January 01, 2013
| by Steven Castle
Think light emitting diode (LED) lighting is cool? It’s super-efficient, it can be used to create colored lighting effects. They’re great for both in-home and commercial installations. But we may be seeing nothing yet.
Next on the horizon is LED lighting that uses Power over Ethernet (PoE). This means that the LED light fixtures can be powered not by an electrical powerline but by your basic Ethernet cable. The Category 5 or Cat 6 cable can send both power and data to LEDs. And that can save on wiring costs as well.
“As lighting becomes more and more LED, you’ve got a digital, electronic device,” says Lisa Isaacson of nuLEDs, an LED manufacturer in Vista, Calif., which is working on LED PoE solutions. “Being part of an Ethernet system makes it easy to measure it, monitor it and control it. Each LED [fixture] can be an end point on a network.”
Not only can each LED lamp be controlled and monitored separately, colored RGB LEDs can be controlled on the network to create effects. Or the lights can be dimmed with in-line photo sensors in subtle ways to complement ambient light and thereby save energy. Or occupancy sensors can turn off the lights when no one is in the space and light pathways at night.
Proximity sensing is also possible, so when someone enters a space with a smartphone, the lights can come on to preset levels, as has been discussed by Google’s Android @Home technology using LEDs from Lighting Sciences Group.
NuLEDs is looking to target commercial buildings initially, but the technology could be implemented in homes and large homes.
JouleX recently demonstrated its new JEM mobile device capabilities using NuLEDs fixtures controlled by Cisco’s EnergyWise energy managament system at Cisco Live in San Diego, June 10-14. You can see a video of it here.
With PoE+, 25.5 watts per port (or cable) can be sent over PoE, and Cisco’s Universal PoE (UPoE) technology ramps that up to 60 watts per port, so multiple LED fixtures can be powered by one port.
NuLEDs’ Isaacson says further advances in efficiency can be achieved with full DC-powered lighting, especially when powered by DC-based systems like solar photovoltaic arrays.
One of barriers in the LED lighting industry right now, she explains, is people trying to do replacement bulbs with Edison-based screw-in-lamps, necessitating an AC-to-DC conversion at each light, which sacrifices efficiency, as the converters do not convert 100 percent of the AC power and lose the rest as heat. This also adds to the heat generated by the LED lamp’s silicon chip in the back of the fixture.
A Carnegie Mellon University (CMU) report states that a direct current (DC) electrical power system is most economic way to power lights in buildings, especially in those using solar photovoltaics (PV). CMU found that in a 48,000-square-foot building, using LEDs powered by a central DC system instead of AC, could save of $24,000 per year. If the LEDs were powered with solar PV augmented with grid electricity, even bigger savings of $5,000 per year could be gained. However, the study also found that using DC to power fluorescent lights in the same-size building resulted in the same or slightly higher cost as AC. Such DC power could come to homes as well, though that may be some time away.
nuLEDs from VideoBuilders on Vimeo.
Steven Castle is Electronic House's managing editor. he has been writing about consumer electronics, homes and energy efficiency topics for two decades. He is also the co-founder of GreenTech Advocates