Sustainable By Design: Does It Pay To Pursue Plug Load Reductions?
By Anne Cosgrove
Published in the January 2009 issue of Today's Facility Manager
Amidst the uncertainty of the future of this country’s energy infrastructure, facility managers (fms) can take matters into their own hands by focusing on reducing consumption and costs with the systems and equipment already in place in their buildings. Increased energy efficiency is one form that this strategy can take. Many experts in the field are pointing to this approach as a way to stem the tide of expected exponential demand over the next two decades
Plug loads are an area for fms to consider. These loads are represented by devices that plug into a facility’s electrical system; this includes office equipment (e.g., computers, monitors, speakers, fax machines, printers, copiers, and task lighting) as well as appliances and other items commonly found in the workplace (e.g., refrigerators, vending machines, audiovisual equipment, space heaters, coffee machines, and water coolers). Additional devices can add to the plug load (e.g., in a hospital, MRI and X-ray machines). In short, plug loads consist of any electrical equipment that is plugged into a wall outlet.
So how large of a part do plug loads play in a building’s energy consumption? Consumption, of course, varies by building and industry sector; however, the U.S. Energy Information Administration (EIA) estimated that, in 2006, office equipment and miscellaneous items together would consume 2.18 quads (close to 640 billion kilowatt hours) of energy.
As part of its work helping clients reduce energy use and manage carbon emissions, ECOS Consulting in Portland, OR assists organizations in identifying the impact of plug loads. Greta Melvin, plug load specialist; Gregg Hardy, consumer electronics market development; and Geoff Wickes, director commercial & industrial solutions have experience working in this aspect. They point out that since the 1980s there has been continual growth in the use of electronic office equipment, “particularly personal computers and monitors, but also printers and multi-function devices, which are replacing discrete copiers, fax machines, and scanners in some office environments. Plug load has grown from 2% to 3% in the early 1990s to well over 12% to 14% in 2007.”
This growth is in spite of improvements in energy efficiency, which are expected to be offset by continuing penetration of new technologies and use of office equipment, notes the ECOS team.
So what can fms do to identify plug load items and measure their impact on overall consumption?
The ECOS team advises: “One way to determine plug load is to look at a ‘value stream’ map for energy coming and out of a building. Identify what percentage of the load is heating and air conditioning, lighting, controls, other mechanical load (e.g., pumps, elevators), and finally plug load. Once percentages are determined, review the building to benchmark standards for similar buildings. If plug load is significantly higher than 12%, [fms] should investigate. Take an inventory of the load and break it down into major categories; then begin some data collection. Install plug load meters on common devices to record average energy usage. Extrapolate.”
Another approach is to conduct a physical audit of the facility in order to inventory items that contribute to plug load by calculating hours of operation and average wattage. Fms can have staff members (or an outside firm, if budget allows) catalog each piece of equipment deemed to be a plug load contributor.
In a 2006 study by the Lawrence Berkeley National Laboratory (LBNL), six researchers audited 16 facilities in three cities (Atlanta, Pittsburgh, and San Francisco). The team conducted a series of after hours surveys, recording the number and types of office equipment (OE) and miscellaneous equipment (ME). In all, the team audited approximately 4,000 units of OE and 6,000 units of ME, noting items “ranging from electric pencil sharpeners with a unit energy consumption (UEC) of 1 kWh/yr to a kiln with a UEC of 7,000 kWh/yr.”
Among its findings, the LBNL team identified several types of equipment as notably large energy consumers. The top five were cold beverage vending machines, commercial refrigerators, computer speakers, Ethernet switches, and commercial freezers. (Fms should check condenser coils on vending machines and refrigerators, since dust and other debris on those coils can prevent efficient heat transfer—and increase electrical load.)
After plug load data has been calculated, what can an fm do to tackle the task of reducing energy consumption?
An effective strategy might comprise purchasing energy efficient equipment (those with the EnergyStar label are a good start) and installing auxiliary tools such as power strips programmed to minimize or shut down power. Fms can also implement policies and educate occupants on how to reduce unnecessary energy use; internal memos and posted notices can remind occupants to shut down task lighting, computer monitors, coffee makers, and televisions.
Other suggestions, from the ECOS team, include: upgrading to newer equipment (older items, such as CRT monitors, can use significantly more energy than newer LCD monitors) and recognizing that as plug loads increase, fms will need to pull more circuits onto the floor, and the infrastructure cost can be prohibitive. “It’s better to work on reducing the load,” advises the team, “rather than masking the problem with more power applied to the floor. Many new efficient products also improve Power Factor Correction (PFC). Improved PFC reduces wire size, improves system reliability, and reduces the need for additional equipment.”
Until recently, plug loads have been largely overlooked as an energy efficiency strategy for facilities. But with this type of consumption expected to continue rising, fms may want to look at how much energy and money is being spent on unnecessary demand.
Research for this article included information from ECOS Consulting, LBNL, and EnergyStar.
Have you tackled plug loads? Send an e-mail to email@example.com. This article is the last in the Sustainable By Design series from Vazquez.
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