Smarter LED Lights

A new approach to LED lighting uses network cables, rather than conventional electrical wiring, to supply power to lights. Developed by a startup in Fremont, CA, the system also allows the cables to carry data from an array of sensors on the lights to a central control station. The system would cost about the same as a conventional lighting system, but because it can sense and control every light in a building, it could cut power consumption from lighting by 50 to 80 percent.

The new system offers a better way to control LEDs, which are relatively efficient and long-lasting compared to conventional lights, by taking advantage of the fact that they run on low-voltage direct current power. Current LED-based systems require transformers at each light to convert the higher-voltage alternating current in conventional wiring into lower-voltage direct current. The new system converts alternating current to low-voltage direct current at a central location, rather than at each light. This more efficient method cuts energy consumption by 10 to 20 percent, according to Jeremy Stieglitz, vice president of marketing for Redwood Systems, which will start selling its systems this summer.
The remaining energy savings come from using sensors and a central controller to reduce light use. The company has also developed a method for using those same power cables to carry data. Each LED can be fitted with inexpensive sensors that can be used to optimize light levels and ensure the lights are operating efficiently. Such sensors can also provide detailed information about temperature and where people are in the building--information that can be used to control heating and cooling systems. The sensing and controls, says Steiglitz, add very little cost to the new system because the network connections and power supply for the sensors are already in place.
Each light comes equipped with six sensors. Two are similar to what's used in some newer lighting systems--they detect motion and ambient light (used to turn off lights when there's enough daylight). But where conventional systems control all the lights for an entire room or open cubicle area, the new system allows for control at each light. So the system could, for example, compensate for lower daylight levels further from windows, or dim lights in a large space where no one is working. The new system also monitors task lighting with a third sensor, to ensure that desktops are receiving enough light (something individuals could set according to their preference).

The remaining three sensors can optimize the efficiency of LEDs and help control heating and cooling. A voltage and current sensor detects how much power each LED is using. A temperature sensor on the LED itself, along with one that measures ambient temperatures, tells the central controller if the light is operating at ideal temperatures.
The new system could lead to "huge cost savings," particularly for installing lighting for new buildings, and it could improve the consistency of lighting in a building, says Avraham Mor, a partner in the lighting design company Lightswitch, based in Chicago. But he says installers will have to be educated on the system, and it could be difficult to convince an entrenched lighting industry to switch to new technology.

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