Fluorescent Lighting 101
If you have spent any time researching florescent lighting solutions, it probably didn’t take long to find conflicting information about florescent fixtures, ballasts, and lamps. If you have met with a traditional lighting retrofitter or two, chances are that you may be confused by all of the claims of energy usage and energy savings calculators. We have condensed some guidelines to help reduce the confusion.
- Wattage Ratings – All fixtures are not created equal. Not only does quality vary dramatically between different fixtures, but Wattage also varies significantly. It is important to note that the ballasts inside of fixtures have a ballast factor that determines the amount of energy used and therefore the amount of lumen output of the lamps. A ballast factor of less than 1 will reduce watts used as a percentage of the rating for the lamps and at the same time reduce lumen output. A ballast factor of more than 1 will increase watts used as a percentage of the rating for the lamps and at the same time potentially increase lumen output. Another way to compare electrical efficiency of a fixture is to determine lumens per watt (LPW or lm/W). To determine a system’s efficacy, divide its lumen output by its rated imput wattage.
- Lumen Output – Standard T5, T8, and T12 lamps have very similar lumen output ratings of just under 3,000. Even though lumen output is similar, the resulting light and energy usage is quite different. This is a function of lamp diameter. Because smaller diameter lamps have less surface area they are actually much brighter. This explains the natural progression from the 1 ½” diameter T12 lamps to the 1” diameter T8 lamps and finally to the 5/8” diameter T5 lamps. Even though lumen output is similar, a T5 lamp is approximately 1.6 times brighter than a T8 lamp while still using less energy.
- Mean Lumen Output – In simple terms this represents lumen output over the life of the lamp. Lumen output decreases over the life of all florescent lamps, so it is important to know how much light they will produce over time rather than just looking at initial light output. T5 lamps maintain approximately 95% of their initial lumen output over the life, while T8 lamps maintain less than 90% and T12 lamps maintain less than 80% of their initial output.
- Heat – It is important to understand the effect of heat on operation of florescent fixtures. T12 and T8 fixtures are tested and rated based on operating conditions at 77degrees farenheit, yet we know that most of these fixtures operate at a much higher temperature. The heat not only increases energy usage of the fixture, but it also decreases the life of the lamps and ballasts. Our testing has proven over and over again that in most cases T12 and T8 fixtures are not operating according to their ratings. Because the T5 adapters are using less energy and producing more light, they are burning at a much lower temperature, therefore allowing them to operate at or below their rated energy usage, and extending the life of the ballast and lamps.
Remember, field testing will clear up much of the confusion related to lighting retrofits. It’s time well spent to ensure maximum return on investment and satisfaction with the actual lighting results.