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By James Piper, P.E.
Power & Communication Article Use Policy
Utilities structure demand response programs to give incentives to customers to reduce their electricity demand at times of high energy use so the utility can prevent service interruptions or to help the utility control its generation costs. Incentives for facilities can come in the form of rebates for achieving specified levels of demand reduction or lower utility rates.
The most common loads in a facility targeted by demand response programs are the big energy users — chillers, air handlers, pumps, elevators, and lighting systems. When the utility sends a signal identifying a demand reduction event, maintenance and engineering managers can reduce electricity loads manually, or they could use their BAS to reduce these loads.
System operators can increase chilled-water-supply temperatures slightly to reduce the electrical load on the chillers. They can increase air-handler supply temperatures, and in variable-volume systems, they can throttle back supply air quantities.
If pumps have variable-frequency drives (VFDs), operators can run them at reduced speeds. In buildings with banks of elevators, operators can temporarily shut down one or more of the elevators. They also can temporarily shut off portions of lighting systems.
For managers taking these actions, the goal is to reduce electricity demand without causing major disruptions to facility operations. In most cases, operators restore the affected loads when the demand reduction event is over.
One problem managers face when trying to reduce loads without disrupting operations is that they have limited options. Operators cannot reset all chiller systems easily, and resetting air-handler supply temperatures often requires resetting a number of different thermostats, many of which are behind locked covers. Shutting down lighting systems or even portions of them also could result
in safety and security problems. Fortunately, new technology is helping managers solve many of these issues while expanding options.
Demand Response: Strategies and Tactics for Success
VFDs Expand Load Capability for Demand Response Programs
Facilities With BAS Have Advantages for Demand Response Programs