Google's PUE Numbers Slip Slightly
Many companies have released information about their data center energy effiency using the Power Usage Effectiveness (PUE) metric. But none have received more scrutiny than Google, whose exceptional PUE numbers have been widely discussed in the data center industry. The latest data from Google show that the company’s numbers can go up as well as down.
Google’s quarterly energy-weighted average PUE rose to 1.20 in the second quarter, up from 1.19 in the the first quarter of 2009. The best-performing facility had a PUE of 1.15 for the quarter, compared to 1.11 for the most efficient site in Q1.
What’s behind the increase, which followed two quarters of improvement? Three new Google data centers met the inclusion criteria for the company’s public PUE reporting, expanding the number of facilities to nine.
“The PUE of the new facilities is elevated due to commissioning and bring-up activities,” Google said. “The combined impact of partially-commissioned facilities and traditional seasonal effects resulted in a (quarter-on-quarter) increase of our quarterly energy-weighted average PUE, bringing it to 1.20. ”
The latest report reinforces the value of efficiency reporting over time to track seasonal fluctuations and changes in a company’s data center environment. In response to industry questions about its disclosures, Google has made several presentations at industry events providing details about its efficiency strategies and how it measures and calculates its PUE. The company will continue to provide public updates on its data center energy efficiency on a quarterly basis.
Dave ClarkPosted July 20th, 2009
These recent increases in PUE may be due to fewer free cooling hours as the weather warms up in the Northern Hemisphere. Most of the graphs of PUE over time that I’ve seen include seasonal variation – the PUE get’s better in the in winter and worse in the summer, even if the long term trend is lower. Data Centers with low PUE metrics would tend to be especially sensitive to the addition of any mechanical cooling and the associated increase in Total Facility Power.
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