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The energy crisis in the early 2000s highlighted the fragile state of the nation's power infrastructure. High demand quickly outpaced available energy, leaving many people in the dark during the hottest days of the year. The rolling blackouts continued for months in some parts of the country, and many scientists and researchers searched for ways to curtail energy needs in times of emergency—a process referred to as load shedding or demand response. The curtailment saves the power grid from overloading, preventing widespread blackouts and broken equipment that can prolong the crisis.

HOW IT WORKS

The load shedding process is simple in theory: The utility company or demand response service provider sends out an alert (usually via the Internet or wireless signals to an automated system within the building), and either the building engineer or the building automation system responds by adjusting air conditioner and heater set points, shutting off auxiliary equipment, and stopping other nonessential systems. Power companies provide incentives to building owners for participating in several ways, depending on the severity of the crisis.

Some programs pay for new equipment or offer rebates, others pay for the amount of energy use reduced (New York's Con Edison, for instance, pays $0.45 per kilowatt-hour saved under its emergency demand response program), and a few programs give a preferred rate but charge penalties for energy use over a certain amount during peak hours. Most utilities make a combination of these offerings available, allowing customers to participate in different ways. For example, some load shedding programs provide as much as a day's notice before the power supply needs to be limited, while others may alert a building only an hour or two in advance. Also, some programs might require a building to comply with the load shedding for as long as one workday or only during peak hours, usually at midday.

SHEDDING THE LIGHTING LOAD

Lighting, however, has played a limited role in this process because of the expense and complexity that can be involved in dimming lights to save energy. Many lights used commercially today cannot be dimmed, even with the presence of lighting control systems, because the fixtures would need to be upgraded to utilize dimming ballasts. While some new buildings have lighting control systems, many older buildings might need to be rewired but all would have to replace a large portion of the lighting equipment at great cost prior to being able to install a control system. “The building engineers love simple and they hate variability or uncertainty, so if you bring a control system into a space for a retrofit that has a lot of questions: Will it be compatible? Will I need more wires? Will I need to interface with a complicated control box? People don't want to budget for the complicated controls and are reluctant to because they don't want to lose money on the job,” explains Jim Frey, Osram Sylvania's ballast product marketing manager. The other option is to shut the lights off completely, but working in the dark would have a negative effect on productivity.

This is where the Troy, N.Y.–based Lighting Research Center (LRC) at Rensselaer Polytechnic Institute stepped in. The LRC worked with the DOE on a project investigating step dimming for fluorescent lighting. LRC professor Andrew Bierman says they were able to dim the lamps and cut the power used by the fixtures, but it had few practical commercial applications. The one application they did see was to use the system for load shedding in office buildings, which became the focus of the LRC's new project. The prototype ballast developed by the LRC replaced most instant-start ballasts, which are used in 80 percent of fluorescent light fixtures. Because the technology the LRC developed amounts to reballasting, they saw it as great option for load shedding: building engineers are trained to install a new ballast, and the building owner could use the same fixtures already installed. By using a power line carrier, the ballast responds to a signal sent from the wires already in the ceilings, obviating the need for running extra wires to the fixtures or installing expensive wireless solutions. With the signal activated, the fluorescent lamps dim by 33 percent.

The LRC's system requires three steps: install the new ballasts; relamp the ballasts with compatible, highly efficient lamps; and hire an electrician to install the power line injector at the lighting control box or circuit breaker. The injector adds the signal to the power lines and can be controlled by a switch, plugged into a building automation system, or connected to the Internet to receive signals from the power company.

TESTING

Once the LRC saw the opportunity for this technology, it started research separate from its work with the DOE. Bringing on a few partners (including Osram Sylvania and Con Edison), the LRC took the next step in summer 2006 with its sponsor, the New York State Energy Research and Development Authority (NYSERDA). The LRC and NYSERDA tested the system at Con Edison's Rye, N.Y., headquarters, where they ran surveys and conducted studies of the environment created by dimming the lights to save energy. The system was activated six times, and the LRC evaluated the employees' responses to the new conditions. “The whole basis of this project is to achieve the demand reduction without infringing on the work environment,” says Con Edison lighting specialist Peter Jacobson. “Through a controlled dimming capability, this technology reduces the light to an amount where we feel that it doesn't take away from people's work conditions and their visual environment.” The LRC survey found that Con Edison's employees were not bothered by the dimming and that many didn't notice the change at all. On the whole, the employees encouraged the new system because it would help during a power emergency—which, in turn, could keep the lights on in their homes.

The LRC tapped Sylvania to create a version of the ballast that could go to market. They have worked together for the past two years to meet three challenges: make it affordable, make it easy to install, and make it minimally invasive to the end user. “This is a three-pronged effort here that was truly started as an idea in the lab,” Jacobson says. “The LRC asked, ‘What if we can do this? What if there were a product available that could talk through an existing lighting system and then reduce the amount of light as well as reducing the amount of power, but not disrupt the existing work environment?' The project went from there.” The end result is the now-available Powershed High Efficiency Demand Response Ballast from Sylvania, which Jacobson helped create.

Load shedding's proliferation will be encouraged by utility companies to help stabilize the availability of power, but all three groups involved in this project—the LRC, Con Edison, and Osram Sylvania—point out that it also is a great way for building owners to take control of their power usage. It presents a new option in controlling lighting's power consumption, which can account for almost 25 percent of a building's energy use.

This version of load shedding also is an attractive option for lighting designers working in existing spaces. The system allows an energy-saving feature to be introduced to existing environments without a large capital outlay, and with the incentives available from power providers it can pay for itself in fewer than three years.