Chapter 1: Going Green in the Data Center

Cisco Press

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Alternately, because Data Centers involve drawing much more power than other building spaces, green improvements can easily achieve much more than $5.79 per square foot ($62.32 per square meter) in energy savings over 20 years.

A study conducted by Lawrence Berkeley National Laboratories for the American Council for an Energy-Efficient Economy determined that Data Center energy costs are typically 15 times those of typical office buildings. The 2006 study, Best Practices for Data Centers: Lessons Learned from Benchmarking 22 Data Centers, reviewed 22 Data Center buildings and found some server environments were as much as 40 times as energy-intensive. Apply those multiples to the energy-savings figures in Table 1.1, and you have potential savings of $86.85 per square foot ($934.85 per square meter) in an average Data Center and of $231.60 per square foot ($2492.94 per square meter) in the most power-hungry rooms.

Table 1.1 Financial Benefits of Green Buildings


20-Year Net Present Value (per Square Foot)

20-Year Net Present Value (per Square Meter)

Energy Savings



Emissions Savings



Water Savings



Water Savings (construction only)—1 year



Operations and Maintenance Savings



Productivity and Health Benefits

$36.89 to $55.33

$397.08 to $595.57


$52.87 to $71.31

$569.09 to $767.58

Average Extra Cost of Green Building



Total 20-Year Net Benefit

$48.87 to $67.31

$526.04 to $724.52

If you develop a business justification about why to pursue green initiatives at your company, you undoubtedly need to quantify your return on investment. In simple terms, if the business expends resources on an initiative, typically in the form of money or staff time, how long will it take for that expenditure to be repaid as a result of the changes?

Even if you never performed a formal ROI analysis in your job role, you have probably done the mental exercise instinctively as a private consumer. For instance, if you consider buying a compact florescent light bulb for your home, you likely thought, “If I have to pay x more for a fluorescent light bulb than I do for a standard one, but the fluorescent bulb saves me y on my electric bill every month, that’ll pay for itself in z months.”

There are more variables when considering green improvements for a server environment, but the basic approach is the same: What’s the upfront cost and how quickly can you recoup it?

Say, for example, you decide to cover the notched openings in the floor tiles of your Data Center’s raised floor, to improve the static pressure in the room and thereby increase the efficiency of the air conditioning system. (Sealing unwanted openings across the Data Center prevents chilled air from leaking out and not fully reaching the equipment it is supposed to cool.)

If the Data Center has 100 cabinet locations with tile openings and you spend $50 per cover (there are many cover types on the market, from foam rubber to bristle brushes), that’s $5000 in upfront costs. Assuming the subsequent improvement to the Data Center’s air flow reduces the power draw of the cooling system enough to save $200 worth of energy each month, you earn back the price of the caps in approximately 2 years ($200 × 25 months = $5000).

Changing any of the variables alters how long it takes for the improvement to pay for itself. The data points to consider in this case include the following:

  • The cost of the improvement: In this example, the $50 price tag for the tile covers. More expensive covers obviously take more time to pay for; less expensive covers less time. Because your support staff will spend time installing the covers, you could conceivably factor in a labor cost as well. (I wouldn’t in this particular case, because the work is negligible enough to be absorbed into the staff’s regular workload.)

  • The baseline operational costs: In this instance, the monthly electrical bill for the Data Center, which includes the cost of powering the cooling system before the tile covers are installed. Note that this actually includes two elements—how much energy is consumed and the local cost of electricity. This becomes relevant if you consider making an improvement in multiple Data Centers located in different cities that are, therefore, subject to different electric utility rates.

  • The projected impact of the operational improvement: How much energy do you save by improving static pressure in the Data Center, and therefore how much lower will the electric bill be? The more dramatic the improvement, obviously the faster you recoup your initial expense. Accurately gauging the savings provided by some green improvements can be challenging. Installing a more efficient PDU can be relatively straightforward to measure, for instance, whereas other improvements such as floor tile covers can be less exact. Be prepared to estimate savings and take measurements after they are installed.

A more comprehensive analysis can also cover other impacts of making the improvement. For instance, the improved airflow might lower the overall temperature of the Data Center, which is generally better for servers and provides a greater safety margin if an air handler malfunctions.

A NetApp Data Center in Sunnyvale, California, illustrates the financial benefits that come with a green Data Center. The facility, opened at NetApp headquarters in 2008, in building space previously used for manufacturing, includes a variety of energy-efficient design elements that save the company more than $1 million per year compared to the operational costs of a conventional server environment.

The Data Center is 14,500 square feet (1347 square meters) in size and involves an additional 5500 square feet (511 square meters) of surrounding building space for air handlers that cool the hosting area. The 720-rack Data Center has 5.76 MW of electrical capacity for IT hardware and 7 MW overall. About 20 percent of the Data Center floor space is supported by standby electrical infrastructure; the remainder is not.

Energy-efficient measures including air economizers, a variable chiller plant, energy-efficient transformers, and rotary uninterruptible power supply (UPS) systems save more than 11.1 million kWh in annual energy usage, thereby conserving more than 6.7 million pounds (3039 metric tons) in carbon dioxide emissions and saving more than $1 million in operational costs per year, according to Ralph Renne, NetApp director of site operations.

Table 1.2 shows the annual energy, carbon, and costs savings of the facility over a conventional Data Center, broken out among three main categories of green improvements.

Each of the energy-efficient measures implemented by NetApp are explained in detail in Chapter 4, “Powering Your Way to a Greener Data Center,” and Chapter 5, “Cooling Your Way to a Greener Data Center.”

Capacity Gains

Because the essence of a green Data Center is to use resources more efficiently, it follows that a green facility gets more out of those resources than a room that hasn’t been designed in that manner. To put it another way, if one car is more fuel-efficient than another, it can go farther on the same amount of gas.

Many Data Centers, especially those built more than a few years ago, have power and cooling constraints that significantly limit to what extent a company can fill its server cabinets with gear. Making those server environments greener can stretch its power and cooling resources farther, opening up valuable hosting capacity that was previously unusable.

Achieving such capacity gains could conceivably allow your company to defer construction of a Data Center—along with the capital and operational expenses that come with it.

Note - Imagine if you can make enough efficiency improvements to your existing Data Centers to actually take some of your server environments offline altogether. I can’t think of a more dramatic example of a company making its Data Center portfolio greener.

Table 1.2 Annual Savings from a NetApp Green Data Center

Green Element

Energy Savings (kWh)

Carbon Savings (lbs./Mtons)

Cost Savings

Mechanical systems


5,468,636 (2481)


Rotary UPS systems


882,569 (400)


High-efficiency transformers


431,834 (196)




6,783,039 (3,077)


Increasing Regulation

Even if your company doesn’t see a driving need to make your server environments greener, it’s likely that your government does—or soon will. Government officials worldwide are paying increasing attention to environmental concerns, from energy consumption rates to dependency upon oil to global warming.

Although no mandates specifically call out Data Center restrictions, the tremendous environmental impact of these rooms make them a prime target to place limits on to meet various environmental pledges. A green Data Center is much more likely to be compliant with current and future environmental regulations than a conventional Data Center.

Recent Government Green Commitments

China published a National Climate Change Program in 2007 that set goals to improve its energy efficiency by 20 percent in 2010 (compared to 2005 levels) and to raise the proportion of renewable energy to 10 percent of its primary energy supply by 2010. The country previously passed the Renewable Energy Law that targeted increases in the use of various renewable energies by 2010 and 2020 and committed to investing $180 billion in renewable energy during that time. If the targets are met, renewable energy will account for approximately 16 percent of the country’s energy consumption in 2020.

India introduced the Energy Conservation Building Code in 2007 that is expected to reduce power consumption in commercial buildings 25 percent to 40 percent by way of minimum efficiency standards for external walls, roofs, glass structures, lighting, heating, ventilation, and air-conditioning systems. The codes are to be mandatory for commercial structures with an electrical load of at least 500 kW—a power budget easily exceeded by even medium-sized Data Centers.

Japan’s Ministry of Economy, Trade, and Industry announced a New National Energy Strategy in 2006 that includes the goal to improve energy consumption efficiency at least 30 percent by 2030.

Sweden’s Minister for Sustainable Development made headlines in 2005 by announcing a goal to eliminate the country’s dependence upon fossil fuels by 2020. To achieve the goal, the government is increasing research on alternative fuels, expanding a quota system introduced in 2003 requiring all electricity customers to buy an increasing percentage of renewable energy, and offering tax breaks for homes and vehicles that use renewable fuels.

The United Kingdom has announced goals to reduce greenhouse gas emissions by at least 80 percent by 2050 (compared to 1990 levels) and is driving to that goal in part through its Carbon Reduction Commitment (CRC). The CRC is a mandatory carbon emissions trading scheme that, effective 2010, requires organizations that consume at least 6000 MWh per year in electricity to buy carbon credits. For the first 3 years of the program, costs are £12—about $18—for each metric ton of CO2. By 2013, carbon allowances will instead be auctioned, and the total number of them will be capped, ultimately forcing reductions in carbon emissions.

In the United States, a growing number of state governments have adopted renewable portfolio standards, which call for a certain portion of utility power to come from renewable sources. Twenty-four states and the District of Columbia have mandatory requirements, and four others have declared nonbinding goals. Their popularity appears to be growing, as half of the standards have been developed since 2004.

The portfolio standard programs vary widely, differing over details such as minimum thresholds of renewable energy, whether energy efficiency should figure into usage calculations, and deadlines to meet the standards. The inability to agree upon one common approach is why no federal renewable portfolio standards exist.

Note - When considering, from a green perspective, where to build a Data Center, it is useful to know what regional standards are in place for power content and emissions. The higher percentage of energy powering your facility that is renewable, obviously the greener the Data Center is to begin with. Chapter 4 discusses electrical mixes in greater detail.

The EPA report on U.S. Data Center power consumption, mentioned previously, was actually initiated by 2006 federal law (Public Law 109-431) “to study and promote the use of energy-efficient computer servers in the United States.” When formally presented to Congress in 2007, there was some anticipation within the Data Center industry that U.S. legislators would respond by setting restrictions on Data Center energy usage. Although none have been introduced as of this writing, the EPA is continuing its focus on Data Centers by developing energy rating standards for servers and Data Centers, similar to the one it uses to rate appliances for their consumption. Chapter 4 and Chapter 8, “Choosing Greener Gear,” provide additional details on those efforts.

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