Uptime Institute: The Average PUE is 1.8

The average Power Usage Effectiveness (PUE) rating for data centers is 1.8, according to a survey of more than 500 data centers conducted by The Uptime Institute. PUE has become the leading metric for tracking the energy efficiency of data centers.

The average PUE has been a subject of some debate in the industry. The Uptime Institute, which tracks the operations of a group of enterprise data centers, has previously said that the average PUE was around 2.5. Others cite an average of 2.0, and the EPA’s Energy Star program reported a 1.91 average PUE in 2009 data it collected more than 100 data centers.

Some Signs of Improvement

The latest data, announced today during the kickoff of The Uptime Institute Symposium 2011 in Santa Clara, Calif., suggests some improvement in overall energy efficiency for the data center industry, particularly compared to some of Uptime's earlier estimates.

But there's still plenty of room for improvement. Eighteen percent of the survey respondents said they did not know the PUE of their data centers.

The PUE metric championed by The Green Grid 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. Large users such as Google, Yahoo, Facebook and Microsoft have reported industry-leading ratings in the 1.07 to 1.2 range. These numbers demonstrate the potential for ultra-efficient data centers, but are sometimes critiqued as having limited relevance for enterprise data centers that must engineer their facilities for many types of applications and workloads.

Establishing the average PUE could be helpful to end users in comparing claims of energy improvement from vendors, who often note a percentage improvement in energy usage, usually when compared to an "average" PUE, which is often 2.0 or higher. Using a higher average yields a larger "percentage gain" for the product.