The feds rate the energy efficiency of everything from air conditioners to dishwashers—and now you can add computer servers to the list. The U.S. Environmental Protection Agency (EPA) this week announced new Energy Star ratings for servers, a move designed to up average energy efficiency by 30 percent.

The program is part of a larger government initiative to green data centers, which used more than 60 billion kilowatt-hours—at a $4.5-billion price tag—in 2006, the EPA noted in a report to Congress the following year. In the wake of the findings, the Bush administration EPA pledged to craft a plan to slice energy usage by 10 percent by 2011. If all the new servers sold in the U.S. were to comply with the new Energy Star specifications, server owners could save $800 million annually in energy costs—and the reduction in climate-change-causing greenhouse gas emissions would amount to taking a million cars off the road.

Servers will gain Energy Star status if they give off relatively low amounts of heat (allowing data centers to cut down on energy-intensive air conditioning), continuously measure energy use and temperature in real time (helping consumers better manage use) and include information sheets (akin to those yellow stickers on your hot water heaters and dryers) that list potential energy savings.

Some green tech advocates are also pushing for servers that automatically go into "sleep" mode when they're not in use. The University of Michigan recently released a report showing that annual energy use linked to servers could be cut by as much as 75 percent if servers were capable of going to "sleep" and waking up quickly the way personal computers do.

Image of an Energy Star tag on a cell phone charger courtesy of Handolio via Flickr