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LD+A The Magazine of the Illuminating Engineering Society of North America

LED Testing & Application  

Modular LED Tiles Show Promise for Offices, Study Finds

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 speaks to LED's potential as a flexible lighting solution in office environments.

The installation at the offices of Paramount Pictures features 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. The demonstration was funded by the California Energy Commission.

The modular approach 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 (e.g., trapped heat) and the problem of quickly obsolete products.

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. 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.

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 into the mix.

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.

Users of the conference room greatly approved of the new lighting, with 83 percent stating they thought it 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. Photometric measurements taken before and after showed that with the new system, more light (on an average 45 percent) was directed toward the horizontal plane of the table and less light (on an average 25 percent) toward the walls, all while using approximately 61 percent less power than the previous system.

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 percent. 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 percent.

July 2013



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