Grow a Greener Data Center

What are the most important factors to consider when deciding what hardware to use to enable various IT services? Processing speed? Storage capacity? Purchase price? The presence of certain functionality?

An element that should be among the top evaluation criteria yet is often overlooked is energy efficiency. That single characteristic, multiplied by the thousands of pieces of hardware operating around the clock in a typical corporate Data Center has a significant impact upon company costs, environmental impact and even productivity.

Hardware Costs

Data Centers consume massive amounts of energy, operating around the clock to power and cool servers, storage frames and networking devices that in turn enable critical business functions including online customer transactions, financial data storage, electronic communications and more. No surprise, then, that energy consumption is the largest operational expense of any Data Center. A facility of moderate size and capacity can easily accrue hundreds of thousands of dollars per year in energy bills. The U.S. Environmental Protection Agency reported in 2007 that Data Centers in the United States alone used 61 billion kilowatt hours (kWh) of energy in 2006 at a cost of $4.5 billion.

Viewed on a smaller scale – several Data Center industry groups now estimate that the power consumed by most servers over their usable life will cost a company more than the purchase price of those machines.

Such energy usage comes with an environmental cost as well as a financial one. Conventional methods for producing electricity consume finite resources (fossil fuels), emit greenhouse gases and pollute the air, so choosing energy efficient IT hardware makes a business greener. It is desirable to be energy efficient in all company operations, but doing so is especially significant in a Data Center because such facilities have a power density 40 times or more that of traditional office space.

Finally, because a company’s Data Centers and the IT hardware they contain enable so many business functions they are directly connected to a company’s productivity. Company growth means greater demand for IT services, which leads to installing more hardware that then consumes greater amounts of a Data Center’s electrical capacity. A growing company must use its Data Center electrical capacity efficiently or it can find itself facing one of two prospects: having productivity suffer by failing to provide all business functions as demand for them increases, or having to spend millions of dollars to build out additional Data Center capacity.

Effective and Simple

Although there are many methods for improving Data Center energy consumption, employing efficient hardware – not only in the choice of individual models but also designing Data Center network and storage systems with an eye toward overall energy efficiency – is one of the most effective and simplest to implement.

It’s effective because IT hardware resides at the end of the delivery chain for Data Center power and cooling. Reducing their power consumption provides a cumulative benefit across that entire chain. If a server draws less power, for instance, that equates to less electricity that has to be conditioned, cooled, distributed, converted and delivered throughout the Data Center. (Research by Emerson Network Power, which manufactures Data Center power and cooling components, indicates that 1 watt of energy savings at the hardware level saves nearly 3 watts overall.)

It’s simple because improvements can be made gradually, as part of the company’s normal cycle for refreshing IT hardware. (Along with ensuring that new systems that are installed into the Data Center are energy-efficient, it’s wise to remove older hardware that is inefficient or poorly utilized.) Unlike performing other major energy improvements to a Data Center facility – replacing a power distribution unit or upgrading the configuration of the cooling system, for instance – the upgrade can be done without major capital cost or potential downtime.

Determining Energy-Efficiency

Many hardware manufacturers can (and should) provide energy efficiency data along with the performance specifications of their products, allowing those who make purchasing decisions to choose systems that meet their computing needs for the foreseeable future while also providing satisfactory performance on a per-watt basis. (Cisco’s own Product Efficiency Calculator at enables users to determine the power usage, electrical efficiency and energy costs of its devices, with information customizable according to the conditions in a customer’s own Data Center.)

Earlier this year, the U.S. Environmental Protection Agency introduced the first in what will be a series of specifications for IT hardware under its Energy Star label, making it easier than ever to identify machines that are energy efficient. The first standard applies to individual servers that include one to four processing slots. To qualify for the designation, a server must meet certain efficiency thresholds, consume minimal power while idle and be capable of providing monitoring data such as inlet air temperature and processor utilization.

Table 1 illustrates the electrical efficiency minimums from the Energy Star Computer Server Specification.

Table 1

A second tier of the standard is scheduled to come out in 2010 and will address systems with more than four sockets, blade servers, fully fault tolerant servers, server appliances and multi-node servers. Separate Energy Star standards for storage devices and networking devices are planned for the future. A copy of the existing standard is available at


Incorporating energy efficiency as a major factor in IT hardware purchasing decisions is a simple but powerful way to reduce operational costs, lower environmental impact and extend the usable life of a company’s Data Centers.

If you have any questions regarding the topics discussed in this article, you can email questions to Kevin from now through October 1, 2009.

About the Author:

Douglas Alger is Cisco’s IT Architect for Physical Infrastructure. He develops architecture roadmaps, solutions and policies for the physical infrastructure of the company’s Data Centers and other critical facilities around the world.

Doug has more than 20 years of varied professional experience including more than 12 years in Data Center physical design, Data Center operations, IT project management, construction project management and IT infrastructure management. He has participated in more than 80 major Data Center projects, from all-new construction to substantially retrofitting existing facilities, and is the author of two Data Center design books, Grow a Greener Data Center and Build the Best Data Center Facility for Your Business.

Doug is a popular speaker, with more than 250 corporate customer engagements and dozens of presentations at various Data Center industry conferences. Prior to joining Cisco, Doug was a writer and editor in the News & Publications office of Syracuse University and, before that, a full-time stringer for the Los Angeles Times. He has a bachelor’s degree in journalism from San Jose State University.

Douglas Alger
Grow A Greener Data Center
By Douglas Alger
ISBN-10: 1-58705-813-8
Published: Aug 17, 2009
US SRP $40.50
Publisher: Cisco Press