(March 2010) Share |
Redwood Systems brings network-powered approach to LED office
lighting08 Mar 2010A shared power source and luminaire connectivity
and control hold the promise of energy savings in new or remodeled
office environments. Redwood Systems based in Fremont, CA emerged from
stealth mode with a new network-centric approach to LED lighting in
commercial environments that's driven by a team out of the computer
networking industry. The company plans to deliver energy savings by
consolidating the LED power source, distributing DC power and control
signals to fixtures, and relying on efficient LED technology.
Although product specifics won't come until Lightfair in Las Vegas
this May, Redwood is conducting ongoing field trials of its
technology. VP of Marketing Jeremy Stieglitz claims the
technology-heavy approach can deliver a return on investment in two
years for commercial spaces. The company claims its technology will
deliver more than 90% of the input power to the LED.
Lighting is a huge component of the energy bill for most commercial
enterprises, and is the reason for the recent surge of interest in LED
lighting that uses less energy than alternatives such as fluorescent.
Redwood wants to extend the savings by remotely controlling each
light, ensuring that lights are only on when required.
Referring to businesses, Stieglitz states, "Lighting is 20% to 40% of
their energy load and they have no visibility into it." He claims that
businesses want to cut energy cost and want better instrumentation in
the lighting plant.
Redwood Systems LED light control engine Redwood's technology will
provide both the ability to control the lights and to monitor energy
usage at each light and other operating characteristics such as
temperature. Stieglitz stated, "We will offer richer sensor
distribution and more control at each light."
The control aspect includes dimming lights when workers leave an area
and tuning lights to a task. The system could also optimize energy use
based on utility rates and pricing programs. And the instrumentation
capability allows management of lumen depreciation and ensures the
system doesn't over-drive the lights.
The Redwood scheme will only be applicable in new construction or
major remodels because it relies on a new way to distribute power to
the lights. The company will offer centralized light driver systems
that distribute DC power and a network link to each light.
Given the founding team's heritage in the network space, the system
functions similarly to a computer network switch in a wiring closet.
Installations will even link the central systems to lights via network
cables in some cases.
A single pair of wires will carry both the constant-current DC power
needed to power a light and a proprietary power-line communication
network. For cable runs of 100 to 200 ft, the Category 5/6 cable used
in networks can deliver the required 350 mA of current at 60VDC –
meaning the system is classified as a low-voltage system from a
regulatory perspective. For longer runs to 100m, the system will relay
on moderately more expensive 18-guage wiring.
Centralizing the power supply offers several potential angles towards
system cost savings and ROI. A single PFC (power factor correction)
front-end stage supplies a DC voltage to each light channel where
dedicated DC/DC converters drive the lights. Stieglitz claims the
centralized PFC stage offers an 8:1 advantage relative to having a PFC
stage at each light.
Down the road, Stieglitz claims the cost comparison tilts more in
Redwood's favor. He sees the IC driver manufacturers developing
multi-channel DC/DC converters that increase the level of integration
in the system. Moreover green technologies such as solar and fuel
cells produce a DC output that could directly drive the system,
eliminating the inefficiency in the DC/AC inverter and subsequent
conversion back to DC at the legacy LED luminaire.
The centralized approach also offers a system cost advantage when it
comes to control. Stieglitz points out that a single FPGA IC can
implement 64 dimming curves each with 65,000 steps – one for each of
the 64 channels the initial system will support. Stieglitz claims that
the system offers "best-in-class dimming" at what is essentially a 20%
to 30% cost saving at the individual fixture level.
The challenge for Redwood will be the complete transition to a new
power distribution scheme. Surely some building engineers would prefer
a move to the savings afforded by LEDs while maintaining the legacy AC
power-distribution scheme.
Stieglitz states, "You can't be disruptive without creating pot
holes." But he believes the energy savings afforded by the centralized
DC approach will win out in new construction or remodels. He stated,
"I've seen a willingness to take on more change and more risk than I
ever would have expected."
LED and lighting manufacturer Cree lends credence to the Redwood
approach. "Redwood Systems has the potential for a new and better way
to power and control LED lighting that could add significant
intelligence to lighting systems and accelerate customer ROI through
energy savings and reduced installation costs," said Gary Trott,
vice president of market development of Cree."
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