ZigBee: Making Wireless Building Automation a Reality

Jan. 19, 2007
ZigBee is making it practical to embed wireless communications into virtually any commercial building-automation product

Building automation had been languishing, hamstrung by the lack of practical and affordable communications technologies.

But, a new ultra-low-power wireless networking technology called ZigBee is making it practical to embed wireless communications into virtually any commercial building-automation product - from lighting ballasts to HVAC systems to smoke and security alarms - all without the prohibitive cost and disruptive hassles of hard wiring.

ZigBee is an IEEE 802.15.4 wireless standard that enables equipment and devices to self-organize into wireless monitoring and control mesh networks that automatically configure and heal themselves. Moreover, ZigBee devices can operate for years on cheap batteries. ZigBee networks typically use a line-powered infrastructure and battery-operated end devices operating as sensors, light switches, thermostats, etc. These sensors often sleep for much of their life and wake up for periodic, timed status updates.

ZigBee is backed by more than 200 OEMs, semiconductor companies, and technology providers, including some of the biggest names in building automation. Just as Wi-Fi (802.11), ZigBee’s IEEE cousin, ensures interoperability between different vendors’ wireless LAN products, ZigBee aims to bring the same standardization and multi-vendor interoperability to monitoring and control networks. This is good news for commercial building owners who, in the past, have had to bet the farm on a single vendor’s proprietary building-automation system.

Perhaps ZigBee’s greatest virtue for commercial building owners is energy efficiency. Imagine the cost savings of being able to automatically monitor and control all lighting and HVAC usage based on occupancy. For example, the Westmont Hospitality Group, Canada, one of the world’s largest privately held hospitality organizations, is saving energy with ZigBee technology in several of its Comfort Inn and Holiday Inn properties in the Toronto area, and is evaluating a nationwide rollout to its other properties. When complete, Westmont expects to save more than $2.2 million in energy costs per year.

Another key ZigBee virtue is scalability. ZigBee is designed to scale to very large networks, supporting up to 65,000 devices. This scalability is achieved through mesh networking, where devices communicate with each other using the best available path for reliable message delivery. If one path stops working, a new path is automatically discovered and used without stopping the system operation. This long-term reliability is critical for many building-automation systems that are expected to last 20 to 30 years once installed. ZigBee also has excellent range; coupled with mesh capability, it’s well suited for even the largest office complexes, resorts, convention centers, etc.

Building owners have understandable security concerns when it comes to wireless networks. That’s why ZigBee was designed with strong security mechanisms that are critical in commercial buildings. The ZigBee standard requires a security policy to be designed into all ZigBee devices. It provides simple (yet strong) end-to-end security, is based on a 128-bit AES algorithm, and incorporates the strong security elements of the IEEE 802.15.4 standard. The ZigBee protocol defines security for media access control (MAC), network, and application layers.

ZigBee security also introduces the concept of a “trust center,” which allows devices to be introduced into the network, distributes keys, and enables end-to-end security between devices. The security mechanisms in ZigBee make it an excellent solution for protecting building-automation systems from being compromised.

Ravi Sharma is director of marketing at Boston-based Ember (www.ember.com).

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