PuE recommendations completed - by Doug Mohney

Views and Opinions on Green IT (May 19 2011)

1. 

   The Green Grid Association and The Data Center Metrics Coordination Task Force have released the latest and greatest recommendations for energy efficiency measurement and reporting. The “Recommendations for Measuring and Reporting Overall Data Center Efficiency, Version 2 – Measuring PUE at Data Centers” completes the guidelines for applying Power Usage Effectiveness (PUE), with specific recommendations on how to measure and calculate PUE in mixed-use data center facilities.  It also throws in a condenser water source energy “weighting factor.”

   PUE is one of the fundamental benchmarks floating around today to measure green-ness, determining the amount of energy used by a data center and the IT gear inside. Of late, it’s become like MIPS (does anyone every remember MIPS out there), with numbers being generated with no standard frame of reference.  So comparing PUEs between data centers was an effectively meaningless exercise.

   Version 2.0 of PUE prefers calculations using source energy consumption, with measurements taken at a minimum at the output of the UPS.  However, improvements in measuring capabilities are expected, ultimately pulling IT energy consumption directly at the source, be it a server, storage, or network devices.

   For dedicated data centers, total energy in the PUE calculation will include all energy sources at the point of utility handoff to the data center owner or operator.  In a mixed-use data center, the total energy will include all energy required to operate the facility, and is expected to include cooling, lighting, and support infrastructure for data center operations.

   Green Grid is by no means done with establishing measurement benchmarks.  In the future, the organization expects to put together a roadmap for future efficiency programs, such as IT productivity and carbon usage; there are already released (and trademarked) metrics for Carbon Usage Effectiveness (CUE) and Water Usage Effectiveness (WUE) for use with helping data center operators review the sustainability of their data centers.

   Is PUE now a “better” standard? I don’t honestly don’t know, but it will be interesting to see how quickly operators update their PUE 1.0 numbers to PUE 2.0 calculations. Given some of the, shall we say, unintended consequences with builders working for LEED certification, it wouldn’t surprise me if PUE 2.0 drifts back into the realm of lies, damned lies, and statistics games marketing people love so very well.

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