May 1997 Volume 3 Issue 10
High-Efficiency Fluorescent Lighting
The field of fluorescent lighting has experienced big changes recently. First, there have been regulatory changes. As part of Canada’s national commitment to reduce CO2 emissions, the Energy Efficiency Act made obsolete many standard-wattage fluorescent lamps. It is no longer possible to import into Canada or ship between provinces such fluorescent lamp classics as the 4-foot 40-watt cool-white lamp (F40CW) or the 8-foot 75-watt cool-white slimline lamp (F96T12/CW).
Second, there have been technological changes. New tri-colour phosphors were developed that are
· more energy-efficient,
· render colours better, and
· maintain higher light output over time
than halophosphate phosphors such as Cool White and Warm White — the industry standard for decades. In addition, electronic ballasts are replacing coil-and-core electromagnetic ballasts, giving fluorescent lighting an additional efficiency boost. Finally, there is a growing array of compact fluorescent lamps. These screw-in and plug-in units can replace incandescent bulbs in many situations, cutting electricity expense by more than 70 per cent.
“My building is full of 40-watt cool-white fluorescent lamps, what do I do when they burn out?”
One approach is to install those 34-watt cool-white lamps that have been around for a decade or more under tradenames such as Watt-Miser, Super Saver, and Econowatt. These lamps are still being sold. Although slightly more expensive than the discontinued 40-watt lamps, the price difference is more than paid back over the life of the lamp by the electricity savings resulting from the lower wattage.
Compact fluorescent lamps are now available in higher wattages and an ever-increasing range of styles.
While these 34-watt lamps use 15 per cent less energy than 40-watt lamps, they also produce 13 per cent less light. This is not normally a problem, but if it is — or if you need better colour rendition, or lamps that stay bright longer — consider relamping with one of the new tri-colour-phosphor T12 lamp varieties. Four-foot long, 1.5-inch diameter (T12) direct plug-in replacement lamps using these new phosphors are available in 40-, 34-, and 32-watt models. The table on the next page summarizes a few of the options. All of the types mentioned — except the 40-watt cool-white — are currently available.
There are similar replacement options for many other discontinued lamp types.
THE T8 CHOICE
T8-series fluorescent lamps are 1 inch in diameter rather than 1.5 inches. They employ the new tri-colour phosphors, and they operate at maximum efficiency when used with high-frequency electronic ballasts in a performance-coordinated T8 lamp-ballast system. (T8 lamps cannot be used with T12 ballasts. )
Electronic ballasts produce more efficient lighting for two reasons. First, their internal energy loss is lower than that of traditional coil-and-core ballasts. Second, electronic ballasts excite the phosphor more continuously. Traditional ballasts produce 120 pulses of current every second, and the phosphor’s light output drops drastically between pulses. High-frequency electronic ballasts produce tens of thousands of pulses per second, and phosphor light output drops less than 2 per cent between pulses. This high-frequency excitation also eliminates the strobe or flicker effect that fluorescent lamps exhibit when used with electromagnetic ballasts.
How does the electricity expense for 32-watt T8 lamps and electronic ballasts compare with 34-watt cool-white lamps and standard ballasts? We’ll assume that the ballast factor of the electronic ballast has been chosen to make the light output of the two systems the same. Under these conditions, the electricity savings will range from 28 to 38 per cent. (For 1-lamp fixtures: 38%. For 2-lamp fixtures: 28%. For 4-lamp fixtures: 29%.)
For example, let’s assume that a workroom is illuminated by 24 flourescent fixtures, each containing four 4-foot lamps. Let’s also assume that the lights are on for 3000 hours per year. If electricity costs $0.10 per kilowatt-hour, the yearly cost of electricity for the 34-watt lamp and standard ballast system would be $1130.40. The electricity cost for the T8 system would be $806.40. The annual savings would be $324.00, which is 28.6 per cent.
THE COMPACT FLUORESCENT CHOICE
Incandescent bulbs cost little to buy. But they last only 1000 hours and — for the amount of light they produce — consume a great deal of electrical energy. Most of the compact fluorescent lamps sold to replace incandescents have a 10,000-hour life, and while they are proportionally more expensive to buy, their much lower operating cost makes them a bargain. The table below tells the story:
The figures in the column at the far right are for one lamp of the indicated wattage. They show what the electric bill savings would be during the 10,000 hour operating life of the lamp at an electricity cost of $0.10 per kWh.
For more information about energy-efficient lighting, call Ron Estabrooks or Mike Proud at
1-800-236-5193 (toll free). Request the free booklet Commercial Lighting Efficiency.