Efficiency standards for US computers

The U.S. Department of Energy has announced that it wants to establish minimum energy efficiency standards for all computers and servers sold in the United States. A new study shows that large server farms can, in fact, cut electricity use and greenhouse gas emissions sharply with off-the-shelf equipment and proven energy management practices.

Most big data centers could slash their greenhouse gas emissions by 88 percent by switching to efficient, off-the-shelf equipment and improving energy management, according to new research.

The carbon emissions generated by a search on Google or a post on Facebook are related mostly to three things: the computing efficiency of IT (information technology) data center equipment, like servers, storage and network switches; the amount of electricity a data center's building uses for things other than computing, primarily cooling; and how much of the center's electricity comes from renewable or low-carbon sources

"Of these three, improving the efficiency of the IT devices is overwhelmingly the most important," said Jonathan Koomey, a co-author of the study, "Characteristics of Low-Carbon Data Centers," published online June 25 in Nature Climate Change.

The processors in most server farms perform computations at just 3 percent to 5 percent of their maximum capacity. Server virtualization, consolidation and better software can increase utilization to greater than 30 percent, and in some cases to be as high as 80 percent.

Big, outward-facing companies whose business primarily is cloud computing have solved the sustainability problem for data centers. eBay even discloses its data center efficiency publicly at dse.ebay.com.

After IT equipment, the second major way to reduce greenhouse gas emissions associated with data centers is to improve the efficiency of the buildings that support them. A key measurement of efficiency is the ratio of electricity used to perform computations to the amount of power consumed for secondary support, like cooling and monitoring systems. Typically that ratio is about 1 kilowatt-hour for computing to 0.8 kWh for the facility. State-of-the-art data centers have reduced the ratio to about 1 to 0.1 kWh, said study co-author Arman Shehabi of Lawrence Berkeley National Laboratory's Environmental Energy Technologies Division. "They locate server farms in cool climates like the U.S. Northwest, Sweden and Iceland. They purchase processors that are less sensitive to heat. And they use efficient cooling equipment and air-flow management."

Of the potential 88 percent reduction in greenhouse gas emissions, though, IT device efficiency accounts for about 80 percent and facility energy management for only about 8 percent. Once those two areas are maximized, sourcing electricity from renewables like wind and solar power, plus green handling of retired equipment, can get a typical data center's emissions down 98 percent.