We all know data centers draw a lot of power. But what standard or standards should be used in measuring its efficiency? Well, a group of leaders from across the industry got together in January to agree on data center energy efficiency measurements, metrics and reporting conventions.
Organizations represented were the 7×24 Exchange, ASHRAE, The Green Grid, Silicon Valley Leadership Group, U.S. Department of Energy’s SaveEnergyNow and Federal Energy Management Programs, U.S. Environmental Protection Agency’s ENERGY STAR Program, U.S. Green Building Council, and Uptime Institute.
The following guiding principles were agreed to:
- 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 IT energy, cooling, lighting, and support infrastructure for the data center operations.
This guidance is meant to help the industry have a common understanding of energy efficiency metrics that can generate dialogue to improve data center efficiencies and reduce energy consumption.
The organizations will continue to work as a task force 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.