Republication of Postings from the U.S. Department of Energy (DOE) Solid-State Lighting Program

by Jim Brodrick, SSL Program Manager, U.S. Department of Energy

At LIGHTFAIR® International, held a few weeks ago in the Windy City, the U.S. Department of Energy’s (DOE’s) Solid-State Lighting (SSL) team played to standing room only crowds in our award-winning booth, where we offered educational sessions about DOE studies, resources, and tools – such as connected lighting test bed investigations, color rendition research, and Next Generation Lighting Systems installations. But when we weren’t “on stage,” we took the opportunity to walk the show floor, which led to some eye-opening observations.

One of the most notable observations was that manufacturers are clearly focused on product differentiation, and efficiency can be a key factor in that. Many partner with DOE to conduct research that continually raises the efficiency of their products. They’re also focused on exploiting all of the other things that SSL can do. For example, there was definitely an increased emphasis on spectral tuning, compared to what we’ve seen at past LIGHTFAIRS. Many of this year’s booths exhibited LED lighting products that could produce a whole range of colors – even extending to ultraviolet (UV) and infrared – to affect such things as circadian rhythm, productivity, plant growth, and esthetics. Some products we saw could even mimic the progression of daylight throughout the course of a day.

Other levels of control were increasingly apparent as well. In addition to SSL products that could vary the intensity of the light emitted, there were quite a few that featured beam control, with custom secondary optics or dynamic changing beam patterns. One especially interesting technology, which has been incorporated by many luminaire manufacturers, utilizes an LCD flat lens to shape the beam, and looks like it could be a major step for solid-state lighting. The way it works is that the LCD is subjected to a shaped electric field, which orients the LCD crystals in various directions, causing different refractive indexes that allow users to change the luminaire’s beam angle dynamically, depending on the electric field applied.

It was clear from walking the LIGHTFAIR show floor that dim-to-warm is an LED luminaire feature that’s continuing to grow in popularity. And more manufacturers are offering products that dim down to 0.1% output. Zero-10V dimming controls are refusing to die out, with digital addressable lighting interface (DALI) and DMX protocols still taking a back seat because the simplicity and low cost of 0-10V outweigh the drawbacks of voltage-drop issues and confusion between linear and logarithmic dimming curves. Cost and complexity still pose barriers for the other two protocols.

It’s also clear that manufacturers are emphasizing visual comfort through better diffusion and optics, especially in the pedestrian-scale outdoor lighting category, as we saw fewer bare-LED products than we’ve seen at LIGHTFAIR in the past. And many companies were displaying “canless” LED recessed downlights, which are held in place by clips. We also saw a fair number of UVA and UVC LEDs – which, when integrated into luminaires, could increase the value proposition in settings that require disinfection, such as hospital rooms.

On the organic LED (OLED) front, we saw a greater variety of panel offerings – squares, rectangles, circles, and curved panels – and with efficacies of 85 lumens/watt (lm/W), manufacturers are shifting their focus to reducing cost, which remains OLED lighting’s biggest barrier.

It was heartening to see that a number of manufacturers are using IES TM-30-15 metrics – whose development was supported by DOE – to describe the light quality emitted by their products, reflecting the slow but steady progress that, with the help of DOE’s educational efforts, is being made in this area.

And once again, everywhere we looked at LIGHTFAIR, there was connected lighting – which, as the DOE report Energy Savings Forecast of Solid-State Lighting in General Illumination Applications shows, is critical to realizing SSL’s energy-saving potential. But unlike last year, it didn’t feel like connected lighting was the main theme of every LIGHTFAIR booth, because of the increased focus on SSL’s other capabilities and options. Many of those capabilities and options have been enabled, at least in part, by the advances that have been made in efficacy.

But those advances still leave considerable room for improvement. SSL technology on the whole is at a level of maturity that’s comparable to the way cell phones were back in the 1990s. DOE’s role is to conduct early stage research and development that will help SSL evolve to achieve its full potential to revolutionize lighting services and slash energy use.

Craig DiLouie

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