ZigBee is the name OF a new open-architecture wireless personal area network (WPAN) technology designed for linking devices that perform a monitoring and control function. For buildings, these devices can include anything from a simple light switch or thermostat to more complex security and life safety devices. Since ZigBee-compliant products are based on an industry standard and not any one company’s proprietary system, any building monitoring and control device that is ZigBee-compliant can be used. ZigBee could be the next big thing in building automation and the electrical contractor needs to be aware of this new wireless technology.
ZigBee is based on IEEE Standard 802.15.4 that was ratified in 2003, and provides a standard for low-powered digital radio frequency (RF) transceivers that operate primarily in the unregulated Industrial, Scientific, and Medical (ISM) Band at 2.4 GHz.
The ZigBee Alliance—which is now composed of more than 200 firms including Honeywell, Eaton and other manufacturers—subsequently developed a networking specification that includes network protocols and security based on the IEEE standard. This alliance’s specification for ZigBee-compliant products was finalized last year and will open the door for the introduction of ZigBee wireless building monitoring and control devices this year.
ZigBee is a self-organizing and self-healing network. Being self-organizing means that any ZigBee-compliant device that is introduced into a ZigBee environment will be automatically incorporated into the network as a node. The self-healing network capability means that if a node is removed or fails, the network will automatically detect the loss of the node and work around it.
One of ZigBee’s most important features is its ultra-low-power requirement. ZigBee devices have just two states: active and sleep. In the active state, these devices process, receive and transmit data. The time in the active state is very short because little information needs to be transferred to fulfill a device’s monitoring and control function. In the sleep state, the device is dormant using very little power until it needs to go active again.
As a result, ZigBee devices can be battery powered and the batteries in these devices can last months or years before they need to be replaced. Therefore, ZigBee monitoring and control devices do not need to be connected to a branch circuit for power.
Two other wireless technologies that have invaded buildings in recent years include Wi-Fi and Bluetooth. Wi-Fi has a bandwidth or data throughput of 11 megabits per second (Mbps) or 11 million bits of information per second and operates in the ISM Band like ZigBee. Wi-Fi has an effective operating range of about 300 feet.
Similarly, Bluetooth has become a common technology for networking computer peripherals and other devices such as wireless cell phone headsets. Bluetooth has a data throughput of 1 Mbps and an operating range of about 30 feet, which is sufficient for voice and data exchange between nearby peripherals.
ZigBee has advantages over both Wi-Fi and Bluetooth in building automation applications. It is much simpler than either Wi-Fi or Bluetooth, making it physically smaller, cheaper and easier to integrate into building products. ZigBee was designed for this specific application so it is better matched to building automation requirements, uses less power and is more economical than either Wi-Fi or Bluetooth. For these reasons, ZigBee is poised to be the dominant wireless networking technology for building automation in the future.
At first glance, it appears that ZigBee will have a negative impact on the electrical contracting firm because power and control wiring will no longer have to be run to individual building monitoring and control devices.
However, this does not have to be the case for the electrical contracting firm that understands this technology and how it can help its customers. Even though ZigBee may reduce the amount of conductor and raceway installed on a project, someone will still have to integrate the wireless monitoring and control devices with the physical building systems that they monitor and control.
These systems include lighting; energy management; security and life safety; heating, ventilating, and air conditioning (HVAC); and many others. Understanding ZigBee technology and how to apply it will help the electrical contracting firm meet customer needs and provide competitive advantage. EC
GLAVINICH is an associate professor in the Department of Civil, Environmental and Architectural Engineering at The University of Kansas and is a frequent instructor for NECA’s Management Education Institute. He can be reached at 785.864.3435 or firstname.lastname@example.org.