Taming the Beast: Making Data Centers More Energy Efficient
- By Matthe Parker
- April 1st, 2009
Without question, sustainable building design has emerged as more than just a good idea. With increasing energy costs and public awareness, plus a growing list of certified “green” buildings, measurable data from completed buildings demonstrates that sustainable design works and can easily be cost competitive with conventional design and construction.
Of all the building types now undergoing these changes, the modern data center is the most elusive. The exponential growth of computing technology shows no signs of letting up, and data centers are now considered the largest consumers of commercial energy, both in existing demand and projected growth. In many cases, a data center occupies only a portion of a much larger building, but its energy consumption alone drives many of the building’s sustainable design decisions.
Because data centers are such energy hogs, many building owners assume they can’t pursue a LEED-certified green building because their center cancels out the sustainable effects of the rest of the building. But by applying some of the fundamental tenets of sustainable design to data centers, building operators may be able to reduce their energy usage and tame the energy “beast.”
Reduce, Reuse, Recycle
While this mantra is basically the core of sustainable design, it’s often foreign to the data center environment. However, there are ways to apply all three ideas to a data center during different phases of its life cycle, moving its design and operation into the sustainable world.
Simply put, do more with less. The most effective way to reduce in the data center environment is to increase its efficiency. A typical data center groups computing equipment in floor-mounted racks. How these racks and the equipment they contain are arranged greatly impacts the efficiency of the room. A typical rack is about 50 percent full to assure there is plenty of room for waste heat to escape. In many cases, however, the waste heat is poorly managed, and mixes into the conditioned cool air. By extension, data center floor space and support equipment are often purposely oversized to accommodate this inherent inefficiency.
Two ideas — while not new or even original — can significantly increase the efficiency of this organization. First, simply rearrange equipment to take full advantage of rack space. Instead of housing 50 racks that are 50 percent full, operate 25 racks at 100 percent each. While the net power consumption is roughly the same and the power density in each rack is actually increased, the need for more cooling and floor space is significantly reduced.
Second, new design concepts for data center planning provide guidance for “right-sizing” a facility to eliminate traditional inefficiencies and focus on improved layout and operation. The “footprint energy arrangement redundancy,” or FEAR, model, for example, optimizes the arrangement within the data center, significantly reducing the typical amount of energy used by a data center. By combining these kinds of best practices for both process and support equipment, the data center’s energy consumption could be reduced as much as 75 percent. And, it only takes a 38 percent reduction in data center energy to generate a 100 percent return on investment in fewer than five years, adding a convincing business case to the already compelling environmental argument for greener facilities.
This concept is a difficult one to implement in data centers. Historically, technology equipment becomes outdated in as little as 18 months as manufacturers continue to improve their power and efficiency. But in the larger building context, simply reusing interior spaces for data center support can help.
Most facilities locate employee workspaces around the perimeter of a building to give people more exposure to natural light, leaving interior spaces for equipment storage and other uses. Data centers can be incorporated into these interior areas, placing them closer to the mechanical and electrical spaces that often serve them.
Virtualization, or pooling, of information technology equipment also espouses the reuse philosophy. On a basic level, current computing equipment uses dual or quad core processors within one server or process box. If you combine that processing within a single box — in other words, allow one piece of equipment to function as two or more servers— the processors will be using up to 100 percent of their power for actual processing, versus the 30 to 50 percent used when each server is housed in a separate box.
Energy recovery can also help a data center reuse its resources. While this can take many forms, two of the most common means are to pass heated air, water, or other media through a heat exchanger to redirect waste heat for another building function, such as heating the water. That means rethinking the data center as a source of heat rather than a source of heat waste. Many newer building systems have done just that, making capturing waste heat more economically viable. The challenge now is to design systems that can be used across diverse geographic regions with differing climate considerations.
A movement is underway in the U.S. to adopt the Restriction of Hazardous Substances (RoHS) Directive, a European idea adopted there in 2006. Essentially, the directive requires equipment manufacturers to modify their manufacturing techniques to reduce hazardous materials contained in electronic products and to find ways of recovering hazardous materials for newly manufactured and end-of-life equipment.
By modifying specifications for new equipment and implementing decommissioning procedures, data centers can comply with these requirements and begin recycling with very little effort. To comply with RoHS, manufacturers must document their efforts, which translate to the LEED certification process. Additionally, recent changes to the National Electrical Code require old cables and conductors to be removed from a renovated facility, and data center owners, contractors, or consultants can specify that those removed cables are recycled.
LEED and Data Centers
With few exceptions, a data center can and should be considered no differently than a commercial office building when it comes to LEED certification. As such, most of the LEED credit categories can be applied to data centers without special consideration. The prevailing mindset in data center design focuses on the fact that LEED credits in the energy and atmosphere categories are difficult to obtain because of the intense energy requirements of data centers. In fact, the details of the LEED rating system allow for 25 percent of a building’s energy profile to be designated as process loads, which specifically include office equipment and computers. So, in many cases, a small to medium-sized data center within a much larger building may fit within the “normal” building profile and have no effect on the building’s overall energy efficiency.
With a proper mix of new technology and modified thinking, implementing some relatively simple design concepts opens the door for LEED certification in data centers, or, at the very least, a more concerted effort toward being environmentally responsible within them. All it takes is a little creativity and willingness to try.
Matthew Parker, PE, RCDD, is an electrical engineer and project manager with consulting firm Stantec. For more information on data centers, contact Matt at 919/865-7524 or firstname.lastname@example.org.