DOE issues energy-efficiency metrics for data centers

energy1Washington, D.C. — The U.S. Department of Energy (DOE), together with the Environmental Protection Agency (EPA) and industry leaders, have agreed on energy-efficiency measurements, metrics, and reporting guidelines for data-center facilities.

There has been no standard approach for key questions as how to measure energy usage, where to take the measurements, and how frequently to do the measuring, says the DOE. As a result, data center operators have difficulty identifying energy usage problems as well as potential solutions.

The new agreement provides guidelines for data center operators to gauge energy use and create opportunities for improved energy performance as well as supports the DOE’s broader goal of reducing industrial energy intensity 25 percent over the next 10 years.

Organizations that collaborated in the effort include the 7×24 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.

Here are the three guiding principles:

  • 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 plans to address IT productivity and carbon accounting in the future.