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New
Technologies Set the Stage for Dramatic Expansion of Wireless
Control
By
Craig DiLouie, Lighting Controls Association
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 Wireless
control is one of the most exciting frontiers in lighting
control and energy management, offering significant potential
benefits for residential and nonresidential lighting systems,
large and small buildings, and both existing buildings and new
construction. New technologies are now being commercialized that
will redefine wireless control by dramatically expanding its
utility.
All
lighting systems incorporate control functionality that enables
on/off switching and/or dimming. Automating this functionality
is proven to significantly reduce energy costs and provide other
benefits. Many types of lighting automation systems consist of a
hierarchy of connected control devices in which control signals
are sent (either one-way or both ways) using low-voltage
communications wires. This wiring adds costs to the system.
In a
wireless control network, control devices communicate without
the need for dedicated communications wiring. Control signals
are communicated using radio-frequency (RF) waves or
along existing line-voltage power wiring (powerline carrier
or PLC). While a range of benefits is possible depending on
the approach, all wireless control systems can reduce the
installed costs of lighting automation. In some cases, RF
wireless is more cost-effective than PLC, and vice versa,
depending on the application. The best choice of technology for
a given project depends on a number of factors, including
capabilities, cost and limitations.
One
development of particular interest in the area of RF wireless
control is the development of new protocols that open the door
to increased application of RF wireless control strategies in
residential and, coming soon, nonresidential applications.
Manufacturers say that with new technologies now available, wide
adoption of RF wireless controls in commercial applications will
occur within five years.
In these
environments, wireless control will enable a lower cost of
implementation of lighting automation strategies, greater
flexibility, decentralized sensing and control, conditioning
monitoring, and theoretically, a platform for integration
between lighting and other building systems such as heating,
ventilation and air-conditioning (HVAC), security and other
systems.
In this
special report from the Lighting Controls Association, we will
discuss how RF wireless control works, how to evaluate available
technologies, and emerging technologies that may revolutionize
wireless control in both residential and commercial
applications. PLC control, a viable alternative, will be the
subject of a future report, as there are exciting advancements
in this area of wireless control as well.
RF wireless control
In an RF wireless control network, control signals are
communicated using radio waves at designated frequencies. When
AC current with certain characteristics is input to an antenna,
an electromagnetic field is generated that is suitable for
wireless communication with another device that has a suitable
receiver. Common household examples include TV remotes and
garage-door openers.
RF
wireless control has been commercialized for years for both
commercial and residential applications but development has
increased dramatically in the last five years in tandem with the
rapid acceptance of wireless networks for Internet access,
according to William Sandoval, Business Development Manager –
Digital Systems for Philips Lighting Electronics and the Advance
division.
“Cell
phones are a perfect example of where wireless technology is
likely headed,” he says, adding that lighting control is
increasingly benefiting from technological advancements in the
field.
“The
prevalence of such current ‘standards’ as cordless phones, cell
phones and PCs in our society reflects the fact that we live in
an increasingly wireless world, and this trend is only expected
to escalate,” says Stuart Berjansky, Senior Product Manager,
Dimming for Advance. “Wireless control can transform traditional
lighting into a wireless lighting communication and control
infrastructure. Easy to install and simple to use, the benefits
of this technology impact every aspect of building design,
operation and ownership. Wireless control will be ideal for
facilities that want to elevate their degree of intelligence,
performance, flexibility and sustainability.”
Evaluation
A number of RF wireless control options are available,
each offering its own level of suitability for a given
application. When evaluating a wireless control strategy, the
below relevant questions should be considered. These questions
will form the basis for examining popular wireless control
strategies.
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What will be the topology, or layout, for the network of
devices?
-
What is the communication range for each node, or device, in
the network?
- How
much power does the system require?
-
What is the bandwidth and speed that is possible for
transmission of data?
- Is
there a protocol, or common language, that enables multiple
vendors’ products to be interoperable in the network?
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What is the cost of the system?
Each of
these points of evaluation in turn can be related to the
protocol used, as the protocol affects the design of control
devices.
Topology
When designing a local area network (LAN), the designer
must consider its topology, or a schematic representation of the
layout of the nodes (devices) and connections between the nodes
indicating communication pathways for the exchange of data. The
right topology to a large extent depends on the location of
these nodes, with the assumption that they will be connected
using cabling or with some limit on the range of wireless RF
communication.
In a
star network, all devices are directly connected to a central
computer. In a ring network, devices are connected in a
closed-loop configuration. In a bus network, each device is
connected to a main cable or bus. In a mesh network, each device
is connected to all the others (or, as in the case of a partial
mesh network, some of the others—those devices with which they
typically exchange data).
One
advantage of a mesh network is increased reliability due to
redundancy. If one node fails, the rest will continue to
communicate directly (full mesh) or through intermediate nodes
(partial mesh). Mesh networks are ideally suited for
applications where devices are scattered. Because cabling is not
required, it is highly suitable for wireless control. In
addition, each device can communicate independently with every
other device, which enables condition monitoring and
decentralized intelligence.
Bandwidth
Bandwidth refers to the difference in Hertz between the
highest and lowest frequencies of a communication signal. In
computer networks, it is often called the data transfer rate, or
amount of data that can be transmitted between two points in a
given time period, usually a second.
Protocols & technology
Control devices from different manufacturers are
interoperable in the same network only if they can communicate.
To enable this communication, a protocol is needed which
provides a common language for control devices. Specifiers
should be aware that there are a number of competing protocols
which are distinguishable in their topology, maximum number of
nodes, range, bandwidth and power consumption. Tradeoffs occur
in some characteristics when maximizing others. The resulting
blend of characteristics makes the protocol competitive for
various applications. Protocols may be proprietary, meaning they
were developed by a manufacturer for its own products—and in
some cases for allied manufacturers adopting its protocol—or
open-source, meaning no single manufacturer owns it and it is
intended for use by the entire industry.
Bluetooth and WiFi, two of the first open-source wireless
protocols using a star topology, are ideally suited for
computers and personal devices but have disadvantages for
control of lighting and other building automation systems.
One of
the most significant newer technological developments in
wireless control is low-powered mesh networks populated by
devices that use protocols accepted by a significant portion of
the industry, according to Mark Walters, Director of Residential
Systems for Leviton Manufacturing Inc.
“Mesh
networking protocols promise to provide new levels of system
performance,” he says. “True two-way reliability combined with
interoperability between multi-vendor platforms provides
integrators and end-users with control options that previously
were only available to the very high-end market.”
He adds
that the capabilities and price accessibility of the newer mesh
network technologies will drive demand for wireless controls
into the near future. Two mesh network protocols to watch are
Z-Wave and ZigBee.
The Z-Wave Protocol
Z-Wave began as a proprietary protocol but has gained
considerable traction in the residential market, making it de
facto an open standard. Z-Wave was developed by Zensys, a home
controls manufacturer, and is shared with partnering
manufacturers through the Z-Wave Alliance, which presently
includes more than 125 partners, including manufacturers such as
Leviton and Motorola. Z-Wave products are commercially available
and have been shipping since 2003. Leviton is planning a line of
Z-Wave-based residential controls in the fall of 2005.
According to Walters, Z-Wave offers the advantages of low power
consumption (enabling battery-operated control devices); good
node count, range and bandwidth for command and control for
residential applications; reliability; an attractive price
point; and a strong vendor alliance group to help guide the
technology.
“This
currently is the most widely adopted wireless solution for
residential control,” he says, although he adds that Z-Wave has
utility for small-scale commercial applications as well.
Raoul
Wijgergangs, Vice President of Business Development for Zensys,
confirms that more than 90 percent of products designed to
operate using the Z-Wave protocol are for residential
applications—lighting and theoretically, any other control
device.
“With
standardization, thermostats and lighting systems can talk to
access control and security systems and everything works in
concert,” he says.
RF
wireless control has proliferated largely in residential
applications to date, with significant promise for
nonresidential applications. Wireless control offers a method to
provide the homeowner with the benefits of lighting automation,
which include convenience and comfort, energy savings,
flexibility and enhanced safety and security. Wireless control
offers several distinct advantages as a method.
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With no communications wiring required, users realize lower
installation costs while installers realize easier
installation.
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Z-Wave wireless controls can operate independently of the
power supply by specifying RF models that use batteries,
further simplifying installation. Many of today’s controls
can last 10-15 years on a battery-based power supply.
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Easier integration between lighting and other home control
systems such as home theater, temperature control, motorized
blinds, garage doors, and security systems, for centralized
control of all systems that adhere to the common protocol.
These
advantages differentiate wireless control as a method for new
construction but particularly for retrofit or remodel
applications in existing homes. As the technology continues to
develop and costs are reduced, manufacturers believe demand will
continue to increase in the residential market.
“Nearly
anything that you control by hand can be controlled using Z-Wave
technology with a number of benefits,” says Wijgergangs. The
promise of wireless home control is convenience and comfort, a
simpler lifestyle. “For example, the lights in the home can be
programmed to come on when the garage door opens, ensuring the
user doesn’t walk into a dark house. Another example from a
convenience perspective is a Z-Wave-enabled home theater system,
where once a movie starts to play, the blinds go down, the
lights dim and the room becomes ‘movie-friendly.’”
Wireless
control is not without disadvantages. One area of concern with
wireless control networks, particularly for the home, is RF
interference from other devices such as security cameras and
baby monitors that may operate in the same frequency range.
Manufacturers are increasingly taking such potential issues into
account, however.
“Because
radio frequency is inherently an open system—that is, the
control communication cannot be isolated from the outside
world—it must rely on a clean radio wave environment,” says
David Szemborski, Product Manager for Genlyte Controls.
“Further, it is dependent on available radio frequency bands. We
have already had the military reclaiming one of the bands used
for consumer devices including garage door openers and lighting
controls.”
The ZigBee Protocol
ZigBee is an open-source protocol (IEEE 802.15.4) that
offers significant promise for nonresidential building control
applications and is supported by the ZigBee Alliance of
manufacturers, an alliance of more than 100 manufacturers
including Philips Lighting, Motorola, Honeywell, Samsung
Electronics, Invensys and Mitsubishi Electric. ZigBee is
relatively new and no products are commercially available as of
the time of writing, although a number are in development.
According to Sandoval, ZigBee offers mesh topology, high node
count, moderate bandwidth (192 Kbps), moderate range (100-1000
ft.), low power consumption, high reliability, AES hardware
encryption, and a high level of scalability.
New wireless control technologies promise strong utility
for commercial applications, providing the benefits of lighting
automation without dedicated communications wiring. Courtesy of
Advance.
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