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UC San Diego Cuts Electricity
Purchases 80 Percent During State
Heat Wave ‘Demand-Response’ Program

Aug 30, 2010

By Rex Graham

Photo of Dilliot
John Dilliott, director of energy and utilities for UC San Diego, watches electricity imports from San Diego Gas & Electric plunge in the wake of aggressive campus-wide energy-management steps were taken this week.

During Aug. 23-25 when California’s afternoon temperatures rose above 100 degrees, UC San Diego took a variety of energy-conservation steps, including simultaneously adjusting thousands of thermostats a few degrees warmer than normal to help cut electricity purchases up to 80 percent during three state-wide “demand response” events.

UC San Diego faculty and staff switched from desktop computers to more energy-efficient laptops and turned off printers and other office equipment not in use and took many other measures as part of an effort to restrain electricity consumption. As a result, UC San Diego reduced its purchase of electricity from 10.5 megawatts to only 2 megawatts during a critical two-hour period on Aug. 25 and reduced electricity purchases by similar amounts during the two previous afternoons.

“The campus already produces 82 percent of its own power with solar panels and a highly efficient, low-emission gas-fired power plant,” said Gary Matthews, vice chancellor of Resource Management and Planning. “Our energy-management system, which is part of our increasingly sophisticated energy grid, also enables us to very effectively reduce our imports of electricity when the state energy system is taxed.”

Sola Tube
Pre-school students at UC San Diego’s Mesa Child Development Center helped turn off all electric lights at their center to conserve energy this week. Windows and ceiling “Solatubes” provided ample light.

Even 24 pre-schoolers and their teachers at UC San Diego’s Mesa Child Development Center reacted to a central campus email on Aug. 25 that asked for voluntary conservation. The children and their teachers turned off all the center’s electric lights and read books, colored and completed projects with light delivered by overhead Solatubes. The advanced optics devices made by Vista, Calif.-based Solatubes International deliver sunlight to dimmable ceiling fixtures.

The recent heat wave was not accompanied with brown-out warnings to the public. The state's electric power suppliers were able to add additional capacity to supply the electricity demand even as temperatures in many parts of the state passed the 100-degree mark. However, the California Independent Service Operator (Cal ISO) this week asked major power users to take pro-active “demand-response” measures to curtail their electricity use during high-demand times in the afternoon.

Central Utilities Plant
UC San Diego’s highly efficient natural-gas-fired cogeneration power plant saves the university $670,000 per month in energy costs.

In collaboration with Cal ISO, San Diego Gas & Electric manages demand-response programs that offer a financial incentive to customers who voluntarily reduce their energy use during times of peak energy demand. The program helps to maintain a real-time balance between electricity supply and demand. UC San Diego participated indirectly in three SDG&E demand-response events the week of Aug. 23 as well as four the previous week through EnterNOC, a Boston, Mass.-based 3rd party provider. EnterNOC acts as a 3rd party demand-response resource for three investor-owned utilities in California, including San Diego Gas & Electric.

"As our region’s population continues to grow and we fill our homes with new technologies and air conditioner units, we need to look for ways to reduce the peak demand on the grid," said Mark Gaines, director of customer programs for SDG&E. "By reducing their peak demand, demand-response program participants like UC San Diego help the environment by reducing the use of the oldest, least efficient power plants today and reducing the need for more power plants to be built in the future."

UC San Diego responded in a highly coordinated way to reduce electricity purchases during the demand-response events the week of Aug. 23:


  • The morning of Aug. 25, an email to all faculty and staff noted the high-temperature forecast and offered 10 voluntary recommendations to lower energy usage, such as turning off unnecessary lighting, setting air conditioning thermostats no lower than 78 degrees, and turning off office equipment not in use. (Many campus machines are “Energy Star” certified and already reduce energy consumption to a trickle during periods of inactivity.)
  • About 75 minutes before the start of the 2 p.m., Aug. 25 demand-response event, microgrid operators switched thousands of thermostats to an energy-saving "unoccupied" status. The operators control 4,500 thermostats on the campus and the controls in non-critical areas were adjusted.


  • About 30 minutes before the 2 p.m., Aug. 25 start time, the university shut down 3 megawatts of electric water chillers. Cold water from the chillers cools most campus buildings. When the chillers go off-line, cold water produced overnight as a back-up and stored in a 3.8-million-gallon tank is sent via underground pipes to campus buildings to cool them, significantly reducing their afternoon electricity demands.
  • The campus operates a 27-megawatt gas-fired cogeneration power plant. In addition to that electricity production this week, its waste heat and steam were tapped during the demand-response times to power an additional 3 megawatts of electricity and steam for building-heat situations and laboratory equipment.


  • The campus produced 4.7 megawatt-hours of solar electricity during last week’s three demand-response events from photovoltaic panels on campus rooftops and parking garages.


Photo of UCSD Demand
The bottom line on this graph of UC San Diego’s energy production and usage on Aug. 25 shows that the university’s imports of electricity from San Diego Gas & Electric fell from 10.5 to 2 megawatts during a state-wide demand-response exercise 2-4 p.m. that was designed to lower electricity demand on California’s energy grid.

The net result of all the measures accumulated on Aug. 25 to an 8.5-megawatt reduction in electricity purchases from the energy grid. Campus energy managers and grid researchers intentionally staggered each energy-saving action the afternoon of Aug. 25 in order to quantify and evaluate the impacts of each move.

“We’ve participated in the demand-response program since 2001 and the financial incentives of the program save the university up to $50,000 a year,” said John Dilliott, manager of energy and utilities for UC San Diego. “We use that money to plow into additional energy-saving technologies such as centrally programmed thermostats, which in turn save the campus even more money.”

“Much analysis will be needed to quantify the impacts of all the steps we took, but what we know already is that our microgrid is extremely agile, integrated and capable of rescheduling key energy-saving actions as the situation dictates,” said Byron Washom, UC San Diego’s director of strategic energy initiatives. “By the end of the year, our microgrid optimization and will increase significantly with the installation of a suite of advanced smart-grid software.”


Media Contact: Rex Graham, 858-534-5952, ragraham@ucsd.edu

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