Green Grid Publishes Final PUE Guidance

The Green Grid has published its second and final volume of guidelines for applying the power usage effectiveness (PUE) metric.

The new report, Recommendations for Measuring and Reporting Overall Data Center Efficiency: Version 2 – Measuring PUE at Data Centers, includes recommendations for how to measure and calculate PUE in mixed-use data center facilities, and introduces a condenser water source energy weighting factor.

PUE determines the amount of energy used by a data center facility and the IT gear inside of it, as a measurement of total energy divided by IT energy consumption.

The new guidance outlines the following principles:

• PUE, using source energy consumption, is the preferred energy efficiency metric for data centers.
• 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 association says that this standard methodology will allow data center operators to come up with consistent and repeatable strategies to monitor and improve energy efficiency.

Organizations involved in preparing the latest report include the 7x24 Exchange, ASHRAE, Silicon Valley Leadership Group, the Department of Energy’s Save Energy Now and Federal Energy Management programs, the Environmental Protection Agency’s Energy Star program, U.S. Green Building Council, and Uptime Institute.

“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.”

Last December the Green Grid announced additional metrics to complement PUE, including Carbon Usage Effectiveness (CUE) and Water Usage Effectiveness (WUE). These are all designed to help data center operators assess the sustainability of their data centers.