Eight groups involved in the data center industry met last month and agreed on "guiding principles" for measuring energy efficiency in data centers using the Power Usage Effectiveness standard popularized by The Green Grid.
The Jan. 13 meeting involved representatives of The Green Grid, the 7x24 Exchange, The Uptime Institute, the Silicon Valley Leadership Group, the U.S. Department of Energy, the U.S. Environmental Protection Agency’s Energy Star Program, the U.S. Green Building Council, and the HVAC industry group ASHRAE.
"This guidance is meant to help the industry have a common understanding of energy efficiency metrics that can generate dialogue to improve data center efficiencies and reduce energy consumption," according to an announcement by ICF International on behalf of the EPA. "Member organizations are committed to applying and promoting these guidelines to their programs."
The guidance focused on three principles, according to ICF:
- Power Usage Effectiveness (PUE) using source energy consumption is the preferred energy efficiency metric for data centers. PUE is a measurement of the total energy of the data center divided by the IT energy consumption.
- When calculating PUE, IT energy consumption should, at a minimum, be measured at the output of the uninterruptible power supply (UPS). However, the industry should progressively improve measurement capabilities over time so that measurement of IT energy consumption directly at the IT load (i.e. servers) becomes the common practice.
- For a dedicated data center, the total energy in the PUE equation will include all energy sources at the point of utility handoff to the data center owner r operator. For a data center in a mixed-use building, the total energy will be all energy required to operate the data center, similar to a dedicated data center, and should include IT energy, cooling, lighting, and support infrastructure for the data center operations.
The PUE metric, which has been popularized by The Green Grid, compares a facility’s total power usage to the amount of power used by the IT equipment, revealing how much is lost in distribution and conversion. An average PUE of 2.0 indicates that the IT equipment uses about 50 percent of the power to the building.
But not all PUE measurements are created equal, and there’s been much discussion about the various ways to gather the data. The Green Grid has outlined levels of PUE measurement, based on the particulars of where and when measurements are taken. The Jan. 13 meeting also addressed issues in consistency of PUE reporting, industry observers say.
"This appears to be an effort by these organizations to try to clarify the expected direction of upcoming EPA Energy Star for Data Centers program standards, which is scheduled to be finalized in April," writes Julius Neudorfer of North American Access Technologies, in an analysis of the principles. "There were some earlier meetings in September and November of 2009 by the EPA working group that were somewhat ambiguous about which metric was going to be used for the certification process and where and how the measurements were going to be taken."
The EPA indicated last spring that it would use PUE as the basis for its facility-level Energy Star for Data Centers standard. The group previously introduced Energy Star ratings on the efficiency of enterprise servers.
The Green Grid has not discussed the meeting or the resulting guidance on PUE, even as the group did media outreach to publicize the Third Annual Green Grid Technical Forum, which continues today in San Jose, Calif. "Unfortunately the agreement is so new that we haven’t been able to issue a formal agreement around it and/or proactively discuss it," wrote Green Grid spokesperson Lauren Warthan, who confirmed that summary from ICF was accurate. Warthan said the Green Grid may "weave the news" into today's sessions at its technical forum.
But Green Grid board members, in a general discussion of the industry's progress, say that collaboration between major stakeholders has yielded results.
"I think there's a dramatic change from a year ago, when the industry was fragmented," said Christian Belady of Microsoft. "All these organizations are starting to speak the same language and work together effectively. All the pieces are falling into place. PUE was a first step to test the industry and see if it could come together around metrics like PUE. I think that's happened."
The eight groups have formed a task force to further refine these metrics and to identify a roadmap for the future, which is likely to include IT productivity measures and carbon accounting.
"One of the things everyone is driving for is the productivity area," said Belady. "That's the next step."