The Energy Star rating for data centers is here. The US Environmental Protection Agency announced on Monday that stand-alone data centers or buildings that house them can now receive the agency's official recognition for being in the top percentile of the most energy efficient buildings in the category.

The EPA will issue the Energy Star label to data centers whose Power Usage Effectiveness falls into the lowest 25 percent of their peers. Receiving the label requires that a building's PUE be independently verified by a licensed professional, who signs and seals an application document which is then sent to the EPA for approval.

The agency's existing Energy Star rating for commercial buildings worked the same way, rating building energy performance on a 1-100 scale and issuing the label to buildings in the top 25 percentile. The process of determining energy efficiency of data centers, however, required a different approach than other commercial buildings.

PUE, the metric EPA chose to use to determine data center energy efficiency, was developed by The Green Grid, a data center industry group. In early July, TGG announced that it had become an official tech advisor to the agency. In the same announcement, the group said its metric became officially recognized by the EPA, as well as by government agencies in Europe and Japan.

In addition to buildings, the EPA has an Energy Star rating system for electronics, including servers, and is in the process of developing one for data center storage equipment. Energy Star for UPS systems is in the early stages of development.