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By Paul Schlattman
June 2011 -
Power & Communication Article Use Policy
The opportunities for data center energy efficiency have never been greater. Facility managers can take advantage of new operating techniques as well as the installation of extremely efficient equipment. What's more, energy efficiency is a greater organizational priority than ever before. Campos Research and Analysis recently conducted a survey for Digital Realty Trust. Fifty-five percent of respondents came from companies with revenues of $10 billion or more. When asked the drivers for expansion in 2011 and 2012, their top five answers were:
1. Energy efficiency
4. Power capacity
5. Disaster recovery
Even though most companies are focusing on efficiency within their operating systems, few look at greening from a holistic point of few. Greening the data center really starts as early as the site selection process.
While many factors are accounted for in site selection — including taxes, proximity to corporate headquarters, disaster prevention criteria, available power — green site selection focuses on the amount of annual free cooling, reliable electrical grids, and the availability of existing buildings versus greenfield data centers. Locating a data center within an area that is dry and cool will offer the most opportunity to take advantage of free cooling much of the year. States such as Oregon and Washington offer hydroelectricity, which offers power at $.02 to $.03 per kilowatt-hour, in addition to abundant free cooling thanks to weather conditions.
Other areas of the country that are gaining recognition for hosting data centers because of their cool temperatures are Colorado, Minnesota, Indiana, Illinois, Massachusetts and Vermont.
Another green site selection feature is to locate your data center within a reliable power grid that has sufficient capacity. In 2012, the U.S. Environmental Protection Agency is expected to begin regulating carbon emissions, and if the United States follows the example of the United Kingdom, penalties for carbon emissions may apply. Therefore, the location of a new data center should also consider climates that will help reduce generator runtimes. The three states that have the most data centers also have the most annual power outages. California leads the United States with 508 annual outages, followed by New York with 176 and then Texas with 145.
The second step in site selection is the decision of whether to use an existing building or a new one. If you're planning to try for a LEED certification, the reuse of an existing building is preferable. However, few buildings satisfy data center requirements, which include 150-pounds-per-square-foot minimum floor load, hardened shell, concrete deck roof structures, and 14-foot floor-to-ceiling heights, as well as land to support fuel tanks and thermal storage tanks.
In most cases, enterprise users will prefer to build a new site. Due to the existing conditions and limitations of an existing site, the greenfield site often has the same overall cost (depending on infrastructure design components). Also, there are design features, such as trenching chilled water pipes and pouring depressed slabs, that are difficult to do in existing buildings.
After the site selection process, design and equipment selection is the next step. There has been an array of new technologies that offer excellent efficiencies within support systems.
UPS Technologies: Over the past five years, UPS systems that offer “econo-modes” typically ran off straight utility power, depending on a static bypass switch to transfer load to clean power and batteries. The latest UPS technologies, however, consist of double conversion with three level topologies and are transformerless. These systems offer a 97 percent efficiency rating, while still providing clean power to the server racks.
Chilled Water Systems: While the centrifugal chiller continues to provide efficiencies, especially with waterside economizers, oil-free, magnetic-bearing centrifugal chillers are becoming recognized as an extremely efficient system. While still using chilled water on the data center side, it uses refrigerant on the condenser side thus eliminating one step in the heat transfer and resulting in about 10 percent power reduction. The PUE (power usage effectiveness) typically ranges from 1.06 to 1.2.
Server Technologies: While companies often focus on support system infrastructure efficiencies, migrating to custom servers and DC power is another big step in reducing PUE. Facebook recently announced its strategy within this area. Key components included stripping unnecessary components out of the server box (making it 61 pounds lighter) and using a combination of DC power and AC power servers. This, combined with other green features, has led Facebook to announce a PUE of approximately 1.07 to 1.08.
The third, and final, step in greening the data center is within operations. This would include using hot aisle and cold aisle containment within rack layout, operating chilled water at higher temperatures than normal and capping tile penetrations/air management systems.
The Campos survey also indicated that the average PUE among users was 2.8. Therefore there are several companies nationally and internationally that are focused on upgrading infrastructure to reduce operating cost. However, in many cases the upfront cost to build a new data center is not within the annual budget, and it is always costly to construct a new data center. Many enterprise companies that would historically have built their own facilities are now migrating towards co-location data centers that already offer efficient support systems. For example, a recent 50,000-square-foot Tier III greenfield data center housing 15,000 square feet of raised floor area cost $53 million. The same 15,000-square-foot data center could be moved into a co-located facility at a cost of about $4 to $6 million per year. The upfront capital to build and operate a stand-alone data center is far greater than the initial cost of relocating to a co-location facility.
Taking a holistic approach to greening a data center will create the best PUE and reduce operating costs. The formula is: site selection plus equipment selection plus operating efficiently equals tomorrow's green data center.
Paul Schlattman is the vice president, mission critical facilities group at Environmental Systems Design, Chicago, responsible for business development, project administration and strategic planning of data center, financial, call center and other IT-related projects.