DOE Guides Data Centers in Standardizing Their Energy Efficiency Metrics

February 22, 2010 by Jeff Shepard

The U.S. Department of Energy (DOE) joined with the Environmental Protection Agency (EPA) and industry leaders to announce what is described as a breakthrough agreement on energy efficiency measurements, metrics, and reporting conventions for data center facilities. As data center usage continues to escalate and energy costs rise, energy efficiency has become a growing concern for data center owners and operators. There has been no standard approach for such key questions as how to measure energy usage, where to take the measurements, and how frequently to do the measuring. As a result, data center operators have difficulty identifying energy usage problems as well as potential solutions.

The new agreement provides guiding principles for data center operators to gauge energy use and create opportunities for improved energy performance. By providing clear direction for data center energy management, the groups participating in the agreement hope to spur data center operators to improve their measurement practices leading to higher efficiency and reduced energy consumption.

Given the rapidly increasing number of data centers nationwide and the steady growth in size and corresponding electricity demand of individual data centers throughout our economy, improving the energy efficiency in data centers is an important part of reducing overall energy use in the Information and Communications Technology sectors. The progress made in this agreement will also support the Department of Energy’s broader goal of reducing industrial energy intensity 25% over the next 10 years.

Organizations that collaborated in the effort to develop these guiding principles include the 7x24 Exchange, ASHRAE, The Green Grid, Silicon Valley Leadership Group, DOE’s Save Energy Now and Federal Energy Management Programs, the U.S. Environmental Protection Agency’s ENERGY STAR® Program, the United States Green Building Council, and the Uptime Institute.

The guiding principles include:

– 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 cooling, lighting, and support infrastructure for the data center operations.

A task force 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.