How to Keep Energy Score

Julius Neudorfer
According to an announcement issued by the consulting firm ICF international on behalf of the U.S. Environmental Protection Agency, a group consisting of eight leading organizations that set or use data center energy efficiency metrics met in Washington, D.C., this past Jan. 13. The outcome of that meeting has been described as follows:

'The outcome of the meeting is an agreement to three guiding principles for measuring energy efficiency in data centers at the present time. These guiding principles are 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. Each of the participating organizations has agreed to promote these guiding principals to their members and stakeholders in an effort to bring uniformity to the measurement of data center energy efficiency, while the dialogue continues to advance existing metrics. "

The organizations represented were the 7x24 Exchange, ASHRAE, The Green Grid, Silicon Valley Leadership Group, U.S. Department of Energy's Save Energy Now and Federal Energy Management Programs, U.S. Environmental Protection Agency's ENERGY STAR Program, U.S. Green Building Council, and Uptime Institute.

The three guiding principles are:

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 or 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 announcement further stated:

'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. Member organizations are committed to applying and promoting these guidelines to their programs.

A task force, consisting of the organizations listed below, has been created to further refine these metrics and to identify a roadmap for the future. The group also aspires to address IT productivity and carbon accounting in the future.

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. 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.

There is still some ambiguity in this new announcement since they seem to be using the term PUE (Power Usage Effectiveness) yet also using the word 'energy."  (Energy is power over time, i.e., KW vs KWH.)

Nonetheless, I believe that 2010 will bring about a large increase in data center energy efficiency awareness and prompt many organizations to start implementing some form of energy monitoring and management. The underlying issue, is that in many cases (as the EPA study found), very few data centers have any form of energy monitoring for the IT load, other than the output of the UPS, and even fewer have input power measurement capabilities, other than the monthly utility bill.

So attention all manufacturers of energy monitoring systems -- start your sales force.

Add Comment      Leave a comment on this blog post
Feb 4, 2010 12:02 AM Dennis Kniery Dennis Kniery  says:
Julius, Thanks for posting the summary so we can have a brief explaing where things stand as of now. It is most difficult to get a condensed understanding of progress to date. I believe we are about to get into trouble with the goverment setting PUE standards (I heard they were pushing for 1.4) without fully understanding the mesurement. I look forward to seeing how Energy Star will work as it will allow us to have a public forum for comparison currently not available. Your recommendation or at least acknowledgement of the lack of tracking instrumentation being a key issue is certainly valid. I find the PUE calculation misleading if I can put cabinet fans on the server UPS and if they run at full speed independent of need, the PUE improves. One can only hope that we gain more maturity as an industry before we are legislated into reaction. Reply
Feb 5, 2010 8:02 PM Infrarati Infrarati  says:
Julius, thx for the summary. Nice that we have the PUE metric but at the end it is only a formulae. To have proper energy measurements, in my opinion, we must have a Power Usage Monitoring Architecture Framework. For designing an efficient power usage monitoring framework, it is important to assemble a coherent system of functional building blocks or service components. In that way you can enforce standard measurements. In my blog I made a sketch for such a framework. Reply
Nov 9, 2012 11:46 AM Karl Smith Karl Smith  says:
I'm pleased to see that at least there's an effort on measuring and improving the energy consumption. Procedures most be implemented and information on green IT spread. Costs can be diminished through green datacenters A. And also costs on power usage Reply

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