Multi-Building Internet Demand-Response Control System
Researchers at the Lawrence Berkeley National Laboratory (Berkeley Lab) Environmental Energy Technologies Division (EETD) have completed the first successful test of automated demand response in five large buildings (see Figure 1). Demand-response technology manages electricity use in buildings over the internet when high prices, overloaded system conditions, or blackouts threaten the power grid.
"This is the first test of fully automated demand response in multiple large buildings to reduce electricity consumption with two-way internet-based communications," said principal investigator Mary Ann Piette of EETD.
"Demand response" is a catchall term that describes the actions of energy customers who change their electricity demand as a result of changes in electricity prices or emergency requests to curtail energy usage. In this test, "We used a fictitious electricity price to trigger the demand response event over the internet, which is an example of what might be used in the future," Piette explained. "No one touched any control systems during our test. When an XML signal broadcast over the internet indicated that the price of electricity hit 30 cents per hour, the buildings automatically began to lower demand by reducing lights, air conditioning, and other activities. Two-way communications were used to observe that each site was listening to the price signal. When the internet indicated that the price had reached 75 cents an hour, the buildings automatically took additional pre-planned actions to further reduce electrical demand." (XML stands for eXtensible Markup Language, which is used for exchanging structured data over the internet and provides a common language for communicating with internet-based energy information systems (EIS) and different energy-management systems in buildings.)
Commenting on the test, California Energy Commissioner Arthur H. Rosenfeld said "The [Berkeley Lab] study complements current initiatives by the CEC [California Energy Commission] and the CPUC [California Public Utilities Commission] to institute dynamic pricing in California. [Berkeley Lab's] results are encouraging in that they indicate that large commercial buildings using off-the-shelf technology can automatically shed load in response to price signals."
The test, which was funded by the CEC's Public Interest Energy Research Program, was conducted in five buildings: an Albertsons grocery, a Bank of America office building, Roche Palo Alto, a library at the University of California (UC) at Santa Barbara, and the Ronald V. Dellums Federal Building in Oakland. The diversity of buildings tested is an important feature of the project if demand response is to control a large fraction of the state's building stock someday. The test used server technology developed by Infotility to manage the broadcast signal and acknowledge the buildings' responses. Piette and her research team worked with facilities managers at the five locations to integrate the control software in their building control and energy information systems. All five buildings used in the study have state-of-the-art, web-based energy monitoring systems.
"A key feature of this test was gauging the capabilities of today's technology. The test incorporated methods to initiate fully automated demand response control in different building types with different control systems from different vendors. We've demonstrated that many different types of systems can listen to a common XML signal and initiate coordinated load control using the internet," said Piette. The systems tested were: ItronEnterprise Energy Management Suite at UC Santa Barbara, Webgen Intelligent Use of Energy at Bank of America in Concord, Tridium Vykon Energy Systems at Roche Palo Alto, a web service with a custom "BACnet Reader" program and BACnet controller at the General Services Administration (GSA) in Oakland, and Engage Networks/eLutions at Albertsons in Oakland. The manufacturers of these systems received funding from the CEC's California State Assembly Bill 970 and Senate Bill 5X Demand-Response programs to enhance control and internet connectivity features.
The test unfolded during a two-week period as Berkeley Lab, working with Infotility, sent a continuous XML signal to the five buildings' demand-response systems, which were programmed to accept XML signals. On two occasions, the signal indicated increased electricity prices, which initiated automated load reduction. Facility managers at each site decided ahead of time which loads would be reduced by the automated response system. Berkeley Lab collected data on how the systems responded to the price-increase signal and evaluated the response performance.
"Albertsons was interested in learning more about what our ability would be to curtail load based on pricing signals. We also wanted some insight into how those pricing signals would be sent and interact with our controls, preferably without human intervention," said Glenn Barrett, a spokesman for the grocery chain. "We learned we do have the ability to react to changes in commodity pricing and make changes in our stores that will allow us to curtail load. It also lays the foundation for a web-enabled solution that could be applied to any store across the state of California."
Automated demand response would be a great advantage for consumers as "California is investigating 'dynamic pricing' tariffs as a long-term, sustainable strategy for mitigating electricity supply-demand imbalances that can result in high prices and forced outages," says Piette. "One form of these tariffs would offer rate discounts when system conditions are normal-most of the time-and charge higher rates, called critical peak prices, when the grid is approaching an overloaded state or during wholesale price spikes."
Automated demand response to a dynamic pricing strategy is advantageous for the electricity system as well. If a power plant or transmission line goes down, dynamic rates (or signals) can quickly reduce power demand and thus the likelihood of a full-scale outage. Some electricity grid experts believe that a system with automatic demand response could have avoided the August 14, 2003 blackout in the eastern U.S. and Canada.
Dynamic rates can also signal wholesale electricity costs to the energy market; these costs tend to be highest when electricity demand is unusually high or when supply is unusually low. During a few critical days per year in California, (usually the hottest days), wholesale prices can spike to 10 times the normal price or even higher. Current retail electricity rates don't reflect these unexpected changes in wholesale prices, so customers have no motivation or incentive to reduce demand when a reduction could help the system continue to function reliably. A dynamic rate structure benefits customers, allowing them to reduce monthly bills by reducing usage during periods of high prices or by shifting usage to periods of low prices.
Future research will include additional testing and analysis at the five sites used for this demonstration project as well as at other sites. Eventually the majority of commercial buildings could be managed dynamically using demand-response systems, reducing the likelihood of blackouts.
Others who participated in the test include Osman Sezgen, David Watson, and Naoya Motegi of Berkeley Lab; Joseph Desmond and Nicholas Kardas of Infotility; Gaymond Yee of the California Institute for Energy Efficiency; and consultant Christine Shockman.
For more information, contact:
- Mary Ann Piette
- (510) 486-6286; fax (510) 486-4089
This research is funded by the California Energy Commission's Public Interest Energy Research program.