ZigBee and Z-Wave may open the door to widespread use of RF wireless control in commercial and residential applications
Lighting automation has been demonstrated to generate significant energy savings, increase flexibility, and influence worker satisfaction and productivity. Many types of lighting automation systems consist of a hierarchy of devices that are connected using low-voltage communications wiring. But new technologies are now being commercialized that should redefine wireless control by dramatically expanding its utility in both commercial and residential applications.
Wireless controls, which communicate either using a radio frequency (RF) or powerline carrier method, eliminate the need for dedicated wiring, thereby theoretically providing lighting automation's benefits at a significantly lower installed cost. RF wireless control has proliferated largely in residential applications to date. In these spaces, wireless control offers several distinct advantages, such as:
With no communications wiring required, users realize lower installation costs while installers realize easier installation.
Battery-powered wireless controls can operate independently of the power supply, further simplifying installation. Many of today's controls can last 10 to 15 years on a battery-based power supply.
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.
Meanwhile, demand for wireless control solutions in commercial applications will increase dramatically in the next several years, according to William Sandoval, business development manager — digital systems for Philips Lighting Electronics and the Advance division. He points out a number of advantages for RF wireless control as a means to achieve the benefits of lighting automation in a commercial setting:
Reduced capital and operating expenses. Wireless controls can save as much as 30% to 40% on installation and material costs compared to a wired control system. This will make wireless control an attractive option for retrofit projects as well as new construction. In addition, wireless technology makes it easier to maintain systems, as the owner can replace devices one to one without involving control wiring.
Flexibility. Wireless technology allows mobility; in a dynamic building where changes occur often, wireless technology allows the owner to move devices or group devices without changing wiring.
Scalability. Devices can be easily added to and removed from the system to account for future needs. Wireless also provides a suitable platform for incorporating new technologies.
True building integration. Wireless technology enables easier integration between lighting, HVAC, security, and other building systems that incorporates equipment and environment monitoring.
Centralized and decentralized intelligence. Controls can receive commands from a central computer and can also interact with each other independently, increasing responsiveness. Devices can also engage in two-way communications.
Personal control. Wireless control permits each occupant to be able to control his/her local lighting and temperature without location restraints.
RF control systems. When evaluating existing and new technologies, a number of questions are relevant:
What will the topology, or layout, be for the network of devices?
What's the communication range for each node, or device, in the network?
How much power does the system require?
What's the bandwidth and speed that's possible for transmission of data?
Is there a protocol, or common language, that enables multiple vendors' products to be interoperable in the network?
What are each option's comparative advantages and disadvantages?
What does the system cost?
Each of these points of evaluation in turn can be related to the protocol used, as the protocol affects the design of control devices.
Bluetooth and WiFi, two of the first open-source wireless protocols that use a star topology, in which all devices on a network are connected to a central computer, 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. In a mesh network, each device on a network is connected to and can communicate with every other device, increasing reliability and flexibility.
“Mesh networking protocols promise to provide new levels of system performance,” Walters 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 a de facto 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. Z-Wave products are commercially available and have been shipping since 2003.
According to Walters, Z-Wave offers 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 is also useful for small-scale commercial applications as well.
Raoul Wijgergangs, vice president of business development for Zensys, confirms that more than 90% of products designed to operate using the Z-Wave protocol are for residential applications — lighting and, theoretically, any other control device.
“Nearly anything that you control by hand can be controlled using Z-Wave technology with a number of benefits,” says Wijgergangs. “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.’”
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, a group of more than 100 manufacturers. ZigBee is relatively new and no products are commercially available as of the time of writing, although a number are in development.
ZigBee offers mesh topology, high node count, moderate bandwidth (192 kbps), moderate range (100 to 1,000 feet), low power consumption, high reliability, AES hardware encryption, and a high level of scalability, according to Sandoval of Philips Lighting.
Based on these characteristics, some manufacturers see ZigBee as more suitable for commercial than residential applications, with optimal utility in large-scale commercial environments.
“It appears that protocols that are public and open will, in the future, be ideal for commercial applications,” Sandoval says. “Today, there are very few open protocols, such as ZigBee and BACnet, in the marketplace, but they are starting to take command. Customers like options, and open protocols allow for those options. In addition, customers do not want to be tied down to a single vendor. In the wireless arena, ZigBee, as an open standard, will allow other devices to integrate and interoperate so that building owners can choose how, why, and when to use a specific vendor.”
He adds that the possibilities in commercial control are endless, but it will take time for new technologies to penetrate the market. Sandoval believes wide adoption will occur in 2 to 3 years. The first customers, he says, will likely be applications such as commercial A-grade buildings, hospitals, and big box retail stores.
Walters sums up his view of Z-Wave and ZigBee. “Z-Wave systems place the emphasis on low power consumption to allow for battery-powered devices while maintaining excellent range, node count, and sufficient bandwidth for residential control,” he says. “ZigBee provides greater bandwidth and node count at the cost of range and power consumption, and is more suitable for commercial applications. Both of these technologies promise reliability and attractive price points. Both emphasize low power consumption so that battery-powered devices can be used, providing application solutions such as ‘peel and stick’ occupancy sensors. Finally, there are powerful, flexible, affordable technologies that can be used to bring high-performance automation to the mass market.”
DiLouie is the communications director for the Lighting Controls Association and principal of ZING Communications, Inc. in Calgary, Alberta, Canada.