The EPA will use Power Usage Effectiveness as the basis for assigning a a 1-100 rating to a data center, just as other building types receive a 1-100 rating.

On the scale, a building receiving a rating of 50 is average compared to similar buildings across the US, while buildings with a rating of 75 or higher are in the top 25 percent, and are eligible to earn the ENERGY STAR.

The use of the Green Grid developed metric is being seen as a major recognition of this approach to measuring energy use in the data center.

"As for next steps in the development of data center ENERGY STAR rating, the 12-month data collection is scheduled to conclude in June 2009. We will then develop the rating system and test it, and hope to make the rating available in our Portfolio Manager tool in January 2010," a spokeswoman for the EPA said.

Andrew Fanara of the US EPA Climate Protection Partnership Division made a presentation called "Opportunities in a carbon constrained world" which looks at challenges to the data center sector.

Background on how the data will be collected can be found here

Details of the EPA's portfolio manager and data collection can be found here.