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LED vs. Fluorescent: Are Linear LEDs Ready to Replace Your T8s?
Now that the most common lamp in commercial buildings, the 32W linear fluorescent T8, is no longer manufactured, facilities managers are faced with a tough choice when it’s time to replace existing lighting.
Non-compliant lamps will still be available for a while. However, as the existing supply dwindles, you’ll eventually have to switch to fluorescent T8s that comply with federal efficacy standards or upgrade to LED lighting solutions.
LED vs. Fluorescent Lighting
All major lighting manufacturers produce linear fluorescent lighting solutions that comply with the Department of Energy’s lighting efficiency requirements. The new fluorescent tubes consume 28W instead of 32W but deliver the same amount of light that you’re used to. Alternatively, you can use energy-efficient lighting that consumes the same wattage but delivers more lumens per watt.
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If your budget allows, however, it might be worth the upfront investment to make the switch to LEDs. You’ll avoid the periodic updates to fluorescent lamp standards and save money in the long run. An LED lighting system delivers many more lumens per watt than comparable fluorescents do. An LED T8 tubelight meant to replace a 32W fluorescent consumes 15-18W.
How to Convert Fluorescent to LED
A recent field test by the California Lighting Technology Center at the University of California, Davis, compared LED retrofit lighting solutions meant to replace linear fluorescents. Sponsored by Pacific Gas and Electric Company’s Emerging Technologies Program, it examined a cross-section of 13 linear LED lighting solutions against a standard linear fluorescent in a bare-lamp strip fixture, a suspended pendant and a surface-mounted wrap. The LEDs in the study covered all five types available on the market:
Type A: These linear LEDs have an internal driver that operates on the ballast left behind by the linear fluorescent. Test results for Type A lighting solutions were all over the place in regards to light output and system efficacy for lamps operating in the same fixture and on the same ballast. But Type A products generally delivered less light than the fluorescent baseline in all three fixtures tested. The LEDs did outperform the fluorescent tube in system efficacy, however.
Type B: The internal driver of these LEDs must be connected directly to line voltage. Type B lamps also provided less light than the fluorescent baseline to the tune of a 13-35% reduction in light levels. In the pendant fixture, the light output was 17-51% lower. The LEDs performed best in the wrap fixture because its elevated temperature degraded the performance of the fluorescent. Yet the LEDs ultimately still delivered 2-31% less light in the wrap.
Type C: These LEDs have an external driver that replaces both the lamp and ballast of its linear fluorescent predecessor. They performed the best out of all products tested, delivering 10% more light than the fluorescent in the wrap fixture, 10% less in the pendant and about the same amount of light in the bare lamp fixture. Type C’s successes are credited to the external driver as it’s often optimized for that particular linear LED lighting solution, the study notes.
Types AB and AC: These hybrid lighting solutions (also known as dual-mode products) can perform under multiple scenarios (e.g. with a fluorescent ballast and when the ballast is replaced with a compatible LED driver). Light output for Type AB products didn’t vary significantly between operating mode A vs. B. Of the two Type AC LEDs tested, one showed notably increased light output when operating as Type C.
LED Lighting System Recommendations
“Based on project test results, it’s evident that linear LED lamps marketed to replace standard 4-foot linear fluorescents cannot compete in terms of total light output,” the researchers wrote. All tested LEDs delivered higher efficacy than the fluorescent baseline. However, the study explains that overall energy savings are delivered in part by reducing the light output, not just by reducing power.
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Type C lamps tended to deliver the best results in both light output and system efficacy, the researchers say. This makes them the best alternative for fluorescent replacements. Type AC lamps operated in Type C mode can help bridge the gap during a retrofit.
“Type AC lamps, when paired with recommended drivers, consistently deliver light levels that are generally equivalent to or better than the selected fluorescent system used as a baseline for comparison,” the study explains. “Initial installation is as quick as a Type A. When fluorescent ballasts fail, they can be replaced with LED drivers that will maximize light output and energy savings.”
The study also offered these tips for making the most of any project to convert fluorescent to LED:
- Use recommended controls. Extensive compatibility testing showed that most products suffered severe degradation of performance whenever they were paired with non-standard ballasts and drivers. Use ballast compatibility information whenever it’s available to make sure your LEDs last as long as they’re supposed to.
- Never use a driver that isn’t recommended by the lamp manufacturer. Most of the Type C LEDs only lived up to promoted claims when operated on the manufacturer-recommended product. Some incompatible lamps and drivers produced visible negative results. In other cases, the system appeared to be delivering increased light output even though it was actually being overdriven, which will shorten the life of the lighting system.
- Don’t use linear LEDs in delamped configurations. Delamping resulted in considerable performance degradation for most of the tested lamp, ballast and driver combinations. “Few manufacturers include delamping information on product specification sheets,” the researchers state. “Manufacturers should explicitly call out information on delamping and bring that information out of the footnotes and into the main body of publications.”
Read the rest of the study: cltc.ucdavis.edu.
Even more: How to Manage Your First Lighting Retrofit
Janelle Penny (email@example.com) is Senior Editor of BUILDINGS.