Replacing existing fluorescent lamps with LEDs of the same size and form factor is becoming an increasingly viable retrofit option for their potential to reduce energy use and improve indoor lighting quality.
by Stan Walerczyk, HCLP, CLEP
You have probably walked through numerous open offices and saw one, two or maybe all fluorescent lamps twisted out or removed in various 2×4 troffers. This is because some workers, especially if they are on the younger side, doing mainly computer work, want less light, because less glare on computer screens. But there are often workers, who may be older and/or doing paper or other tasks, who keep all of the lamps working. With fluorescent lamps, especially driven by parallel-wired ballasts, this works quite well.
But most LED troffers and troffer kits, even if they are dimmable, can cause problems, because various office workers will probably not agree on any one light level in the open offices. I retrofitted 2×4 parabolic troffers, which with all three fluorescent F32T8s provided about 5000 out of fixture lumens with 25W LED troffers, which provide about 2500 out of fixtures, and numerous office workers complained about too much light, because they had zero, one or two T8s working before. That was in the Pacific Northwest where the Lighting Design Lab has no minimum lumen requirements, so there were rebates. In other parts of the country, the DesignLights Consortium mandates at least 3000 out of fixture, which can make the problem worse.
There are various LED solutions.
The best and easiest may be using task ambient lighting with a relatively low ambient light levels and task lights when people are doing other than computer tasks. I often aim for 10 – 20 footcandles from the ambient lighting, which provides plenty of light for walking around and doing computer tasks. This can usually be attained with about fixed 15W or 20W LED troffers or troffer kits. Each of these will provide about 1500 or 2000 out of fixture lumens. Again, these are not approved by DesignLights Consortium, so there may not be rebates. My favorite task light is the dimming and CCT or Kelvin changing Prism – PlanLED TL7000. Depending on quantity, they may cost $80 – $120 each.
There are advanced wired and wireless complete building systems that can be programmed to individually control each digitally addressed LED troffer or troffer kit. But this can be quite expensive, like up to $100 per fixture including all of the parts, labor, commissioning and software licensing fee.
Cree’s SmartCast and Philips’ SpaceWise systems allow a TV style remote control to be pointed at individual troffers to adjust light level from each troffer. But this can also be quite expensive. At least one manufacturer is considering a low cost bi-level or tri-level dip type switch in each troffer or troffer kit.
A number of LED lightbars could be removed from troffers; LED lightbars are much better than LED T8s. Cree UR, RedBird StripIt Kits, LED Living Technology Claris, and Deco Lighting Linea are examples.
Some LED T8s, also called TLEDs, could be removed, but please avoid LED T8s for multiple reasons.
Although not LED, high performance fluorescent T8s and high performance parallel wired electronic ballasts can be a very good solution. A lot of this also applies to 1×4 troffers, 2×2 troffers, wrap-arounds and other fixture types.
It is tools like this that can improve end-customers’ satisfaction with lighting retrofits, which in turn improves the image and business of distributors and contractors alike.
Walerczyk is principal of Lighting Wizards, an independent energy efficiency consulting firm. He has over 25 years of lighting experience including distribution, maintenance, retrofit contracting, and industry research. An Association of Energy Engineers-Certified Lighting Efficiency Professional, he also holds a Lighting Certified designation from the National Council on Qualifications for the Lighting Professions. He can be reached at firstname.lastname@example.org.