Data Center Uptime Has Minimal Impact on Energy Efficiency

by | Apr 8, 2010

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EPAdatacenterEUEA data center’s uptime has no impact on its energy efficiency, according to findings from a recent study from the U.S. Environmental Protection Agency (EPA), reports

Alexandra Sullivan, an engineer in the EPA’s Energy Star program for commercial buildings, told that the data didn’t show a significant relationship between tier and energy use.

Energy Star collected data on energy use and operating characteristics from more than 100 data centers between March 2008 and June 2009 (PDF) to determine their energy efficiency as part of its effort to develop an Energy Star Standard for data centers. The agency is expected to release the new standard on June 7.

With the EPA software, companies will be able to rate their data center’s energy efficiency from 1 to 100 by entering basic information about their energy use and operational characteristics.

The rating will be based on power unit efficiency, or PUE, a measure of the total power used by the data center, divided by the amount that actually reaches IT equipment. However, some critics think that the rating system also should take into account a data center’s level of redundancy and whether it uses free cooling.

Tom Deaderick, director of Tier 3-certified OnePartner’s Advanced Technology and Applications Center (ATAC), a hosting center in southwest Virginia said in the article that there wasn’t any reason why designing a facility for high availability necessarily hurts energy efficiency.

As an example, the ATAC facility uses several energy-efficiency measures including hot/cold aisles, blanking panels, perforated ceiling tiles over the hot aisles to exhaust hot air faster, grommets to prevent wasted cooling air and neat cabling in the subfloor, according to And it has plenty of redundancy with three computer room air conditioners (CRACs) to ensure uptime, instead of one recommended by Liebert.

The Uptime Institute said in the article that some of the biggest factors that do have a larger impact on a data center’s energy efficiency or PUE include idle capacity and the type of equipment used.

This week (April 6) the Green Grid, together with several global government and industry groups including the EPA have agreed to global data center energy-efficiency metrics centered on the PUE rating.

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