I wrote this article for the March issue of tED Magazine. Reprinted with permission.
The year 2014 represented a major milestone in adoption of LED technology in terms of demand and product design.
With energy savings as high as 30-40 percent (not including additional control impacts), long rated life (with the promise of little or no spot relamping), and ongoing cost reduction, LED continues to gain in popularity. It is attractive not only in new construction—particularly in building designs regulated by more stringent energy codes—but also relighting projects offering attractive economics.
In November 2014, a survey was distributed to 1,679 lighting manufacturers subscribing to the author’s LightNOW newsletter, with a 4.7 percent response rate. Respondents at companies manufacturing indoor luminaires with a mix of conventional and LED sources were isolated. The average respondent in this group reported that 45 percent of their U.S. indoor luminaire unit sales as of that time in 2014 were LED-based.
Today, LED luminaires are competing for virtually every interior application. “At this point, virtually every project now quotes an LED option, especially for environments where dimming is required, and LED solutions are approaching cost parity with traditional sources,” says Kraig Kasler, Vice President and General Manager, Indoor, Eaton’s Cooper Lighting business. “In the commercial space, we are seeing a lot of customers purchase LED troffers, strips and downlights. In the industrial space, given the maintenance advantages, we are seeing a significant transition towards LED high-bays. Now that LED fixtures have been developed that cover the basics of good lighting design—general, task, accent and wallwashing—most indoor applications are covered.”
“Hubbell Lighting’s overall adoption of LED luminaires is quickly approaching 50 percent,” says Chris Bailey, LC, LEED AP BD+C, DDI, MIES, Director, Lighting Solutions Center, Hubbell Lighting, Inc. “While this tremendous shift is somewhat influenced by the moderate recovery in the new construction market, in general, the installed base of legacy technology in the market will remain the most significant market opportunity in the near future.”
As LED technology matures, the overall product offering will continue to stratify in a way consistent with traditional lighting. “Trends in indoor LED luminaire design may accelerate the segmentation of the LED-based luminaire market into a ‘white goods’ segment and a ‘tailored lighting’ segment,” says Terry Clark, Chairman, Finelite, Inc., who estimates that more than 70 percent of new construction and major remodeling projects incorporate LED products. “The white goods segment will deliver more performance in lumens per watt at lower cost and require successful companies to be volume leaders. The tailored segment will need to reduce lead times to meet more project requirements and provide cost-effective ways to make the specifier’s vision a reality.”
Bailey agrees, adding, “Some degree of stratification has already occurred in the lighting marketplace. This is consistent with the conventional lighting marketplace, where products can be categorized as commodity, specification or somewhere in between. In other words, LEDs are now equally relevant for almost any application—not just the specification market.”
Image courtesy of Columbia Lighting.
New form factors and optics
Conventional luminaires were designed around the physical dimensions of those light sources. Early generations of LED luminaires attempted to incorporate early LEDs into essentially the same design. Many new LED luminaires are taking advantage of the LED as a very small light emitter to reduce luminaire size and create new form factors.
“The fundamental rule of optics is the larger the emitter, the larger the optic,” says Tim O’Brien, Commercial Office Practice Director, Acuity Brands Lighting. “The beautiful thing about LEDs is that the emission is very small. It gives the designer such flexibility.”
As efficiency and thermal performance in LED packages continue to improve, fewer LEDs may be needed to satisfy light levels and optical distributions. This allows even greater flexibility in optical and mechanical design. An example is new flat surface-mounted LED downlights that mount directly to the junction box, protrude an inch or less from the ceiling, and provide similar light output and appearance as recessed downlighting, ideal for applications where ceiling clearance can be an issue.
“This has been one of the truly exciting aspects of the transition to LED,” says Kasler. “Lower wattage will lead to smaller fixtures, which will continue to allow for smaller apertures with higher lumen potential. With the new light sources, we have been able to design to new form factors—smaller, lighter, thinner, edge-lighting—and this trend will only increase, especially as thermals become less and less of an issue over time.”
Clark points out that miniaturization facilitates the design of shapes that include complex angles and custom lengths, allowing designers greater flexibility and giving the ability to solve a wider range of design challenges.
“LED luminaires have the unique ability to transcend traditional luminaire design and break new ground,” Bailey says. “LEDs can be incorporated directly into the fabric of a luminaire concept. Flexible and translucent circuit board technologies provide the ability to move luminaire designs from routine, predictable and rigid forms into an era of freeform design without rules of scale, size and structure.”
Clark says the only thing holding back the potential of this capability is the traditional construction process. “New form factors are coming,” he notes. “However, it is important to remember that many projects require that an ‘equal’ luminaire be available from more than one lighting manufacturer. To the extent this continues, most unique shapes will likely remain decorative luminaires that service market niches.”
The directional emission of LEDs, meanwhile, has also sparked the development of optics that go beyond traditional reflectors designed around omnidirectional traditional sources. The most common is TIR optics, typically constructed of injection-molded acrylic and for which optical efficiencies greater than 90 percent are possible. Some luminaires combine TIR optics with reflector-based optics to optimize both visibility and visual comfort.
“Not only are TIR optical systems efficient at transmitting light into the space, they uniquely enable the precise placement of light within a space,” Bailey says.
Other developments have been made in edge lighting, light guides and micro or imprinted optics, in which complex optical structures are created on thin optical sheets or films that facilitate transmission, diffusion and optical control.
“Refractor optics potentially offer the ability to improve optical efficiencies substantially, while touching more of the light, which further translates to getting more of the photons to where they need to be in the application,” Kasler says.
Smaller LED packages facilitate the design of shapes that include complex angles and custom lengths, allowing designers greater flexibility and giving the ability to solve a wider range of design challenges. Image courtesy of Finelite.
Controllability
The latest generation of energy codes require highly efficient, bilevel lighting, favoring LED that is not only low in power but also often offered with 0-10V dimming control standard. One of the most exciting trends in indoor luminaire design is intelligent (digital) control, allowing a wide range of capabilities:
• Luminaires can be individually zoned and/or zoned in groups, later rezoned, and calibrated using software.
• Luminaires can be programmed to produce constant light output over the life of the luminaire, generating additional energy savings while potentially extending product service life.
• Luminaires can be programmed with custom wattage and light output settings to satisfy precise design requirements.
• The white light emission of the luminaire can be precisely tuned to satisfy the application needs after installation, and can be configured to change dynamically based on time, user preference or other inputs.
Sensors and controllers may be integrated within the luminaire and may communicate using dedicated control wiring or wirelessly using a radio frequency.
Final word
“Similar to consumer electronics from five years ago, we are just scratching the surface of the value that we can provide,” O’Brien says. “We will see better integration of building systems, the ability to personalize, new form factors. Everything will change in the next five years.”
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