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The “Demand” Response—Training Wheels to Energy Efficiency
American universities and colleges, much like commercial and industrial facilities, are often poorly equipped to assess their own energy use. Less than one percent has any sort of real-time monitoring system.
“It’s like getting your phone bill and not being able to see who you called and how long you talked in order to make adjustments,” says Greg Dixon, senior vice president of sales for EnerNOC, Inc. The Boston firm provides “demand response” expertise and technology, enabling customers to monitor their own energy use and cut back.
Demand response represents a multi-faceted movement, young but deeply rooted in government, industry, and education. The concept has launched billion-dollar companies and new courses of academic study. Through utility-sponsored programs, it provides new avenues for large-scale energy users to cut energy use, reduce their environmental impact, and often bring in substantial new cash in the process. And the design and operation of university-based demand-response systems employs not only faculty and staff, but often students preparing for life in a lower-consumption world.
In central California, the College of the Sequoias signed up in 2006 for Clean Green California in mid-2006. The utility-backed program was born after blackouts rolled through the Golden State in 2000 and 2001.
Grid-emergency “events” happen five to 10 times per year, usually on hot summer days between 2 and 6 p.m. according to Eric Middlestead, Dean of Facilities and Facilities Planning at the college. “Our demand response is primarily to reduce air conditioning,” he said.
With a few computer keystrokes, he or a staff member responds by upping the temperature by four degrees in air-conditioned areas in approximately 40 buildings rooms. Most are set around 74 degrees Fahrenheit normally and 78 during the event. The A/C is switched off entirely in hallways and bathrooms. Energy use typically drops by about 250 kilowatts during an event.
“The first time we did it, about a dozen people called to complain. When we explained what we were doing, they were all very supportive,” said Middlestead. The next couple of times, the school was warned a day in advance by the local utility. Students and faculty were warned as well, and again the response was overwhelmingly supportive.
For its trouble, he estimates, the college will have received between $10,000 and $12,000 during its first year of participation, which is now drawing to a close.
Working and studying at the University of Maryland are nearly 50,000 students, faculty, and staff. Its College Park campus consumes 205 megawatt hours of juice per year. Two years ago, it was eight percent higher, says Mike Krone, manager of utilities operations. Then it enrolled in a demand-response program sponsored by PJM, the Regional Transmission Organization serving the Mid-Atlantic States.
Like his counterpart in California, Krone responds to grid emergencies mainly with the thermostat. “We coast our air supply system during the day, which normally runs 24-7, and shift some of the load to nighttime,” he said.
On a single hot August day in 2007, PJM says voluntary demand reductions in its three-state region saved 1,945 megawatts of electricity. That’s the amount of energy used by a mid-sized city. A 2007 report by the Federal Energy Regulatory Commission estimated that demand systems nationwide lowered electricity consumption by 1.4 to 4.1 percent in overstressed systems during peak periods in 2006.
More evidence of demand-response effectiveness is in the energy-trading markets, according to Krone. Megawatt-hours are traded on an exchange much like stocks or commodity futures. Today’s prices exhibit nearly no volatility, in contrast with wild swings as recently as 2003, when a major blackout hit the Northeast.
“The grid has been really quiet,” he said. Krone credits demand-response systems directly for encouraging conservation.
Preparing for Renewable Energy
At the University of New Mexico, a $500,000 grant from the U.S. Department of Energy is paying for two separate demand-response systems. One monitors a temperature-control system that will use chilled water to cool a single building. The other involves retrofitting several buildings with sensors and instruments to control various conventional heat and ventilation systems.
Particularly challenging is the development of related software, says Andrea Mammoli, associate professor of mechanical engineering at UNM. “The expense is not trivial,” he said. New hardware will include digital controllers and variable-frequency drives for fans. With the resulting changes in airflow will come the need for improved zone control. HVAC vents must open and close in close coordination with changes in fan speed so that the building’s farthest reaches are well served. Most universities have an electronic EMS or emergency management system, said Mammoli. Installing demand-response technology is a matter of integrating it well with the existing system.
The big benefit of demand response, Mammoli expects, will relate to energy production, not consumption. More renewable energy sources are coming online, but because of their intermittent nature, there’s a need to sense their availability and tap them instantaneously. The process will rely on the same sort of sensors and controls now used in demand systems.
Many demand-response systems already gauge inputs as well as outputs. An example is the Leslie Shao-ming Sun Field Station, built on a biological preserve at Stanford University. The building was designed for net zero carbon emissions and a minimal environmental footprint. Reported in real-time are energy data including wattage arriving from the grid or being pumped back into it, propane consumption, solar panel voltage, and temperatures of individual solar arrays.
Typically, the data is viewable in an online “dashboard,” shown in technical bar graphs and histograms. Often it is also displayed in a public place such as the common area of a dorm. The flat panel screen may double as a kiosk for announcements and perhaps a plug-and-play outlet for video games.
Student-designers at Dartmouth College leveraged the high-profile placement of their dashboard with an appeal to the heart as well as the head. A monitor displays a cartoon-like meter moving up and down with actual energy use. Beside it, an animated polar bear is sleeping happily on an ice floe. But when energy use rises, incrementally, the bear’s plight worsens. Eventually he plunges through the ice and appears to be drowning. Students have reacted with panic, dashing through the dorm to switch off lights and save the bear.
“Charts appeal to the technical side. This gets people emotionally involved,” said Lori Loeb, a Dartmouth professor of computer science. Loeb directs a minor program in digital arts, and conceived of the polar bear idea.
“I haven’t proved this, but my hypothesis is that when you warm the data emotionally, people pay more attention to it,” she said. She and some students are building a business to distribute the concept to institutions and eventually perhaps homeowners.
In Minneapolis, architecture firm LHB is designing a system for Carlton College, located 45 miles to the south. Under construction are two new residence halls that will house 230 students. In one, energy use will be monitored “per floor.” The other will monitor consumption for every suite, says LHB architect Maureen Ness.
“Monitoring individual suites creates an incentive for students to use energy wisely,” she said. “When they see they’re using a lot more energy than their neighbor, maybe they shut off something they don’t need—such as a coffee maker.” Students sometimes set up energy-cutting competitions.
Voluntary responses to demand, as opposed to the automatic kind, are great but not always practical, Ness notes. Systems vary widely, and many rely on a mix of individual responses and system-wide actions by a single administrator. Pre-programmed shutdowns, often sequential and nuanced according to many conditions, may be effective in manufacturing. But university-scale systems are smaller in scope. “They’re talking megawatts. We’re talking kilowatts,” said Ness.
Best practices in demand response necessitate enlisting certain key personnel. Particularly important, said Ness, are the technical people who manage the physical plant. Sequoias administrator Middestead agrees. But the resources are spread thin, he warned. “The facilities department is key, but I have yet to see one that’s overstaffed.”
Any demand-response installation is a positive step, says Greg Dixon of EnerNOC. “It’s like training wheels on your way to true demand-side management. You get the foundational technology to see how you’re doing in terms of energy management. You can’t manage what you don’t measure.”
Sub-metering Campus Buildings: EPA (PDF)