The Energy Star program has been successful in the past, covering more than 50 types of products including computer monitors, ceiling fans and washing machines. The EPA has said the server program was the hardest product category it has tried to do.

It is now working on an Energy Star for storage equipment, a first draft of which could be covered in the coming weeks, and eventually it plans to tackle network gear as well.

Energy efficiency has become a focus for many companies because the power and cooling capacity has become strained at their data centers. The increasing power and density of servers has made them a significant operational cost for many organizations, which also face pressure to reduce carbon emissions.

The Energy Star logo will appear alongside the system specifications sheet on each vendor's Web site. The EPA will also publish qualifying models and configurations on its Web site.

Vendors are so keen to tout the efficiency of their products that some will issue press releases in the coming days touting their Energy Star status, Fanara said. The specification hasn't changed significantly from the last issued a few weeks ago, so vendors have had a pretty good idea which products would qualify.