By David Venhaus, Senior Solutions Specialist, Hubbell Lighting
Several challenges—performance, light quality, and initial cost —have prevented the wholesale adoption of light-emitting diodes (LEDs) in lighting, whether the application is a retrofit or new installation.
The performance part of the puzzle has been pretty much won by LEDs, with fixture efficacies exceeding even the best incumbent technologies by a minimum of 25 percent and in some cases more than doubling the efficacy of luminaires. Light quality also continues to improve.
The most exciting development is the rapid decrease in initial costs. Over the last five years, many of the more common applications like high bays and troffers saw massive price decreases, some by as much as 75 percent.
The evolution in the emitter package, particularly mid-power LEDs, specifically drove this decrease. If we rewind to 2008-2010, we see tremendous effort in one- to three-watt emitter packages. The effort was mostly focused on efficacy and extracting as many lumens from a single emitter package as possible. While this led to some impressive gains in performance, it did so almost to the point of becoming problematic in certain applications.
How so? In an outdoor application, where an individual beam-forming optic is placed over each emitter, the evolution was a luminaire designer’s dream. Suddenly, hundreds of lumens were available from a single-point source that, when paired with an optic, made a potent combination.
But in an indoor application, where reduced glare and a smooth-lit appearance was premium, this became a drawback. Suddenly only eight or 10 emitters were needed to make a 3,000-lumen 2×2 troffer. This put too few emitters too far apart behind the typical diffuser to allow for smooth delivery of light, leading to a “lumpy,” spotty, or pixilated appearance.
The fix was to put a less efficient diffuser over the emitters, killing of all those precious gains in efficacy, or using more emitters than required, driving up cost.
Enter the mid-power emitter.
Smaller, low-power emitters were gaining traction in television and other backlight units around this time. These emitters paved the way for the current generation of mid-power emitters that run at lower power levels (typically ¼ to ½ watt) yet still make substantial amounts of light. Today, these emitters deliver light at less than one-tenth the cost per lumen of their higher-power predecessors in 2008.
As the cost of these emitters plummeted, manufacturers leveraged lean manufacturing techniques that afforded them the opportunity to place hundreds of these emitters in a luminaire in a cost-effective manner.
The impact was immediate.
Lower-thermal density meant standard glass-reinforced, epoxy-laminated circuit boards could be used instead of more expensive aluminum-clad printed circuit boards. With the emitters packed tightly together, the LED light source more closely emulated a fluorescent tube, eliminating pixilation. This meant more efficient diffusers could be used, maximizing efficacy while still delivering a smooth, low-glare appearance. Higher overall efficacy also meant that the total power level fell so much that standard-formed sheet-metal housing was all that a heatsink required, eliminating the need for more expensive extruded or die-cast heatsinks.
The end result? The cost of LED products plummeted. They are approaching pricing parity with the outdated fluorescent products.
The next time you open up an LED product and see hundreds of mid-power emitters, you might be tempted to think, “Wow, that looks expensive.” On the contrary, all those emitters actually reduced the cost of the product.
This piece was originally published in the February 2016 issue of ei, the magazine of the electroindustry.