Guest post by Jim Brodrick, U.S. Department of Energy
Because they’re directional, reflector lamps are an important tool for both ambient and accent lighting, especially in residential and light commercial applications. One common type of reflector lamp is the PAR lamp, which is often used in demanding applications where color quality and visual appearance are important considerations – such as museum, retail, hospitality, and landscape lighting. Although the directionality of LEDs makes them well-suited for use in PAR lamps (see DOE fact sheet on LED directional lamps), the effectiveness and utility of conventional halogen PAR lamps present a challenge to SSL. LED PAR38 lamps are making significant strides in matching – and even surpassing – the performance of their halogen counterparts across many parameters, but there’s still considerable room for improvement. For example, none of the LED products currently on the market comes close to DOE’s targets for the recently reopened PAR38 category of the L Prize® competition.
DOE’s CALiPER program recently tested the photometric performance of 38 LED PAR38 lamps. The report, which was released last month, is available online. The results show substantial improvement over earlier CALiPER testing of similar products, and performance comparable to recent data from LED Lighting Facts and ENERGY STAR.
Many of the LED lamps tested could be effective replacements for conventional directional lamps in the right application. The tested LED products emitted between 388 and 1,363 lumens, covering the approximate range of 40W to 90W halogen versions. Efficacy ranged from 44 to 79 lm/W, with the exception of one low outlier (26 lm/W). Most of them had an efficacy between 50 and 60 lm/W, and the average was 56 lm/W – which compares favorably with other light source types commonly used in directional lamps (e.g., less than 25 lm/W for halogens) and should continue to rise.
The LED PAR38 lamps had luminous intensity distributions ranging from narrow (8° beam angle) to very wide (64° beam angle). Although the suitability of these distributions depends on the application, the range covers what’s available from halogen PAR38s. The availability of narrow distributions in the LED products is an important finding that illustrates that market’s response to the demands of specifiers.
Although there were a few exceptions (two products had a CCT above 5000 K, and three had a CRI of less than 80), most of the LED lamps had color quality attributes that were appropriate for replacing halogen PAR lamps in most applications. Some applications, such as museums, may require better color rendering, which may limit the number of available LED options.
Many of the manufacturer claims were accurate, although there was a tendency for the lamps to actually exhibit higher efficacies and draw less power than reported in the manufacturers’ literature. A number of products also emitted fewer than 90 percent of claimed lumens, and the measured beam angle for six products was outside the tolerance established by the American National Standards Institute.
All of the LED PAR38 lamps tested offered substantial energy savings compared to halogen PAR38 lamps. What’s more, the efficacy and color characteristics of the LED lamps are similar to or better than directional CFL and ceramic metal halide lamps, yet the LED lamps offer more variety and better operating characteristics, such as instant-on performance. Adding in other factors, such as dimmability and longer rated lifetime, makes LED PAR38 lamps strong contenders for replacing inefficient incandescent or halogen PAR38 lamps.
Although the results of the CALiPER study were encouraging, there’s room for LED PAR38 lamps to improve and gain a larger market share. Many of the products tested had more than one option for beam angle and color temperature, but products available in multiple lumen packages were less prevalent. Another current concern is cost; the LED products tested were, on average, several times more expensive than their halogen counterparts.
CALiPER plans to conduct additional testing on these same LED PAR38 lamps, to investigate performance attributes that aren’t captured by LM-79 testing. The results of this additional testing will be published in subsequent reports and complement the L Prize PAR38 competition.
