I recently wrote an article for TED Magazine about load-shedding ballasts, available online here.

Load-shedding ballasts were installed at the Spence School in New York City in a demonstration project funded by NYSERDA. The ballasts are linked to a building management system, allowing the school to reduce lighting energy consumption by 30 percent when desired. At the click of a button on a laptop or mobile phone, Spence School can temporarily reduce demand by 261 kW during emergency grid events. “The success of this project shows the huge potential of our new Demand Response Platform,” says Stephen Lynch, president of ACE Energy Company, Inc. “This technology will not only reduce Spence School’s energy cost but will also make the world a greener, more energy-smart place.” Photo courtesy of OSRAM SYLVANIA, Inc.

A building’s demand for electric power is the sum of the power required to run its electrical equipment in operation at any given time. Demand rises and falls as equipment is turned on and off. Peak demand is the highest level of demand over a given period. It’s the most expensive power the utility must produce, and these high costs are passed along to customers. Demand charges can represent 25% of a commercial building’s electric energy costs.

To encourage its customers to reduce demand during peak demand periods, utilities, independent system operators (ISOs), and other power providers are offering demand-response programs that provide financial incentives to building owners who agree to curtail load on request—either at scheduled times or during an emergency.

Building owners can significantly reduce their electric utility costs, therefore, if they can curtail load on a schedule, in response to price signals, or on demand by a utility—a strategy called load shedding. When it comes to lighting, this means switching or dimming. To address this need, the major manufacturers have begun introducing load-shedding ballast products.

Load-shedding ballasts:

* Provide a way to reduce input power upon an external demand
* Can be instant-start or program-start
* Can be bi-level switching, bi-level dimming or continuous dimming

Dimming or switching/ Generally, dimming is preferable to switching in occupied spaces in which users perform stationary or critical tasks—i.e., where changes in light output should be unnoticeable to a high degree.

How low can light levels go before occupants object? In developing a prototype for load-shedding ballast technology subsequently commercialized by lamp and ballast maker OSRAM SYLVANIA, the Lighting Research Center studied the question and concluded that they could dim the lamps by as much as 40% for brief periods without upsetting 70% of the building’s occupants or hindering their productivity. LRC studies also showed that nine out of 10 occupants accepted the reduction when they were told that it was being done to reduce peak demand.

Solutions are generally classified as low voltage (respond to a control signal from low-voltage wiring) or line voltage (respond to a control signal from line-voltage wiring). Low-voltage solutions enable integration of the ballast with other control strategies such as daylighting control and scheduling. Line-voltage solutions are well suited for retrofit because no low-voltage wiring needs be installed, just a signal transmitter.

You can read the entire article here.

Here are a few additional notes not covered in the online article:

Low-voltage solutions, both analog and digital, include SYLVANIA’s QUICKTRONIC POWERSENSE ballasts (continuous dimming), GE’s UltraStart (continuous dimming) and UltraMax Load-Shedding Instant Start ballasts (bi-level or 0-10V dimming ballast, 1.18 to 0.71 ballast factor, a 40 percent reduction in both power and light output), Advance’s Mark 7 and ROVR ballasts (continuous dimming), and Universal’s SuperDim, DaliPro and AddressPro (continuous dimming) and Ballastar ballasts (step-switching and dimming).

Line-voltage solutions, ideal for retrofit, including Universal’s DemandFlex ballasts and Demand Control Lighting (DCL) control system (enabling individual circuit control so that the load on some circuits can be reduced further than on other circuits—or turned off), Advance’s Mark 10 ballasts (continuous dimming), GE’s UltraMax Bi-Level Switching or 0-10V Load Shed Instant Start ballasts (step-switching from 1.18 to 0.71 BF), and SYLVANIA’s PowerSHED ballast (step-dimming with a one-third reduction in power, operates with a control signal transmitter, located at the control panel, capable of serving hundreds of ballasts).

Craig DiLouie

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