results have been remarkable. In the first four work weeks of July last year, Opto 22 consumed between 575 and 650 kW-hof power. This figure is down considerably from the 660-to-871 kW-h of the previous year. August saw even greater reductions. “In spite of almost monthly double-digit price increases last year, we’ve been able to keep our overall bill at approximately the same level,” says Engman.

Ethernet for utilities

Rising energy costs are not the only force changing the economics of automating building services. The migration of Ethernet from offices onto the factory floor has had a big impact over the last decade. “We can make use of the existing Ethernet network,” says James Davis, senior applications engineer at Opto 22. “And if one’s not in place, there are many wireless solutions.” The ability either to plug into a standard network or to broadcast to a receiver can eliminate the

Davis also points out that open systems make the spectrum of robust tools already in place for controlling and monitoring process equipment available for automating buildings. Open systems played a role in the University of Cincinnati’s decision to replace the distributed controls system that it had been using in its utility plants. Besides providing the steam, chilled water and electricity for a 420-acre university with 34,000 students, the plants also supply the same services to

“When you’re serving universities and hospitals, reliability is critical,” says Joe Harrell, director of the university’s utilities. But his concerns don’t end there. “We are a miniutility company. So in addition to being reliable, we also want to keep our costs low, as well as remain environmentally friendly.” Not only were theagingcontrolscausingsomereliability problems, but they also bound the university to the supplier for service and equipment.

For these reasons, the facilities management department decided to install an open controls system capable of being maintained by the university and of exploiting more robust, industrial-grade technology. Fosdick and Hilmer, a Cincinnati-based engineering and systems integration firm, built the control system around FactorySuite automation software from Wonderware, a Lake Forest, Calif. based unit of Invensys Systems Inc.

By means of fiber-optic cable, a high-speed Ethernet network now links the 11 programmable logic controllers (PLCs), nine process automation controllers and other instrumentation that oversee the equipment and storage tanks. Also on the network are nine workstations running Wonderware’s InTouch human-machine interface (HMI) software. Wonderware’s IndustrialSQL Server historian collects demand and process data in real time and stores them in archives for trend analyses and optimization.

Energy optimization software tracks the demand across 60 buildings and directs the delivery of services based on equipment availability and current fuel prices. “The dynamics vary almost every day,” explains Harrell. “We can buy electricity from the [public] utility, or we can produce it ourselves with natural gas or fuel oil.”

Not only does the software tell the operators what is happening in the processes, which gives them greater control to enhance their performance, but it also calculates the optimum mix of resources and fuels. So it helps the university’s miniature utility company satisfy demand at the lowest possible cost.

For more information, search keywords “ energy savings ” and “ building automation ” at www.automationworld.com.