The LED prototype downlight designed by the LRC for passenger elevators.
The low profile of the fixture (1.5 inches tall) allows it to be used in small spaces, or can allow manufacturers to reduce the space necessary to fit lighting.
The prototype LED downlights installed in an elevator on the Rensselaer campus. At the same interior light level, the fixtures showed 45% energy savings over the incandescent downlights they replaced.
Low-Profile LED Fixtures for Elevators (2005)
LEDs are an ideal solution for applications requiring small or low-profile light fixtures. The LED’s smaller size, long life, low energy consumption, and durability make it a great choice when space is at a premium.
During a two-year project, the LRC developed and evaluated a low-profile LED downlight to replace a less efficient incandescent luminaire in an elevator application.
PROTOTYPE DEVELOPMENT AND FIELD STUDY
The objectives of this project were to:
- Develop prototype LED luminaires that will use up to 20 percent less energy than incandescent and halogen lighting technologies.
- Optimize the efficiency, size, and optical performance of LED luminaires to meet lighting design needs.
- Improve the cost-effectiveness of current LED luminaire technology.
- Develop LED luminaires that will be easily controllable, dimmable, and will quickly respond to needs for peak electric demand reduction.
The prototype downlights consisted of six high-flux white LEDs in a custom reflector and heat sink package of less than two inches high. The design efficiently balanced the required light output and distribution, visual comfort, and thermal management within a small and attractive package. The LRC used optical modeling software to optimize the efficiency of the reflector. LRC researchers also designed the heat sink for thermal management and the aluminum-core printed circuit board to house the LEDs and provide electrical connections
For the field study, the LRC selected and modified an elevator on the Rensselaer Polytechnic Institute campus in Troy, N.Y.. LRC researchers modified the existing elevator ceiling panel, removing the original incandescent downlights and replacing them with six prototype fixtures. The downlights were recessed into the ceiling and required less than two inches of space above the ceiling panel.
LRC researchers measured the LED fixtures' performance, including light output and power consumption, and compared them with the existing incandescent fixtures inside the elevator. The LRC also asked volunteers to ride the elevator and rate the existing and new elevator lighting.
The six downlights required 165 watts of electricity (including a complementary LED cove system) compared to 300 watts for the 50-watt R20 systems they replaced. At the system efficacy of the LEDs used, an energy savings of 45 percent was realized over the actual incandescent system (~5.5 lm/W).
The LED luminaires provided similar light distribution and illuminance levels inside the elevator cabin with better comfort and attractiveness, according to passengers. The survey also showed that better color rendering and a color temperature lower than 6500 K would be desirable.
LED downlight fixtures in elevators can be expected to save more than just lighting energy. LED fixtures are expected to last 40,000 hours, or more than four years being on all day, every day. That is compared with traditional incandescent fixtures in elevators, which operate between 1,500 and 2,500 hours. LED fixtures also have the ability to work with on-demand dimming and motion-sensing lighting controls for added savings. Their rugged design means they are resistant to elevator cabin vibration, potentially reducing maintenance needs. Overall, LEDs can provide cost savings for replacement and maintenance.
LED downlight fixtures could have an even greater impact on the elevator industry in terms of elevator design. The low-profile design of the LED fixture means that elevator manufacturers can shorten the height of the elevator cabin by as much as four to six inches, the current clearance needed for traditional incandescent and fluorescent fixtures. In turn, this means less materials are needed to build the cabin, reducing the cabin’s total weight. Less weight translates to smaller motor and braking systems—an added energy savings.
LED products also can open the door to new interior designs for elevators, such as panels of lighting on the walls, color-changing effects, and other kinds of lighted aesthetic or informational displays.
- LED module efficacy: 18 lm/W at 15.4 W
- Reflector efficiency: 75 percent
- Luminaire light output: 210 lumens
- Luminaire power (including driver): 21 W
- Luminaire efficacy: 10 lm/W (210 lm at 21 W)
- Color rendering index of 65 at 6500 K
- 40-degree beam angle
PROJECT REPORTS & PUBLICATIONS
PROJECT-RELATED NEWS AND LINKS
California Energy Commission PIER Program
Architectural Energy Corporation
Advanced Transformer Co.
Otis Elevator Co.
Rensselaer Polytechnic Institute