After a lot of discussion and more than a little bit of hand-wringing, the EPA yesterday finally released its specifications and qualifications for data centers to earn the Energy Star rating. The rating will be available to both data centers and buildings that house data centers.

According to EPA, data centers use 1.5% of the electricity consumed annually in the United States, and that number is expected to double in the next five years. Improving data center energy efficiency by just 10 percent would save enough electricity to power more than 350,000 homes and $450 million every year.

In order to earn the rating, data centers have to use the EPA's Portfolio Manager web-based assessment tool. Applicants have to measure PUE, a fairly widely-accepted industry standard. If an applicant's facility measures in the top 25% of its peer group, then the Energy Star rating is awarded. The Power Usage Effectiveness (PUE) rating is measured at the UPS power supply.

The system is far from perfect. EPA admits that the Energy Star rating takes no account of the data center's geographic heating or cooling features, which most industry analysts agree can make a huge difference in a data center's energy draw. The rating also ignores the source of electricity and whether that electricity is generated by fossil or renewable fuels. There's also some question about how robust the qualification mechanism is for the rating, although EPA does point out that a "licensed professional" must independently verify the applicant's claims before the rating is approved. Time will tell whether the Energy Star rating becomes a meaningless sticker or a coveted award that motivates greater efficiency in the industry.