Wireless radio frequency (RF) lighting controls, popularized for use in higher end residential applications, are emerging as a viable alternative to hardwired controls in commercial building spaces.
Wireless RF controls communicate using radio waves instead of dedicated communication wiring, providing the benefits of enhanced flexibility and easier installation in hard-to-wire applications, such as ceilings that are difficult to access, hard ceilings and buildings with asbestos-abatement issues.
Typical commercial applications include outdoor lighting, parking garages, warehouses and retrofits. One particularly advantageous application is incorporating advanced control strategies into existing buildings, where running wire between new control devices can be disruptive, cost-prohibitive or too difficult. Wireless communication enables devices to be installed and relocated with relative ease and lower cost.
Lighting control devices include sensors (occupancy sensors, photosensors), low-voltage relay switches, line--voltage controls, plug controls, hotel card switches and shade controls. Specifiers should be aware that manufacturers may take different approaches to their wireless RF control products.
A basic system in a small space might consist of two devices—say a ceiling-mounted occupancy sensor that includes an RF transmitter and a wall-mounted power switch that includes an RF receiver—with both devices built and programmed to have a common understanding of each signal. The device might operate on energy harvested from the environment or battery power. High-quality batteries have a rated life of 10 years.
The maximum distance between devices for effective communication is 30–100 feet, depending on the product and whether the signal must travel through open air or obstacles. Range can be extended by adding a repeater or by building a mesh network. Obstacles, such as walls and metal enclosures (e.g., installation in a metal junction box with a stainless steel faceplate), will reduce range, the extent of which will depend on the type of material: steel, wood, brick, cement and so on. An RF signal strength meter, also called a “sniffer,” can be used to test intended device locations prior to installation.
For devices to communicate, they must be built according to the same protocol: proprietary, ZigBee, Z-Wave and EnOcean. Manufacturers developed proprietary protocols to support their products. ZigBee is an open-source protocol (IEEE 802.15.4) that provides a 2.4 gigahertz platform that the ZigBee Alliance of manufacturers supports. The 900 megahertz (MHz) Z-Wave platform was developed by Zensys and is shared with partner companies through the Z-Wave Alliance, making this protocol a de facto open standard. And EnOcean developed its 315 MHz platform and shares it with partners through the EnOcean Alliance.
Some projects require multiple devices working together to handle complex loads and implement integrated control strategies. For these more demanding projects, wireless control devices may be integrated into a mesh network. In such a network, control signals are passed along from device to device, which enables low-power devices (that are out of range or have no direct path) to communicate with each other over long distances, without the use of repeaters. In a typical network, the devices will be configured so that any two devices can communicate using multiple, redundant paths—all devices being connected by at least two pathways—with the system automatically configuring the most efficient path and rerouting if a given networked device fails. Such a solution is easily scalable. If the system enables two-way communication, devices can acknowledge receipt and request retransmission of data to enhance reliability. Note, however, that mesh networks are more complex than nonmesh to configure.
Wireless RF controls can operate as stand-alone systems or be integrated with hardwired lighting control systems, building monitoring and control systems such as BACnet, LONworks, Modbus, DALI and TCP/IP (Internet), and other wireless devices. All wireless devices installed in an application should be FCC-certified and secure from intrusion and should not interfere with each other.
The control devices will work together much the same as they would if they were physically hardwired, but they must be programmed and mapped to each other so that they know to which signals they should be responsive and how they should respond. This increases complexity, as the control system will have to be set up and commissioned. The chosen system should provide a method for easily finding and identifying devices for installation, operations and maintenance. It may be beneficial to program the devices prior to physical installation as the operating range is reduced during programming. It may also be beneficial to install the wired receiver device first and then the programmed wireless device within 10 feet to ensure mapping.
DILOUIE, L.C., a lighting industry journalist, analyst and marketing consultant, is principal of ZING Communications. He can be reached at www.zinginc.com.