The upward trend in the growth of data center energy usage has slowed, according to a new study from Stanford professor Jonathan Koomey. The report found that data center power consumption increased by 36 percent from 2005 to 2010, a much smaller increase than the 100 percent gain projected in an influential study Koomey prepared in 2007.
"The rapid rates of growth in data center electricity use that prevailed from 2000 to 2005 slowed significantly from 2005 to 2010, yielding total electricity use by data centers in 2010 of about 1.3% of all electricity use for the world, and 2% of all electricity use for the US," Koomey writes. The report, "Growth in Data Center Power Use 2005 to 2010,” was prepared for the New York Times, which summarizes the findings. The full report is available via Koomey's web site.
The moderating pace of data center energy use is "driven mainly by a lower server installed base than was earlier predicted rather than the efficiency improvements anticipated in the report to Congress," writes Koomey, whose 2007 report to Congress and the Environmental Protection Agency has framed most subsequent discussions of data center energy usage.
Economic Slowdown and Virtualization Cited
Koomey says companies have been buying fewer servers than anticipated due to the economic slowdown and the benefits of virtualization, which allows users to make better use of their server capacity. The study downplays the potential impact of an industry-wide effort to develop metrics and share best practices on energy efficiency, but indicated that these efforts could begin to have a larger impact in the near future, as more computing workloads shift to cloud computing platforms hosted in cutting-edge facilities.
In compiling the data, Koomey used estimates of installed servers from the research firm IDC. He assumed a data center Power Usage Effectiveness (PUE) rating of between 1.83 and 1.92, based on estimates of the average PUE reported in recent samplings by the EPA Energy Star Program and the Uptime Institute. While some cloud computing data centers have PUEs in the 1.1 to 1.3 range, Koomey noted that less efficient in-house corporate data centers account for the largest number of servers. "That (PUE) assumption will need to be revisited as cloud computing becomes more widely used," he wrote.
Energy Usage Slows During Building Boom
The New York Times has been investigating data center energy use since early 2010, with a particular focus on Google's data centers. "Data centers’ unquenchable thirst for electricity has been slaked by the global recession and by a combination of new power-saving technologies," writes The Times John Markoff. "The decline in use is surprising because data centers, buildings that house racks and racks of computers, have become so central to modern life," "The slowdown in the rate of growth of electricity use is particularly significant because it comes in the midst of the biggest build-out of new data center capacity in the history of the industry."
The five-year period reviewed in the Koomey tracks a time of dynamic growth for the data center industry, in which Google, Yahoo, Microsoft, Facebook and Apple all built enormous cloud data centers, while service providers filled space at wholesale data centers built by Digital Realty Trust and DuPont Fabros Technology.