And all from a simple bar chart—paired with a smiley face for energy-efficient behavior—on an electric bill.