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.

Could your data center operate if it lost its water supply? Water is crucial to the operation of many data centers. This summer’s heat wave in much of the U.S. has taxed the water infrastructure in many areas, causing a jump in water main breaks due to the combination of dry round and increased usage.

One of the areas experiencing this scenario is San Antonio, where the local utility has had staff working overtime to address water main breaks. When the area’s clay-based soil here dries out, it contracts and puts a twisting pressure on the mains, according to the San Antonio Water System. If there’s any weakness in the mains, they can rupture.

One of those water main breaks resulted in a cooling challenge for hosting provider Peer 1, one of many data center operators with facilities in San Antonio. On August 7, Peer 1 lost its primary water supply due to a broken water main, creating a “critical situation” for its cooling ssytem.

“Half of our CRAC units are non-functional because of water loss,” Peer 1 reported on its customer forum. “The San Antonio utility has told us a water main break is the cause of the water failure. At this point temperatures in the DC are slowly rising. We are currently deploying temporary A/C units to restore normal temperatures. If temperatures continue to rise we may have to start shutting servers down to prevent damage to the equipment.”

Fortunately, utility service was restored within 45 minutes, and Peer 1 was able to restore cooling within the data center.

What are the challenges and possible responses in water main breaks? Share your thoughts and experience in the comments.

Modern data center power monitoring systems look nothing like the basic electricity meters from which they evolved. Today’s systems comprise sophisticated metering devices, communication networks and software. This brief white paper from Schneider Electric looks at the evolution of the data center monitoring systems and outlines several key guidelines for deployment.

By their nature, mission critical facilities such as Internet data centers are prime candidates for power monitoring systems. By employing monitoring systems to analyze system-wide historical and real-time power data, facility managers can reduce the cost of electricity and improve its quality and reliability.

Where high accuracy metering, disturbance recording, transient detection or harmonic analysis is needed, there is no substitute for power monitors. So if you’re going to deploy power monitors in a data center, this paper offers several key guidelines to keep in mind.

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.



With any popular movie, there is usually a sequel. It looks like the rise in popularity of the Power Usage Effectiveness (PUE) metric has followed the same path. PUE has clearly become the most popularly quoted data center metric lately, perhaps in some cases if only as misguided marketing tool.

On May 17th the Data Center Efficiency Task Force issued a 14 page document entitled “Recommendations for Measuring and Reporting Version 2 – Measuring PUE for Data Centers”  – also known as PUE 2.

While PUE was originally created by The Green Grid in 2008, it was adopted in early 2010 by the Data Center Efficiency Task Force, a group consisting of 7×24 Exchange, ASHRAE, Silicon Valley Leadership Group, the U.S. Department of Energy’s Save Energy Now Program, the U.S. Environmental Protection Agency’s ENERGY STAR Program, United States Green Building Council, Uptime Institute and The Green Grid.

We’ll hear thoughts from members of the task force shortly. But first, let’s take a look at what’s new.

The updated PUE version is meant to clarify and reiterate the updated measurement requirements of the PUE metric and presumably prevent “PUE envy.” It reflects and reiterates the “Harmonizing Global Metrics for Data Center Energy Efficiency” definition of PUE which was released by the task force in February of this year.

Energy Rather Than Power

While it is still called PUE, it now specifies energy usage (expressed in KWH) not power (KW) as the primary basis for the metric. This still seems to be one of the sources of confusion to those using and quoting PUE numbers for their data centers.

There are four PUE measurement categories (0-3), of which three upper categories (1-3) specify annualized energy consumption as the basis for the calculations. Even PUE Category 0, which still allows power demand expressed in KW, now requires that the calculation be based on the highest power used by the facility, not just the lowest power measurement taken on a cold night when the chillers are off.

“PUE Category 0: This is a demand based calculation representing the peak load during a 12-month measurement period.”

This should help level the playing field of some seemingly exaggerated PUE claims.

Guidance on Measurement

The PUE 2 document is an enhancement and continues to follow the “3 Guiding Principles” and the “Harmonizing Global Metrics” document issued in February by The Green Grid and the Task Force and also adopted by some international organizations.
Moreover, PUE 2 includes more details on how to properly measure and calculate PUE for data centers located in a mixed use building, in particular building-supplied chilled water or condenser water.

One of the significant changes in PUE 2 which may be easy to overlook, is the following caveat regarding the requirement to reference the PUE category when proclaiming a data center’s efficiency.

“When publishing PUE, the category must clearly be indicated using a subscript e.g. PUE0, PUE1, PUE2, PUE3. A PUE reported without the subscript is not considered to be in compliance with these recommendations.”

It would seem that very few (if any) of those who have previously made public proclamations of their PUE results have indicated which PUE category methodology and protocols they used to derive their claimed results. Going forward they will hopefully include the category in future PUE announcements. It should be interesting to see how many organizations will adhere to this requirement in any new crop of PUE announcements.