Below is an article I wrote for TED Magazine, which was published in its September 2014 issue. Reprinted with permission.
Although LED directional lamps are steadily improving, halogen reflector lamps remain most popular for directional lighting applications and the gold standard to beat in terms of overall performance.
Available in a wide range of configurations, halogen offers a number of advantages. Besides a low initial cost, the lamp starts instantly, provides excellent beam control and is easily dimmable across the full range of output. Lumen maintenance ranges from 88 to 92 percent. A strong advantage is color, as the lamp emits light across the full color spectrum, with a high CRI of 100, high R9 value of 100 (resulting in excellent rendering of saturated reds), and warm-white color appearance. Frequent switching does not affect life. The lamp can be used outdoors, is resistant to thermal shock, and can operate in areas with high humidity. There are no disposal issues related to mercury and lead, no RF emissions, and no power factor issues.
However, halogen lamps are vulnerable to competition by upstart LED based on three relative disadvantages. First is relatively low efficacy, as halogen lamps operate at 18-24 lumens/W. In contrast, good LED lamps are available that operate for up to 85 percent less energy. Next is relatively short service life. Finally, halogen lamps emit more heat into the environment, which can be particularly disadvantageous in art and museum applications.
“Current and future prospects for halogen reflectors remain strong,” says Shilpi Biswas, Global Product Manager – Lamp Products for GE Lighting. “Halogen remains an initial acquisition cost advantage over current LED. Light quality is preferred over LED and CFL alternatives, especially with a CRI of 100. Currently, no LED challenges halogen on this. As acquisition costs of LED continue to fall, however, this will put pressure on halogen reflectors.”
Today’s offering of halogen reflector lamps is more efficient due to multiple rounds of energy efficiency standards implemented since 1992, with the most recent regulations effective in July 2012. The most-efficient lamps utilize an infrared-reflecting (IR) coating on the inside of the halogen capsule, which reflects waste heat back into the filament. This can be leveraged to increase efficiency, service life or both. The most-efficient halogen IR lamps are 30 percent more efficient than standard halogen lamps, while the longest-life lamps are rated up to 4,500 hours. The result is several tiers of lamps available from manufacturers, from basic to premium lines, that meet various end-user needs.
“If a lamp was on the market prior to the big regulation changes in July 2012, there is currently a replacement available today,” says Soares. “Contractors and end-users can still use halogen reflectors to refill sockets, as all of the phased-out versions have good replacements to choose from. Both PARs (PAR20/30/38) and soft-glass reflectors (R20/30/40) offer the same or nearly identical performance in life and lumens as their predecessors, but are made at a reduced wattage, typically 20-30 percent less than their predecessors.”
Currently, regulatory exemptions for <50W ER30/ER40, BR30/BR40; 65W BR30 and BR40/ER40; and <45W R20 lamps are expected to continue until at least December 31, 2014. DOE is currently reviewing new energy standards for halogen lamps and will be reviewing whether to continue these exemptions, some of which are popularly used in the residential market. “The rulemaking was announced in the second half of 2011, and the DOE’s intent is to complete it by the end of 2014, although dates can be slip backward,” says Biswas. “Rules are typically effective three years after being finalized, which means the next round of regulations affecting halogen PAR lamps will most likely occur at the end of 2017 or 2018.” In directional lighting, halogen remains the most popular light source, though LED is on the rise. In May 2013, the U.S. Department of Energy (DOE) estimated that of the 248 million lamps installed in this market, 59 percent were halogen, primarily PAR and MR16 with some R and BR lamps, while 25 percent were incandescent (R/BR), 11 percent were compact fluorescent (R/BR) and 4.6 percent were LED. (Ceramic metal halide was not included.) About 80 percent of reflector lamps are used in residential applications. “Halogen still has a strong customer base and will be viable for several years, until the price/benefit relationship for LEDs eventually exceeds halogen,” says Peter Soares, director of product marketing for Philips Lighting. “We’ve seen many end-users in the retail and hospitality applications switch to LED. However, many in those same applications continue to use halogen because they prefer the color or beam intensity of halogen, or because the cost/investment to switch is still prohibitive in their situation.” [caption id="attachment_9892" align="alignnone" width="529"] Available in a wide range of configurations, halogen offers a number of advantages such as low initial cost, instant starting and excellent beam control, dimming and color quality. Image courtesy of Philips Lighting.[/caption]
Cheryl Ford, marketing manager for OSRAM SYLVANIA, says there are now very good LED lamps with a CRI rating higher than 90 that closely match the color quality of halogen lamps, though they’re a little less efficient than 80+ CRI LED lamps. “For color-critical applications like high-end retail and museum lighting, 90+ CRI LED lamps should be specified to not only get the color quality desired but maximize on energy and maintenance savings over halogen options,” she says. “For conference rooms, corridors and general lighting with downlights, LED PAR lamps should be acceptable.”
Ford adds that another factor is dimming. Dimmability of LED lamps is improving, but none provide dimming to 0 percent like halogen. “Most LED lamps will drop out at 10 percent of power,” she explains. “One hundred to 5 percent dimming is probably the best out there at this time. End-users also need to make sure they check dimming compatibility lists that can be found on most manufacturers’ websites. For hospitality and theater lighting, dimming to at least 1 percent of power is typically desired, so halogen would be the best choice. By using halogen lamps, color and brightness will be more consistent lamp to lamp at low dimming levels and as lights are being brought up.”
Soares adds: “There is a combination of elements to consider, including the application, the fixture, how people use the space, economics, etc. If the end-user can see a reasonable return on investment, then switching to LED today makes sense. However, if a renovation is planned two years from now, they might consider sticking with the current technology for another one to three relamping cycles.”