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PUE Still Above 2.0 for Most Data Centers

A 2010 version of this post was titled "No One Can Agree on Typical PUE". I wrote, "As more data centers measure their PUE, more and more ask what is typical? The industry does not seem to agree, so a wide range of numbers are out there." I updated the post in 2012 with the latest data, concluding that most data centers still appear to be operating above a PUE of 2.0."

I put the question to Vertatique's global Green ICT community in August 2013 via a tweet: "After years of #GreenICT, is there evidence that most #datacenters now operate below PUE 2.0?". This was one of our most-retweeted, but no one came forward with new evidence. Some replied in the emphatic negative. Here is the 2012 analysis, which still stands.

Let's use the PUE values the EPA in 2007 predicted for four 2011 target scenarios to see where the United states is now, as well as look at a survey that compares three world regions.

Today's 'mega data centers' are striving for very low PUEs by combining "Best Practices" and "State-of-the-Art" with the advantages of scale. Some are even below 1.1 PUE. Mega data centers represent the pinnacle of energy efficiency.

Scenario PUE
Current Trends 1.9
Improved Operations 1.7
Best Practices 1.3
State-of-the-Art 1.2

EPA Estimates in 2007 for PUE Values in 2011

Some findings seem to indicate most data centers are at least at the predicted 1.9 PUE based on 2007's "Current Trends", but I am skeptical.

EPA's ENERGY STAR® for Data Centers rating system is based on a mean PUE of 1.9. The EPA will not publish the names of the 61 data centers in the 2010 ENERGY STAR reference set and we suspect that it is skewed by some of those mega data centers.

The Uptime Institute 2012 Data Center Survey PUE finding has a similar problem with large data center skewing. "Average PUE of respondents’ largest datacenter is between 1.8 and 1.89." Adding in the survey participant's smaller data centers would like increase average PUE.

The EPA group responsible for ENERGY STAR for Servers implies in its estimates of energy and CO2e savings that a PUE of 2.5 is more typical. Capgemini in 2010 used 2.5 to describe an "average datacenter". ""

Digital Realty Trust's 2012 data center survey reports:

  • North America - "Few (7%) don’t know their PUE and even fewer (4%) are unfamiliar with PUE. One in five (19%) reports a PUE of less than 2.0. The average reported PUE is 2.8."
  • Europe - "One in twelve (8%) is unfamiliar with the term PUE. One in eight (12%) doesn’t know their PUE, compared with 18% in the last wave.The average reported PUE is 2.61. Nearly one in four (23%) reports a PUE of 3 or more and 28% report a PUE below 2.0."
  • Asia Pacific - "One in nine is unfamiliar with PUE and a similar number doesn’t know their PUE. The average reported PUE is 2.52. One in five (18%) reports a PUE of 3 or more. One in three (31%) reports a PUE below 2.0." This results are from only three locations: Australia, Hong Kong and Singapore. Full participation by India and China would likely significantly alter these results.

We are confident our new headline is accurate. Most data centers have not fully implemented "Best Practices" or "State of the Art" and are still well above 2.0 PUE. The only upside is that cloud computing may be improving industry PUE by moving more computing to state-of-the-art mega datacentrs.


How can data center operators not know their PUE? This report would be a gold mine of leads for Green IT Consultants.

State of the Art

Good article!
I'd say that actually state of the art are data centres that have got down to sub 1.2 PUE.
I've visited a facility recently that was 1.12 - 1.14, now that's efficient!

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