Task Force Updates Guidance on Measuring PUE

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Data center industry groups continue their effort to improve the way end users use metrics to track the energy efficiency of their facilities. Today The Green Grid and The Data Center Metrics Coordination Taskforce published updated recommendations for energy efficiency measurement and reporting using Power Usage Effectiveness (PUE).

The new report, titled “Recommendations for Measuring and Reporting Overall Data Center Efficiency: Version 2 – Measuring PUE at Data Centers” completes the guidelines for applying the PUE metric promoted by The Green Grid. The report includes specific recommendations for how to measure and calculate PUE in mixed-use data center facilities and introduces a condenser water source energy weighting factor. It also discusses issues with PUE measurement for data centers using on-site power generation or recycling waste heat.

Consortium of Industry Organizations

The report represents the collective work of a task force representing 7×24 Exchange, ASHRAE, The Green Grid, Silicon Valley Leadership Group, U.S. Department of Energy Save Energy Now Program, U.S. Environmental Protection Agency’s ENERGY STAR Program, United States Green Building Council, and Uptime Institute.

PUE  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. As PUE has become a widely-used standard, there’s been active discussion within the industry about differences in how and where energy measurements are taken. The task force report addresses some of these concerns.

“Alignment on these methodologies across the industry will lead to consistent and repeatable measurement strategies that allow data center operators to monitor and improve the energy efficiency when operating their existing data centers, or when designing new facilities,” The Green Grid said in its announcement of the new report.

Four Categories of PUE Measurement

The task force therefore recommends four categories of measurement, which represent a subset of The Green Grid’s measurement methods. These categories range from relatively simple measurements that provide a performance snapshot to more sophisticated measurement means that provide highly detailed performance data.

The task force agreed on the following principles:

  • When calculating PUE, IT energy consumption should, at a minimum, be measured at the output of the uninterruptible power supply (UPS). However, the industry will continue to improve measurement capabilities so that measurement of IT energy consumption directly at the IT load (e.g., servers, storage, network, etc.) 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 mixed-use data centers, the total energy will be all energy required to operate the data center, similar to a dedicated data center, and should include cooling, lighting, and support infrastructure for the data center operations.

“The task force has accomplished a tremendous amount of work to help the data center industry have a common understanding of energy efficiency metrics to improve data center efficiencies and reduce energy use,” said Dan Azevedo, Symantec representative and Board member of The Green Grid. “We are looking forward to working with our colleagues on the next steps for the industry, including identifying a roadmap for future efficiency programs such as IT productivity and carbon accounting.”heir PUE.

About the Author

Rich Miller is the founder and editor at large of Data Center Knowledge, and has been reporting on the data center sector since 2000. He has tracked the growing impact of high-density computing on the power and cooling of data centers, and the resulting push for improved energy efficiency in these facilities.

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