Battle Of The Networking Stars, Part One: ZigBee vs. Z-Wave

Now, two new wireless networking technologies are vying to take the place of Ethernet cabling for at least some applications in the digital home—specifically, the transport of sensor feedback and control commands.

While some proponents of the two technologies have chosen to support one over the other, all express agreement that both ZigBee and Z-Wave can change the way people use and interact with technology products in the digital home.

It also is believed that ZigBee and Z-Wave can do even more for integrators' bottom lines—offering new and expanded business opportunities, including additional services such as remote system and device management. Still, some integrators say they're hesitating before adopting these new technologies, preferring instead to wait until they are proven to be reliable and simple to use.

Creating Mesh Networks
ZigBee and Z-Wave both are wireless networking technologies for transmitting and receiving control commands, particularly for lighting, HVAC, security and access systems, as well as for sensors and automated draperies and shades. Both technologies also form mesh networks that are "self-organizing" and "self-healing," says Bob Heile, chairman of the ZigBee Alliance, the organization that oversees the development of the ZigBee technology.

In a mesh network, each node also functions as a router—finding, connecting to and communicating with the other nodes in a given network.

For example, a ZigBee or Z-Wave motion detector that is triggered may remotely switch on all of the networked lights along a specific path from room to room, or a ZigBee or Z-Wave thermostat in one room may wirelessly control a networked furnace in a distant part of the house. Although the thermostat may not know how to control a light switch, it can use the wireless radio built into a light switch near the furnace to find and communicate with the furnace, Heile says. "The lighting network just acts as a conduit," he says.

Moreover, if the usual conduit between two networked devices stops working, a new connection path can be forged automatically. For example, the thermostat may begin talking to the furnace through a nearby ZigBee or Z-Wave smoke detector if the light switch's radio fails. ZigBee and Z-Wave devices also have the ability to report information to a display device. If the battery in a ZigBee smoke detector is running low, it can show an alert on a ZigBee wall panel or on a ZigBee-enabled PDA, Heile explains. Both technologies also consume very little power and are able to work with battery-operated devices, providing years of battery life. Big Differences
While technically similar, ZigBee and Z-Wave are significantly different in a number of ways that have experts—including integrators and product manufacturers—taking sides.

The most important difference may be that ZigBee has been developed by the ZigBee Alliance, a standard-setting association composed of eight promoter companies—Chipcon, Ember, Freescale, Honeywell, Mitsubishi, Motorola, Philips and Samsung—and more than 180 member companies. By comparison, Z-Wave is a technology developed by one company, Zensys of Upper Saddle River, N.J. Zensys sells Z-Wave chips and software to companies that want to produce Z-Wave-compliant products.

There are more than 125 companies with such products already available or coming to market soon, and these products include universal remote controls and routers for personal computers, says Raoul Wisjergangs, vice president of business development and marketing at the company. These companies are in a separately run organization called the Z-Wave Alliance, which is responsible for ensuring interoperability among Z-Wave-compliant products and for promoting the technology. The Z-Wave Alliance is led by six companies: Danfoss, Intermatic, Leviton, UEI, Wayne Dalton and Zensys. Another difference, says Per Nathanaelson, CEO of Zensys, is that the Z-Wave Alliance is "purely focused on home automation. We do nothing else." Zensys also is planning to make Z-Wave work as an A/V device control technology in the future, Nathanaelson says. By comparison, ZigBee is aimed at the digital home market as well as at commercial and industrial users.

There are technical differences, too. First, while ZigBee offers a data rate of 250 Kbps, Z-Wave offers a data rate of 40 Kbps with its second-generation chip (recently introduced) and 9.6 Kbps with its first-generation chip. Products based on the second-generation Z-Wave chip are backward-compatible with first-generation Z-Wave products.

Second, while ZigBee mesh networks can contain up to 65,536 devices, Z-Wave mesh networks can contain up to 232 devices—although multiple Z-Wave networks can be bridged together, Nathanaelson notes.

Third, while ZigBee operates in the 2.4GHz or 900MHz frequency ranges on 26 channels, Z-Wave operates only in the 900MHz frequency range, and on only one channel.

The first products certified by the ZigBee Alliance—bearing a ZigBee Home logo—will be available by the end of this year, with a lot of new products debuting in 2006, Heile says. These will be intermediary devices that bridge the ZigBee control environment to other environments, such as an IR-to-ZigBee bridge, he says. In 2007, ZigBee will be built into consumer electronics devices such as TVs and DVD players, Heile predicts. One home automation product manufacturer, Control4, Salt Lake City, already sells "ZigBee-ready" products, including remote controls and lighting controllers, Heile notes.

Right now, there are 80 Z-Wave-compliant products available in the United States and Europe, compared with 34 when the technology debuted last January. By January, the number is expected to grow to more than 200, Nathanaelson says. More than two-thirds of the existing products have been available in the United States, and this will continue to be true as the Z-Wave ecosystem grows, he says.

Nathanaelson says integrators are an important distribution channel for the Z-Wave Alliance companies, but that retail also is an important sales venue. Each camp, ZigBee and Z-Wave, has dedicated supporters. ZigBee, like Ethernet, has the advantage of being a standard for wireless communications created by a consortium of companies, says Eric Smith, CTO of Control4. In the final analysis, Smith says, such standardized technologies defeat technologies developed by single companies unless the single company is one as dominant as, for example, Microsoft. "Even when IBM was pushing token ring [computer networking technology], Ethernet won, and we don't believe Zensys is IBM," Smith says. On the other hand, says Mark Walters, director of business development at Leviton Manufacturing in Bothell, Wash., "Z-Wave is mature. There is an ecosystem of manufacturers that are all developing products around the Z-Wave technology and they'll all be interoperable. ZigBee hasn't been able to get traction in the marketplace because it doesn't really know what it wants to be when it grows up."

Companies in the consortium are pulling the technology development in different directions, Walters says, adding that Leviton has participated in the developments of both ZigBee and Z-Wave.

Moreover, the Z-Wave technology is less expensive than the ZigBee technology, says Chris Walker, president of ControlThink, based in Salt Lake City. ControlThink in November will begin selling the ThinkBox, a $995 dedicated home-control server that uses Z-Wave technology to control lighting, HVAC and security systems. ThinkBox Custom, a version aimed at integrators who can create custom drivers and interfaces for it, will enter a beta-test phase in November.

What the Integrators Say
ZigBee and Z-Wave have some integrators excited enough to be considering them as the centerpieces of new business ventures.

"ZigBee has the potential and capability of having everything I would want out of a retrofittable control system," says William Maronet, president of ETC, an integrator in West Palm Beach, Fla. ETC is a dealer for Control4 and has been testing it in the homes of Maronet and another employee for a number of months. Although they have had to deal with occasional "processor lockup bugs," Maronet says, Control4 has issued regular fixes. Now, Maronet says he is planning to create a "retrofit division" of ETC centered on the Control4 products, and he expects it to be a very profitable division. Because a retrofit business generates profits based entirely on time and materials charges, it's not possible to lose money on the business, Maronet says. Maronet also says he's familiar with Z-Wave products but has not used them in his business.

Other integrators are a bit less enthusiastic about ZigBee and Z-Wave. Thomas Callahan, president of Sawyers Control Systems, Frenchtown, N.J., says before committing themselves to a new technology, integrators must be assured it will have legs. "We try to look for things that have longevity in the marketplace so that five years from now they will still be in the marketplace and we can still service it," he says.

Gordon van Zuiden, president of cyberManor, an integrator based in Los Gatos, Calif., agrees. Although "reliability and simplicity are the No. 1 and No. 2 goals of any install," Control4 products—and, by extension ZigBee—are not proven reliable. But he remains optimistic. "New technologies in general give us a lot of opportunities," he says. "The integrators that are aware of them put themselves in a better competitive position."