Smart meters alone are not enough to save energy and money, according to a new study.

Significant savings are possible, however, and consumers save more when information is tailored to them. Programs that focus on energy efficiency and conservation also produced more savings than those that sought to move energy use to off-peak hours.

Those are some of the findings of a review of 57 studies conducted over three decades for the Washington-based American Council for an Energy-Efficient Economy (ACEEE).

Smart meters are part of energy efficiency efforts to develop a smart grid that allows communication between power producers, transmitters and consumers.

Most take advantage of the Internet and advanced computer and communication technology.

ACEEE Executive Director Steven Nadel said the key is not only the ability to communicate, but what is communicated.

"The more useful, readily understandable and actionable information you can provide, the better," Nadel said. "You don't just want to inundate consumers."

While the most widely used programs are called enhanced billing -- in which information on power pricing is provided in monthly bills or separate mailings -- devices are being developed to provide consumers with more timely information, including desktop orbs that glow different colors during peak and off-peak times, and Web portals.

"One of the nice things about the orb is it's a very simple color, you don't have to get out your calculator and say 'So, what does this information mean?' You know green is good and red is bad," Nadel said.

The group said the review found U.S. consumers could cut household electricity use as much as 12 percent and save $35 billion or more over the next 20 years if utilities go beyond smart meter initiatives and include a wide range of energy-use feedback tools.

Nadel said smart meters also don't have to come only from power companies.

Google, for example, has a smart meter program that allows consumers to view usage information provided by utility smart meters and energy monitoring devices online.

"We're beginning to see a lot more interest in this field altogether," said John (Skip) Laitner, ACEEE's director of economic and social analysis. "So who knows what intriguing arrangements or devices or feedback relationships with consumers may emerge?"