PG&E Taps into Lighting Controls
Staff -- Consulting-Specifying Engineer, 9/1/2001 1:00:00 AM
Responsible for delivering energy to more than 13 million people in central and northern California, Pacific Gas and Electric (PG&E) is aware of the value of energy efficiency. This cognizance has led to attempts by the utility to limit its own energy consumption, including a recent lighting and controls retrofit in the PG&E distribution center, a 125,000-sq.-ft. warehouse in Fremont, Calif.
During the work week, the distribution center operates around the clock, providing the utility's branches with materials and supplies. To reduce lighting usage, existing high-intensity discharge (HID) lighting was replaced with T5 fluorescents. In addition, the company deployed an integrated series of various lighting controls.
"By selecting a number of different lighting controls, we were able to use the control technology that was best suited for each type of space," says Mike Smith, the facility senior project manager.
The controls include an exterior lighting-control panel, passive occupancy detectors, ultrasonic occupancy detectors and digital time switches.
For controlling the warehouse's rack aisleway lighting, the project leaders chose passive infrared (PIR) occupancy sensors. By selecting a specialized aisleway lens, the sensor's coverage was defined to avoid false triggers by employees in adjoining aisles. The project team also decided to equip each fixture with individual sensors, with time delays set for 10 minutes, to ensure adequate coverage. PIR sensors also control lighting in main and cross aisles, with longer time delays of 30 minutes, for adequate illumination in these higher-traffic areas.
For controlling lighting in the shipping and receiving area, the project team used the exterior lighting-control panel combined with low-voltage digital time switches. While the panel ensures that lighting is off during non-work hours, the switches provide a manual override for workers entering or exiting the areas during atypical hours.
In addition, the project team found that some other types of lighting controls were better for portions of the facility. For instance, office storage spaces were equipped with switches set at 15-minute time intervals, so that employees entering the area can easily activate the push-button switch for lighting when retrieving supplies or filing documents.
Completed late last year, this project has already led to some impressive results, with PG&E estimating that it has reduced its lighting usage by 54%. Overall, the company has reduced the facility's total electrical load by 33%.
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