Load Shedding Control by Wattstopper

This is a good white paper by Wattstopper.  Let me know if you have any questions.
Shad Asebrook
Sesco Lighting
615-830-1655 

Link to Wattstopper PDF

Solutions for Load SheddingWith energy alerts on the rise and demand charges increasing, load shedding has become an important lighting control strategy. Because many lighting loads are non-critical, they are prime candidates for load shedding along with other non-critical building loads.

Daylighting Controls
Load shedding with daylighting controls is a natural, automatic process. Because high energy demand often occurs at the same time daylighting potential is the greatest, the natural consequence of using daylighting controls will be to reduce lighting as the level of daylight increases and becomes adequate to replace artificial lighting sources.

With continuous dimming products, such as The Watt Stopper’’s LightSaver LCD control, users can define the minimum light level they want to maintain throughout the course of a day, and the dim- ming controls will adjust artificial lighting based on this setpoint and the available daylight contribu- tion. When daylight is adequate, lights will be dimmed and when daylight diminishes, artificial light levels are raised. The multi-zone option of the LCD enables the use of independent dimming controls in different areas of a building space, such as an open office area, where daylight levels may differ. One lighting zone, nearer to windows or skylights where daylight levels are higher, may dim artificial light- ing earlier in the day and to lower levels than in another lighting zone that is located further from the daylight source and receiving a smaller daylight contribution.

ON/OFF switching controls, such as The Watt Stopper’’s LightSaver LCO control, are also effective load shedding tools. Compatible with all lamp types, ON/OFF controls turn lights off when the daylight contribution reaches a user-defined level. Multi-zone controls enable bi-level, or stepped dimming, which can be particularly effective as a load shedding strategy. Most commonly, individual lamps with- in a multi-lamp fixture will be grouped into different zones; the inner lamps in three-lamp fixtures in one zone and the outer two lamps in a separate zone. The lighting in each zone is turned off once day- light levels reach a defined setpoint. Usually, the zone comprised of the inner lamps will be turned off first, reducing lighting by one-third. Later in the day, when the daylight contribution increases, the other lighting zone can be turned off. For more aggressive load shedding, the sequence can be reversed, to shed two-thirds of the lighting load earlier in the day.
The Watt Stopper Application Bulletin
Lighting Control Panels
Another effective tool for achieving load shedding is the use of lighting control panels. Panel prod- ucts perform load shedding by turning off non-critical loads during peak times.

For instance, users of The Watt StopperComplete Control panel products can employ a prepro- grammed control scenario to shed non-critical lighting loads. This could be half of the lighting in a "bi-level" controlled space. Under such a scenario, occupants are "locked out" from exercising local overrides via switches or telephone contact with the system. This control scenario can be pro- grammed to operate during daily intervals when peak loads are most likely to occur, or when a facility historically attains its highest demand. This strategy can also be invoked under energy shortage alerts.

Specialized Load Shedding Solutions
Additional automated load shedding solutions include teaming The Watt Stopper Automatic Relay Pack (ARP) with the Telephone Switch Module (TSM). Non-critical, sheddable loads are connected to one relay on the ARP-Net, while critical, non-sheddable loads are connected to the other relay. The TSM is installed on the ARP-Net network. During a power alert, a call into the TSM from the facility manager will turn off the relay with non-critical loads. The ARP’s lock-off capability ensures that once the signal from the TSM is received, lighting or other loads (i.e., HVAC, fans, etc.) immediately shut off, and that ordinary occupant overrides are not available. To restore the loads, the facility manager makes only a quick call back to the TSM and follows a sim-
ple push-button sequence.