In a Hollywood conference room, researchers from the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute and product engineers from OSRAM SYLVANIA capped off eight years of research and concept development with a field demonstration that takes LED lighting to the next level.
The first-of-its-type demonstration, installed at the offices of Paramount Pictures, features flexible, modular LED-lighted tiles on the ceiling and walls that can be moved to any location on a low voltage, DC-powered grid with wireless controls. Funded by a building energy research grant from the California Energy Commission, the project showcases a sustainable lighting system that can adapt to changing technology and space needs, as well as energy savings without sacrificing lighting quality.
Working With a Technology in Flux
One big challenge facing users of interior LED lighting is the rapid pace at which LED lighting products become obsolete. Every year, new products come to market with more lumens, better efficacy and color, and a lower price. Given the fixed nature of traditional lighting practice, in which luminaires are permanently installed and any movement or replacement requires the expense of electrical and construction repairs, it is understandable why a wait-and-see mentality has taken hold.
At the same time, LED lighting is now at a crossroads where it can either take the path of traditional lighting—that is, adopt the same form and design of luminaires and replacement lamps—or create a completely new archetype where the benefits and intrinsic qualities of LEDs can be highlighted. In 2004, the LRC decided to explore concepts beyond the traditional boundaries and began developing an interior infrastructure that could power LED lighting and other electronic devices.
In its approach, the LRC combined two concepts: One was to create an adaptable lighting solution that would allow users to change lighting by allowing them to move luminaires as easily as it is to move furniture and artwork. The other was to create a novel concept where LED lighting's benefits would be realized—specifically, energy savings and "tunability" to meet users' individual lighting needs and preferences—and its drawbacks mitigated, including design issues that can trap heat and the problem of quickly obsolete products.
From Lab to Field
Given the necessary power conversion for LEDs to operate, the LRC conducted laboratory investigations of a DC infrastructure grid design in which AC power would be converted and distributed to the light sources. Many electronics require this type of power conversion, such as flat screen televisions, wireless speakers, computers, and sensors. One way to make power conversion of multiple low voltage and low wattage devices more efficient is to have it performed by a converter in a central location, which then distributes DC power to all devices through a building's infrastructure.
In 2005, the LRC built a laboratory model of an executive office with seed funding from the ASSIST program (Alliance for Solid-State Illumination Systems and Technologies). In the LRC's design, the grid consisted of low voltage (24 V) power and controls together with a quick connect-disconnect mechanical connector that allowed LED-lighted tiles to "snap" in and out, enabling the movement of tiles to any location on the grid.
While the laboratory model showed the possibilities for such a concept, to determine whether the concept could actually work and provide benefits above and beyond the traditional lighting infrastructure would require a real-world demonstration. The field demonstration required further work to develop methods for electrical connection and joining the tiles, aesthetic refinements, and choosing a form factor that could accommodate existing spaces for retrofit projects.
The field demonstration project team set out to find commercially available building materials that could be customized to create the low voltage, DC-powered infrastructure and LED-lighted tiles. For the walls, a commercial shelf lighting product with an integral power feed was customized to accept 2 ft. by 2 ft. metal tiles with power-conducting mounting hooks to energize the luminaires. The tiles with built-in LED luminaires had wireless controls. For the ceiling, a dropped ceiling product with an electrified grid accommodated the same 2 ft. by 2 ft. metal tiles. Because the system is modular, it can be adapted to typical commercial room geometries and diverse architectural designs, such as wall and ceiling curves. In addition to the LED-lighted tiles, non-lighted acoustic tiles helped fill in the edges around the room's periphery. At the field demonstration site, acoustic tiles were cut onsite to accommodate sprinkler heads.
To manage the system's heat and ensure maximum life and lumen maintenance, LEDs were mounted to metal plates and housings to extract heat. Prior to the field installation, the prototype tiles were tested in the lab for their thermal management performance to ensure that the tiles stayed within the manufacturer-recommended temperature limits for the LEDs.
Site Installation and Evaluation
Prior to the grid and tile installation, the existing conference room lighting, consisting of fluorescent pendant uplights and incandescent downlights, was evaluated. Performance and user surveys were conducted for comparison with the newly installed LED lighting. One objective of the new lighting design was to meet the task needs of conference room users (e.g., lighting for meetings, audio/visual presentations, etc.), which was determined to be possible with the new modular system, although the distribution of light would be different than before. During the installation, the new dropped ceiling was installed, providing the DC power distribution, and wall mounting grids and brackets were hung for the wall-mounted tiles. Self-luminous frames to backlight movie posters were also introduced.
Feedback received from the installation crew indicated that the installation went smoothly, and they offered helpful feedback for improvements to the system. Another major objective of the project was to demonstrate easy movement and reconfiguration of the lighted tiles, which was achieved in the laboratory version of the system and with demonstration's wall tiles. These tiles were easily moved in less than a minute. However, in the case of the ceiling lights, California's seismic stabilization requirements became an issue. While the original system design included earthquake wires, local code inspectors required the demonstration ceiling tiles to be permanently fastened, taking away the ability to move the ceiling tiles easily. Future system development will need to address ceiling tile movement in collaboration with seismic requirements.
Because several different lighting effects can be mounted in a single tile and controlled separately, the infrastructure can provide different lighting effects. For the demonstration, six types of lighted tiles were designed to provide nine layers of lighting, including downlighting, diffuse "cloud" lighting, wall-wash task lighting, wall sconce uplighting, and colored halo lighting in red, green, and blue. Occupancy sensors and dimmers were incorporated into the system, and dimmer switches were programmed to operate groups of lights cohesively. Each lighting layer was controlled separately and remained controlled by the same dimmer switch when moved to another location on the grid.
When comparing the lighting quality before versus after, users of the conference room greatly approved of the new lighting, with 83 percent stating they thought the new lighting was better than the lighting available in other conference rooms. In surveys taken before the installation, only 34 percent had that impression about the existing lighting. The overall effect and ability to take advantage of different lighting schemes and colors were well received by the conference room's users. Certain issues, such as complexity of controls, were ones highlighted by survey respondents as needing improvement. An upgrade to a scene controller with labeled lighting presets, especially one with a touch screen, would create a more user-friendly experience.
Light Level and Energy Comparison
Photometric measurements taken before and after showed that with the new lighting system, more light (on an average 45%) was directed toward the horizontal plane of the table and less light (on an average 25%) toward the walls. Surveys showed that users felt the lighting in the conference room was much better than before. The most notable aspect of the change was that the improved lighting with the new LED system was achieved at a much lower power demand, on average 61% lower compared with the previous lighting system, consisting of linear fluorescent and incandescent lamps.
One significant lesson learned from this field demonstration was the amount of energy demanded even when the lights were turned off. A major draw of energy came from the sensors built into the luminaires and the quiescent power demanded by the power supply. As a result, the estimated annual energy savings was reduced to 14%. Therefore, in future developments, power supplies with reduced or no quiescent power will need to be incorporated to maximize energy savings. Alternatively, the addition of a time clock to turn off the standby power during evenings and weekends would increase annual energy savings to as much as 60%.
Future Opportunities
Energy savings combined with high quality lighting and interchangeable, easily upgradable tiles present a plug-and-play system that is fully flexible and sustainable for many types of commercial, and possibly residential, uses. Future marketing of the LED grid infrastructure system will seek to capitalize on opportunities for both energy savings and customization of the system. The energy savings demonstrated with today's technology (at 85 lm/W in 2012) is expected to more than double by the year 2020, when LEDs are expected to reach 200 lm/W efficacy. Because the lighted tiles are easily moved and replaced, new tiles can be purchased as more efficient models come to market. Custom looks also are achievable and expected to be a strong selling point. With a modular system such as this, there is an opportunity to develop tiles with a variety of looks and finishes to complement any interior design.
