lighting products, pendant lights, and roadway luminaires. Although less constrained by “existing holes in the ceiling,” other LED products that might be categorized as retrofit luminaires include under-cabinet lights, showcase lights, pathway lights, and rope lighting products. These products take on similar forms to existing non-SSL luminaires.
Of this category of products, the most attention has been paid to SSL roadway lighting luminaires. While most of these luminaires produce luminous flux comparable to incumbent technologies, a few are significantly dimmer (National Lighting Product Information Program, 2010; DOE, 2012). Some of the advantages of LEDs, such as long life, high performance in cold environments, and robustness, make SSL very attractive for many roadway applications. As with replacement lamp products, however, the spatial distribution of light is very different from many SSL roadway luminaires than from other types of light sources. This is frequently a disadvantage, because consumers expect a replacement product to behave identically to the preceding technology. Some outdoor luminaires have significant glare, which is not desirable.
One advantage is that the LED luminaire has the opportunity to direct light more toward the task, thus reducing wasted light and helping to control light pollution.
Another application where retrofit luminaires with LED have done well is recessed cans. Websites including those of the ENERGY STAR® program, U.S. Department of Energy’s Lighting Facts, CALiPER, and Gateway programs are places where one can gather information regarding the performance of commercial LED lighting luminaires (Next Generation Luminaires, 2012; DOE, 2012). Figure 4.7 illustrates examples of 2011 performance data for downlight luminaires for commercial lighting applications. As seen, in 2011, the luminaire efficacies of ENERGY STAR®-rated LED downlights are in the range 35 to 85 lm/W. In comparison, CFL and halogen downlights are in the range of 10 to 30 lm/W.
Even though LED luminaires have greater luminous efficacy than traditional light source luminaires, LED luminaires can have greater lamp to lamp color variation, glare, and flicker and cannot be dimmed.
FINDING: While the majority of LED products in the marketplace have better luminous efficacy than traditional lighting technologies, for many of them, other quality factors, such as useful life, color appearance and rendering properties, beam distribution, flicker, and noise, may be inferior to traditional lighting products. Even though the optimistic view is that energy has been saved by using SSL technologies, if other factors such as system life, lamp-to-lamp color variation, glare, flicker, and dimming, do not meet user expectations, they could slow down market adoption of SSL technologies.