Imagine being able to gauge exactly when an apartment's refrigerator is about to fail or when a property's flowerbeds need watering. Maybe you'd like to control the thermostats in different units, running the heat or air conditioning only when residents are home. For those willing to dedicate the time and dollars, building sensors and controls that handle such on-site operations have long been available. Until recently, though, they were too costly and complicated for most multifamily companies to consider.

But that was before ZigBee. This wireless standard with the unusual name could lead to technology designed to allow property owners to monitor and manage building controls remotely. With ZigBee in play, building owners and managers could theoretically place sensors on everything from water pipes to air conditioner condensers to monitor their performance.

Joe Pryzant, owner and president of Pryzant Management, which manages five properties in Houston, uses Aqura—a ZigBee-based submetering solution from Wellspring International in Bristol, Pa.—to monitor water consumption and to bill units individually in some of his properties. (The system is based on wireless networking technology from the Ember Corp.) “It has worked dramatically,” says Pryzant, who has seen water costs go down—as well as associated labor costs incurred when maintenance had to be physically sent out to a unit to track a leak or problem—and conservation efforts go up.

Z-WHAT? Based roughly on the IEEE 802.15.4 standard for wireless communications at low data rates, ZigBee is a low-cost “standards-based wireless platform optimized for the unique needs of remote monitoring and control applications,” according to the ZigBee Alliance, a California-based group of companies that are working together to create and certify applications for the new wireless specification.

Here's how it works: Once sensors are placed on a water pipe or an air conditioner condenser, those sensors essentially become the touchpoints on what is known as a “mesh” network—that is, a network that spontaneously forms based on the nodes, or touchpoints, that are in place. Then, the data from the sensors can be automatically communicated wirelessly via radio communications, which carry all wireless transmissions.

This allows property managers and maintenance people to know in real time what's happening at a building. Sensors placed on a refrigerator's condenser, for example, could alert management that the appliance is starting to fail or needs maintenance work even when the resident is out of town.

For many residential and commercial property owners and operators, ZigBee couldn't have come along at a better time. Between energy costs and conservation concerns, owners and managers are eager to track and maintain appliances like refrigerators; control thermostats in individual rooms or units; ensure reliable facilities security; monitor and conserve water consumption; and control lighting and lawn sprinkler systems.

“I can see where there could be some applications for reading meters, Tech Specs controlling lights, and security,” says Tom McMurray, vice president of IT at Lane Co. in Atlanta, Ga., noting that properties could probably save labor costs as well if property staff had “the ability to remotely read meters rather than go to the meters to read them.”

For Pryzant, ZigBee-based submetering allowed his company to get smarter not only about water usage and costs, but also about residents and their habits. For instance, toilets in some of the larger units would leak periodically, resulting in astronomical water bills for the property. The firm used to have no choice but to send maintenance door-to-door to check for leaks. But with ZigBee sensors in place, management can “electronically locate where the problems are and repair them,” says Pryzant.

But Bob Heile, chairman of the ZigBee Alliance, says that wireless sub-metering is only the beginning for ZigBee applications, which could save multifamily owners and managers thousands of dollars annually. Pryzant saw his water costs at one property drop from $400 per day in 2000 to just $266 per day in 2003, after he implemented ZigBee-based submetering.