Four years ago, the U.S. Environmental Protection Agency set off alarm bells in Congress with a report on the rapid growth in electricity use by data centers in the United States.  Although starting from a relatively small portion of total power consumed each year, data centers’ appetites for electricity appeared to grow by over 14 percent each year beginning in 2000, and were projected to continue at that pace – doubling between 2006 and 2011.

Now a study from Stanford University Consulting Profession Jonathan Koomey says that the trend of increased power use is not nearly as pronounced as EPA projected, and the reasons have less to do with energy efficiency efforts promoted by the agency than with the economic recession we’ve all been experiencing.  

There are several reasons why electricity use in data centers became such a concern for policy makers.  First of all, the development of these centralized network servers represented one of the sea change shifts in the economy—the shift from a paper-based economy to one increasingly dependent on digital information management in financial services, communications (including the Internet and entertainment), and for maintaining health care records and management systems. 

Under the projections documented by EPA, data centers by 2006 were already consuming up to 1.5 percent of all the power used in the country.  According to the report this was “more than the electricity consumed by the nation’s color television sets” and equal to annual power used by nearly 6 million U.S. households. 

The government had a secondary interest; its own reliance on data centers was growing rapidly as a result of regulations requiring digital retention of public records, digital provision of services, and the increase in use of web sites for disseminating information to the public about agencies and their activities. EPA reported that the federal government alone was responsible for about 10 percent of data center power use in 2006, roughly 6 billion kilowatt-hours annually, and together the federal government was spending $450 million each year.

Under EPA’s projections, a doubling of this load could start amounting to real money.

Additionally, because data servers essentially must run 24/7 they were feared to be contributing not just to overall electricity demand, but also they could not exhibit the flexibility to reduce operations during peak summer periods of high power demand.  With record breaking temperatures and historic utility system peaks being set across the nation this year, the concern was that our reliance on digital data was running counter to our ability to maintain the sensitive networks that data centers manage.

The report spurred a great deal of consternation among environmental groups worried about the carbon footprints of industry. And it created a kind of cottage industry among consultants and academics – not to mention monitoring equipment vendors – to promote numerous efficiency opportunities that would stem the expected tide of increased power consumption.

And the opportunities are many.  EPA’s report pointed to a wide variety of measures that could be implemented to improve efficiency and energy productivity.   

One of the biggest factors in power use by servers is the need for cooling and ventilation, and some experts believe that up to half of the power used for cooling centers is completely wasted – by design.  Improving temperature monitoring and ventilation is a major source of efficiency.

But the other power use is the basic need for juice to run the server and network infrastructure.

One of the key efficiencies opportunities recognized by EPA was for increase “virtualization” of servers.  Virtualization, defined as “the masking of server resources, including the number and identity of individual physical servers, processors, and operating systems, from server users,” is a way of having a smaller number of servers perform more work by combining what would otherwise be done by multiple servers.

In various surveys of data center managers seeking efficiency gains, server virtualization was usually identified as the number one short-term strategy for conserving power. 

So among the major surprises of Professor Koomey’s study is that electricity use in the U.S. data centers did not double between 2005 and 2010, as projected by EPA, but rose just 36 percent. And that the main reason for less power consumption at data centers was not the drive for “greening” servers or more efficient operations, but the simple fact that the recession meant there were fewer servers being installed across the country. 

Also part of this situation was the trend towards “cloud computing” resulting in larger, more centralized servers and national networks that were displacing the need of individual companies or agencies to build and host their own data centers.

The increased installation of “volume servers” was in itself a productivity measure, Koomey suggests, as this contributes to a much lower average amount of power required by data centers, rather than the strong average growth projected by the EPA report.

In summary, Koomey concluded that electricity used by U.S. data centers was significantly less than what EPA had told Congress it would be, and the results “were driven mainly by a lower server installed base than was earlier predicted rather than the efficiency improvements anticipated in the report to Congress.”

The new study in no way lessens the importance of energy efficiency or the need to constantly seek technology and operational improvements to get the most out of our systems.

It does, however, point out the fact that we cannot always predict the future, so we need to constantly be readjusting our expectations in line with reality as it develops.

Read the reports:

EPA Data Center Report to Congress 2007

 Jonathan Koomey: Growth in Data Center Electricity Use 2005-2010

 GreenGridDataCenter2010.pdf

Arthur O’Donnell is The Energy Overseer, an independent journalist and industry analyst who documents the constantly changing field of energy policy and regulation.  Look for his blogs on EcoCloud and at www.energyoverseer.com.