As home control continues to generate excitement both within the industry and among consumers, more and more people are looking for straight answers on today’s enabling technologies. The following Q&A provides an overview of Z-Wave, one of the most highly regarded and widely supported home control technologies and how it “stacks up” against ZigBee.

What is Z-Wave?

Developed by Zensys, a provider of wireless networking technology for control and status reading applications, Z-Wave is a low-cost, two-way, wireless mesh network communications technology that enables consumers to monitor and manage their home controls easily, conveniently and securely from anywhere in the world.

Which applications are best suited for Z-Wave?

The Z-Wave protocol is designed for residential control systems. Typically these systems have between five and two hundred plus nodes, distributed around the home and garden. The system is designed for easy installation because homeowners install and manage the system themselves. A typical control node is a lamp, light switch, thermostat, remote control, or motor to run a garage door or curtains. The Z-Wave system is not only fast and reliable but also low cost, giving the mass market the ability to enjoy the benefits of home control systems.

Are there Z-Wave products currently on the market? What are they?

Today, more than 50 Z-Wave products are on the market, with more than 15 new Z-Wave products hitting the market in February alone. In addition, the range of Z-Wave enabled products has rapidly expanded from lighting controls to security products, access controls, smoke detectors, window coverings and other digital home products.

What kind of industry support has Z-Wave received?

Industry support for Z-Wave has been overwhelming. To consolidate this support, The Z-Wave Alliance was formed in January 2005. The Z-Wave Alliance is a consortium of leading companies in the home technology space, including Intermatic, Leviton and Honeywell, dedicated to solidifying Z-Wave as the standard for wireless home control products and ensuring interoperability between systems and devices for all members.

Do you get asked about ZigBee? What are the differences between ZigBee and Z-Wave?

We are sometimes asked to explain the differences between ZigBee and Z-Wave. The biggest difference right now is that ZigBee products are not available whereas Z-Wave has been in the market for over three years and has already been accepted by over 100 OEMs as their standard interoperable platform for residential control.

Will ZigBee succeed in the end because it is an open standard?

History shows that the market chooses new standards from many sources, not necessarily those such as ZigBee, that are “designed by committee”. The most important aspect of a new technology is to meet manufacturer and consumer needs at affordable prices.

There are many examples of so-called “open” standards that did not succeed – think of Home RF, RF-lite, Purlnet, and Firefly. What’s more, we would challenge the claim that ZigBee is a truly “open” standard. Membership of ZigBee is by invitation only and to receive the specification one needs to pay membership fees approaching $10,000 dollars per year.

Lastly, with multiple “stack profiles”, radio standards and frequencies, vendor specific application profiles, options in the stack, and ways of deploying security, ZigBee has not yet shown if and how interoperability between applications and vendors will be achieved – thereby ZigBee fails to deliver the key requirement for an “open” solution.

Why is Z-Wave a better standard than ZigBee for residential markets?

There are three main reasons why Z-Wave is a better standard for consumer markets: actual interoperability achieved between applications and between vendors, wide industry support from manufacturers of consumer products and lower cost

Does Z-Wave offer better interoperability than ZigBee?

Interoperability is the key factor for consumers. People want to buy devices from different manufacturers and know they will work together. Zensys is able to guarantee interoperability because Zensys and its partners have control over all the different aspects: radio, network protocol, device profiles, and certification.

Guaranteeing interoperability is much harder for ZigBee. ZigBee must ensure compatibility between radios, software stacks, and device profiles from a large number of vendors. What’s more, ZigBee supports multiple frequencies, both 2.4GHz and sub 1GHz. It is highly unlikely that consumer products will support both options for cost reasons. Consumers will be confronted with a basic level of incompatibility between ZigBee products operating on different frequencies

Why is Z-Wave lower cost than ZigBee?

The main reason is the choice of radio platform. Zensys uses standard FSK (frequency shift keying modulation) technology optimized for residential networks, whereas ZigBee uses the complex IEEE 15.4 DSSS radio. A second important reason is memory size. The ZigBee protocol stack is larger than Z-Wave. A third reason is the greater maturity of the Z-Wave protocol, which will allow Zensys to implement ultra high volume silicon architectures that will cut the cost of the chip in half by 2006.

ZigBee claims a better range for ZigBee 2.4GHz than Z-Wave. Is this true?

No. The Z-Wave sub-1 GHz FSK radio has a superior communication range compared to 2.4 GHz DSSS radios. There are two main reasons for this. First, the sensitivity of the Z-Wave radios is better than a 15.4 DSSS radio. Second, the physical propagation range of a 868/915 MHz signal is approximately 2.5 times the equivalent 2.4GHz signal.

Where will ZigBee find its niche?

ZigBee is targeting a very wide range of applications, including PC peripherals, personal health care, large commercial buildings, industrial plant monitoring, asset management, as well as residential controls. Many of these applications are NOT suited for ZigBee. Zensys believes ZigBee is best suited for very large commercial and industrial networks – with thousands of nodes in a single network – where interoperability with other systems is not of paramount importance.

Z-Wave, on the other hand, has the leading position in residential control markets because of its consistent focus on interoperability and low cost, plus widespread support from major consumer electronics manufacturers.