Chapter 1: Going Green in the Data Center

Cisco Press

Cover image 

Excerpt from Grow a Greener Data Center.

By Douglas Alger

Published by Cisco Press

ISBN-10: 1-58705-813-8

ISBN-13: 978-1-58705-813-4

This chapter defines green, discusses the drivers for companies to build greener Data Centers, and presents the benefits a business can see from environmentally friendlier server environments. The chapter also outlines incentive programs that reward green efforts and recaps environmental activities that several major companies pursue today.

Defining Green

If you’re reading this book, you’re obviously interested in having the server environments that house your company’s computing equipment be green. What exactly does the term green mean, though, as it relates to a Data Center facility and Data Center operations?

Does a green Data Center mean a facility that was constructed using fewer natural resources? Does a green Data Center mean a hosting space that produces fewer pollutants? Does a green Data Center mean a room that consumes less energy? Conceivably the term means all those things and more.

No single definition has been adopted across the Data Center industry for what constitutes a green Data Center. There are, however, generally accepted concepts from the greater building industry that are relevant to consider.

The term green building is defined as designing a building so that it uses resources—energy, water, and materials—more efficiently and has less impact upon people and the environment. Substitute Data Center for building and you have

Green Data Center:  A computing environment that uses resources in a more efficient manner and has less impact upon people and the environment.

Another relevant building industry term is sustainable development, which is defined as development that uses natural resources in such a way as to meet people’s needs indefinitely. Or as stated by the World Commission on Environmental Development that first coined the term in a 1987 report to the United Nations General Assembly, “meeting the needs of the present without compromising the ability of future generations to meet their own needs.”

Truly sustainable commercial buildings are extremely rare. Although you likely won’t achieve 100 percent sustainability for your Data Center facility, it’s useful to keep the ideals in mind as you make design and management decisions concerning the facility. Even achieving a Data Center that is mostly sustainable is a major step forward from past server room designs and can provide significant benefits to your company.

The Reasons to Go Green

A company that is sensitive to the environment and demonstrates that sensitivity through its actions shows admirable social consciousness. In the competitive marketplace that many businesses function in, however, the simple desire to “do the right thing” isn’t enough to enact green practices. Going green must be evaluated for its impact upon the company, particularly the company’s bottom line.

Going green with a Data Center requires even more scrutiny because of the critical role the facility serves in enabling the business to function. Relevant factors when considering a green Data Center include the following:

  • Trade-offs in functionality and availability: Does a green Data Center have more or less capacity (that is, power, cooling, connectivity) than other server environments? Are its physical infrastructure components more or less susceptible to downtime?

  • Cost implications: Is a green Data Center more or less expensive to build than a facility that doesn’t bother with environmental considerations? Is it more or less expensive to operate? Is there enough return on investment that retrofitting an existing facility to be greener is worthwhile?

  • Use of technologies uncommon to the Data Center industry: What operational changes or new expertise does a green Data Center require?

  • Ancillary issues: Data Centers aren’t islands. They are a key piece of how a company functions. What issues outside of the hosting space are influenced by having a green Data Center?

With these issues in mind, then, what are the merits of designing a new Data Center to be green or retrofitting an existing one? The following sections answer this question.

Growing Power Demand, Shrinking Availability

Data Centers as a group consume a staggering amount of power and their appetite is growing. An August 2007 report by the United States Environmental Protection Agency estimates that U.S. Data Center power usage doubled in 6 years, consuming 61 billion kilowatt hours (kWh) of energy by 2006. The report additionally projects that, unless Data Centers make efficiency improvements to both facilities and IT (Information Technology) components, that power consumption will reach 100 billion kWh by 2011. The European Commission, meanwhile, in the written introduction to its Code of Conduct on Data Centers (discussed elsewhere in this chapter) estimates Western European Data Center consumption at 56 billion kWh per year in 2007, reaching 104 billion kWh by 2020.

Figure 1.1 illustrates U.S. Data Center power consumption between 2000 and 2011, according to the U.S. Environmental Protection Agency. You can find a copy of the report, “Report to Congress on Server and Data Center Energy Efficiency,” at the EPA website: http://www.energystar.gov/index.cfm?c=prod_development.server_efficiency_study.

Figure 1.1

Estimated U.S. Data Center Power Consumption Trend

Such dramatic growth in consumption can be attributed in part to the overall proliferation of technology and Internet usage throughout society. More emails, instant messages, web searches, online financial transactions, and video downloads occur today than just a few years ago. More servers, networking gear, and storage devices are needed to facilitate that burgeoning Internet traffic—more in quantity, more in performance, and therefore more in power consumption.

Also, at many companies, Data Center power and cooling capacity are seen as unlimited resources, so few barriers exist to inhibit demand. If you allocate a budget each fiscal quarter to buy servers and there are no restrictions, why not buy the fastest machines with the most processing capability you can afford? Unfortunately, that top-end performance often translates to top-end power demand and heat production.

Another likely contributing factor is the shrinking form factor of Data Center equipment. Today’s server models are physically smaller than yesterday’s, allowing more of them to be placed in each Data Center cabinet than in years past. Even if a new machine consumes less energy than its predecessors, and not all do, the fact that you can install more equipment in the same physical space means that more overall power is consumed.


Note - My personal lesson as to how small-profile servers can increase the demand for Data Center resources came in 2004 when one Cisco business unit chose to deploy a series of 1U-high boxes.

The initial wave of what would ultimately include more than 200 machines was to be installed into a server row with 12 server cabinet locations. After filling a few 42U-high cabinets close to half-full with servers, the installers determined (thanks to amp-reading power strips) that the servers’ cumulative electrical draw had already exceeded the standard power budget for an entire cabinet, despite taking up less than half the space.

We also realized something else just by standing near the cabinets: the gear was hot. The older room’s 60 watts per square foot (645.8 watts per square meter) of cooling simply wasn’t up to the task of dissipating the heat generated by these higher-performing, tightly packed servers.

Suddenly, interior cabinet space was no longer a true indicator of a Data Center’s maximum capacity. Power and cooling was. (And is....)


Regardless of its cause, such steep growth in electrical demand among Data Centers can’t continue indefinitely. There simply isn’t an infinite number of real estate properties available that are—or can be—equipped with massive amounts of commercial power and well suited overall to house a Data Center. (Well suited meaning located away from environmental hazards, capable of accommodating sufficient floor space, close to a skilled work force, and so on.)

A modern Data Center of significant size, say 20,000 or 30,000 square feet (rounding down for convenience, 2000 or 3000 square meters) and designed with redundant standby electrical infrastructure can easily demand 20 megawatts (MW) of commercial power capacity. More massive installations, if built to house the same equipment density across its larger floor space, need power on a proportional scale. Therefore, a Data Center 10 times as large can conceivably need 10 times the power. As an example, published reports describe a Microsoft Data Center of 500,000 square feet (46,452 square meters) in Northlake, Illinois, having 198 MW of electrical capacity and Data Center space for Digital Realty Trust in Ashburn, Virginia, totaling 432,000 square feet (40,134 square meters)—distributed among three buildings—and having 225 MW of electrical capacity.

Properties readily possessing access to such large supplies of electricity are rare today and will be even less common tomorrow. At some level, everyone in a given region is fishing from the same proverbial pond. Your prospective Data Center competes for power resources with every other new home, office building—and major Data Center—in your area. Whoever builds in the area first, or pays the utility company to reserve the capacity, gets it.

Greening your Data Center, which includes improving the electrical efficiency of both the building and the computing equipment it houses, allows you to get more out of the power capacity of a given property. When executed during the planning phase of a Data Center project, a green design can reduce the power needs of the facility and perhaps even allow it to be built in a location that otherwise could not sustain it. If greening is done to an existing Data Center, the improvements can slow or stop rising electrical demand from outstripping available capacity.

If you don’t build such efficiencies into your Data Center, thereby lowering how much power it consumes, there might come a day when there simply isn’t enough commercial power available locally to run the Data Center at full electrical load.

Figure 1.2 shows U.S. Data Center power consumption trends predicted by the U.S. Environmental Protection Agency, assuming various energy-efficiency measures are implemented. The strategies, which range from IT improvements—such as server and storage consolidation—to facilities improvements—such as airflow optimization and implementing high-efficiency electrical components—are all presented within later chapters of this book.

Figure 1.2

Estimated U.S. Data Center Power Consumption Trend, With Green Measures­

Monetary Benefits

If you have ever built or maintained a Data Center you know they’re expensive. Companies routinely pay more per square foot (meter) to construct hosting areas than any other type of floor space in their buildings due to Data Centers’ extensive physical infrastructure. Add to that the expense of the equipment you must purchase to make the room functional—servers, networking gear, and storage devices—and even a space with a small physical footprint can cost hundreds of thousands of dollars.

Over the lifetime of a Data Center, those initial construction and deployment costs are ultimately dwarfed by the room’s operational expenses, led first and foremost by its power bills. The 61 billion kWh of annual energy that the EPA estimated for U.S. Data Centers in 2000 carried a price tag of $4.5 billion per year, for example; the 100 billion kWh estimated for 2011 will carry a cost of $7.4 billion.

Applying green materials and practices to a Data Center typically involves an increase in capital expenses—the initial cost for physical construction or deploying components—and then a decrease in operational costs. Because the capital cost is a one-time expenditure whereas the operational savings continue for years, most Data Center green improvements ultimately provide significant cost savings over time.

How significant? A cost-benefit analysis of 33 green building projects concluded that a 2 percent increase in upfront costs typically results in 20 percent savings over the life of the building—a tenfold return. The financial benefits included lower energy, waste disposal and water costs, lower environmental and emissions costs, lower operations and maintenance costs, and savings from improved employee productivity and health.

The study, The Costs and Financial Benefits of Green Buildings, was developed by clean energy industry consulting firm Capital E for California’s Sustainable Building Task Force and reviewed 25 office buildings and 8 school buildings completed, or scheduled for completion, between 1995 and 2004.

“The findings of this report point to a clear conclusion: building green is cost-effective and makes financial sense today,” wrote the study’s authors.

Table 1.1 shows the cost premiums and savings that green buildings incur compared to conventional construction, according to the study.

The data in Table 1.1 came from green building projects, not green Data Center projects, so costs and savings will differ for a server environment. For instance, because most employees typically spend only part of their work day in a Data Center, the productivity and health benefits are likely to be diminished.

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