Controllable Ballast Retrofit Using Load-Shedding and Daylight-Harvesting Strategies Reduces Lighting Costs By 76%
According to ELI president and CEO Joseph F. Desmond: "load management, which is the modification of energy usage patterns, historically has focused on interruptible loads such as air conditioners and hot water heaters. But when incorporated as a building lighting strategy, facility managers can monitor demand or energy prices as they rise and then gradually dim down the lights by up to 30% while remaining unnoticeable to the occupants." Desmond adds that this project is one of the first in the country to employ the lighting load management strategy in this way. "Integrating daylight harvesting was an important part of the overall strategy, and the combined results were phenomenal." He further adds that lighting load management has emerged as a dynamic proven energy strategy to dramatically reduce lighting energy costs.
Lighting Load Management as a Breakthrough Application
According to Desmond, lighting load management is the first application to pay off big for businesses everywhere, particularly with the onset of deregulation. The Alachua County project, while not in a deregulated area, is still saving the county building 34% of its total electric bill. Further, the project is expected to pay for itself in about 2.5 years. This quick return of investment represents less than half of the payback initially anticipated by county officials. A 39% internal rate of return on the project is anticipated, despite a low 6.2-cent per kilowatt-hour average price of electricity. Energy reduction due to the project totals 265,000 kilowatt-hours annually in this part of Florida. County Energy Management Specialist Charles Balanis contends that his results show that the program is working. He says that "we're seeing tremendous drops in kilowatt-hour consumption. People are completely unaware the lights are gradually dimming and I get to watch the energy savings."
The savings are due to a buildingwide retrofit in which 406 drop-ceiling lighting fixtures with standard magnetic ballasts were equipped instead with ELI controllable electronic ballasts, making it possible to dim lights when necessary, increase lighting when needed, and control and track the entire operation by computer. In perimeter areas, lights are dimmed in a daylight harvesting strategy as photosensors control light output based on increases in daylight. All of the lights are connected to a load-shedding system that is programmed to dim during periods of high demand. And cost savings rapidly accumulate, since in most buildings of this type, lighting typically represents 30%-50% of the total electric load.
ELI Technology Saves 50-60% Over Existing Systems
According to Desmond, "a standard lighting retrofit, using existing T8 lamps and fixed-output electronic ballasts, reduces lighting energy costs an average of 25% compared with original T12 lamps and magnetic ballasts. Using technology developed and designed by ELI as part of a larger lighting-load management strategy, you can expect savings of 50-60% over existing systems."
The environmental impact of the project is equivalent to removing 186.93 tons of carbon dioxide (CO2), 1.59 ton of sulfur dioxide (SO2), and 0.66 tons oxides of nitrogen (NOX) annually. This is a total of 189.18 tons of contaminants removed from the air each year.
In the Alachua County installation, the 34,000-square-foot, 20-year-old three-story brick building houses some 70 employees. The building was equipped with 406 four-lamp prismatic lens fixtures using standard magnetic ballasts and a mix of F40T12 and energy-saving T12 lamps. This included about a half-dozen three-lamp open-cell parabolic lens fixtures with exposed T12 lamps. All three floors consisted of banks of open cubicles with private offices around the perimeter. During the retrofit, ELI's two-lamp dimming ballast were installed in each of the 406 fixtures and the T12 lamps were replaced with T8s. In some areas, fixtures were delamped and specular reflectors were installed. This brought the wattage down from a range of 158-174 watts per fixture to an average of 58 watts per fixture.
A Variety of Control Strategies Were Used
Ultimately, several control strategies were implemented in the building. These included occupancy sensing devices, manual tuning, daylight harvesting, and lighting-load management. The lighting-load management was controlled by an ELI Envoy Lighting Load Controller. This unit is a smart-lighting-load controller that provides gradual, unnoticed light level reductions at critical times. This feature permits significant power reductions with out compromising lighting levels. Watt Stopper occupancy sensors for on/off control were used in wall switches for every office and in the ceiling above open offices and cubicles. Some of the offices were also fitted with manual dimmers, and perimeter offices with windows received photosensors for daylight harvesting. Still, every ballast in the building was connected to an Envoy Lighting Load Controller.
Business hours in the facility run from 8:00 a.m. to 5:00 p.m., Monday through Friday with up to six hours of occupancy during the weekend. However, at least 80% of the lighting had been running 24 hours a day prior to the retrofit. According to Balanis, "we didn't have a building management system on the lighting, I don't think they even thought about turning the lights off." Following an on-site survey and audit, Balanis chose ELI due, in part, to the powerline carrier (PLC) compatibility offered by ELI's controlled lighting system. Balanis has planned for a PLC system to control other loads in the future.
Decision Resulted in 2.45-Year Payback
According to Balanis, the other concerns were reliability, ballast factor and the realization of the promised energy savings. Balanis adds that the decision was an easy one because "the worst case scenario of swapping out the existing standard magnetic ballasts for dimming electronic ballasts would still yield substantial savings." The project was approved by the Board of County Commissioners during the budget process based on an expected four-year to six-year total return on investment. According to Balanis, "the savings from dimming, which bring payback down to 2.45 years, is an added bonus that will provide significant savings to the taxpayers not only now but for years to come."
ELI Equipment Allowed for Easy Installation
The ELI controlled lighting system was installed by Chem Light Plus of Gainesville in what Chem Light's Vice President Douglas Robinson terms "an easy installation." In addition, savings on the project were immediately evident. Consumption dropped 21,600 kilowatt-hours in the first month compared with the same period the previous year. Additionally an even more dramatic reduction of 32,000 kilowatt-hours was recorded the month following the addition of the lighting load controllers.