Voltage reduction units on fluorescent lighting circuits are a proven energy saver. Savings of 20% to 30% are achieved, with around a 10% loss in light levels.
Voltage optimisation units are installed at the switchboard on lighting circuits, and work by supplying mains voltage to the lights when they start up, then dropping the voltage down to 190 to 200 volts 2 or 3 minutes later after the lights have largely warmed up. At a lower voltage magnetically or iron core ballested fluorescent ligths use less energy. If there are multiple light switching points on the voltage optimisation circuit, each time a new set of lights is switched on a good voltage optimisation unit should detect this and increase the voltage back to mains level so the lights just switched on can start. Then the voltage will drop back again after 2 or 3 minutes to the 190 to 200 volt level. When switching occurs light levels go up and down as the voltage reduction cuts in and out.
Voltage optimisation is a relatively low cost measure appropriate for areas with large banks of magnetically ballasted fluorescent lamps that are on for long periods of time. In this case the payback is fast. It doesn’t work on electronically ballasted fluorescent lights, including T5 lights.
Is voltage reduction appropriate for office lighting? Yes, it will work in large open plan office area, where the lights need to operate all day. But if there are small offices with lights that are frequently switched, or if occupancy sensors are used, then occupants may become annoyed with the change in light levels as the voltage reduction circuit cuts in and out. Additionally if the wiring diagrams are wrong, low voltage may inadvertently be supplied to other equipment that doesn’t appreciate the low voltage.
I once recommended voltage optimisation for a large office, mostly open plan, and 16 units were installed. Unfortunately the electrical wiring diagram wasn’t correct, so on installation the refrigeration compressor on the cool room supplying the staff canteen failed, as it was wired into a lighting circuit. With a lot of food wasted over the weekend and a $2,000 plus repair bill for the compressor the project didn’t get off to a good start. There were then issues with staff getting annoyed from changing light levels as lights were turned on and off in adjacent small offices and meeting rooms on the same lighting circuits. And over a period of three years four of the sixteen voltage optimisation units failed. So personally, as a result of this bad experience, I now tend to look for alternatives to voltage optimisation in offices.
On the other hand I know of a printer which installed voltage optimisation and has been very happy with the results.
Alternates that can be considered to voltage optimisation are delamping and using reflectors, which can lead to larger any savings and doesn’t have any of the switching concerns.
Car parks are often fitted with voltage optimisation equipment. New LED technologies, with inbuilt occupancy sensors, such as the Australian designed Chameleon, can however provide much larger energy savings with a reasonable payback.