Jim Brodrick on LED Linear Replacement Lamps
Guest Post by Jim Brodrick, Department of Energy
[Recently], I wrote about LED linear replacement lamps and told you about an upcoming webcast on the subject. The webcast, entitled “LEDs for Interior Office Applications,” ended up drawing nearly 800 attendees and prompting nearly a hundred questions from the audience – far more than could be answered in the allotted time. The questions that weren’t addressed during the webcast will be answered soon on the website – something we only do when the topic is an especially hot one.
Why is this such a hot topic? Because of the tremendous popularity of recessed “troffer” fixtures with 4′ fluorescent T8 lamps in commercial and institutional lighting applications. There are tens of millions of these fixtures in use in this country alone. That – and the claims of many manufacturers – has a lot of people wondering whether LED linear replacement lamps truly are a “drop-in” equivalent to fluorescent T8s that can be substituted right off the shelf for big-time energy savings.
As I made clear last month, the short answer is a resounding “no!” DOE’s CALiPER program has tested a dozen different LED T8 replacement lamps to date, and the bottom line is that they simply don’t perform as well as their fluorescent counterparts – which, in addition, are much less expensive and have fairly long lifetimes. The LED T8s we’ve tested have fallen short by a significant margin in terms of light output, system efficacy, fixture output, luminaire efficacy, and CRI. And although they scored higher than fluorescent T8s in terms of average fixture efficiency – thanks to the directionality of LEDs, which results in less light lost inside the fixture – this wasn’t enough to compensate for their much lower light output.
What this means is that, amidst all the heated market activity, buyers and specifiers need to be very careful when it comes to LED T8s. That’s why DOE has just published a fact sheet on the topic, which serves as a useful tool to help buyers cut through the hype and get to the heart of the matter. The fact sheet lists what they should be asking from manufacturers (e.g., at least 6,000 hours of lumen maintenance testing on the full lamp), as well as what level of product performance should be specified for replacement applications (e.g., initial minimum lamp light output of 2,700 lumens). The bottom line is that to provide equivalent light to fluorescent T8s while keeping power input for these products at their current range (15-20 watts), LED T8s will have to become two to three times more efficacious than they currently are.
Those of us in DOE’s SSL program have a thin line to tread in nurturing the technology so that it can fulfill its energy-saving potential. We’re neither cheerleaders nor policemen. Rather, we’re more like baseball umpires, in that we observe what’s going on, take an objective point of view, and simply “call ‘em as we see ‘em.” And when it comes to LED linear replacement tubes, the pitchers have been missing the plate by a wide margin (forgive me for having baseball on my mind – it’s April!). The new DOE fact sheet is intended not only to keep all those “batters” out there from swinging at a bad pitch, but to encourage the pitchers to improve their aim and start throwing strikes – so that we can all “play ball!” and save energy.