ZigBee vs Z­Wave – What’s the difference?

By Lars.  November 4, 2014 www.blog.securifi.com

We’ve had quite a lot of questions about what the differences are between ZigBee and Z­Wave and in this blog post we hope to be able to clarify things without involving too much of the underlying technical details. Some key points require a little bit of technical understanding though, but we’ll try to keep things simple.

For starters, ZigBee and Z­Wave transmit the data at different frequencies and this is one of the major differences between the two technologies. ZigBee is using 2.4GHz which is the same frequency that Wi­Fi, Bluetooth and many other devices are using. However, as it’s a low power technology, it’s only using a fraction of the bandwidth of Wi­Fi. Think of this as how much space is being taken up by any wireless transmission in a given range of available space, which is the frequency.

Z­Wave on the other hand is using a frequency that’s below 1GHz, although it varies by region and this is a drawback when it comes to buying sensors from other countries. We’ve already had some backers that weren’t aware of this limitation and purchased sensors from a different region than the one they lived in. A sensor from one region can’t talk to an Almond+ from a different region and this means it can’t be connected to the Almond+. Sigma Designs, the company that owns the Z­Wave standard has a chart on its website that shows most of the regions and the local frequencies used in those regions and you can find it here:

http://zwave.sigmadesigns.com/docs/ZWave_Frequency_Coverage.pdf.

Most, but not all, mains powered Z­Wave and ZigBee devices can act as a signal repeater. Z­Wave has a limitation of four hops, whereas ZigBee can go as far as 30 hops, although the more hops, the longer the latency, or delay, from the signal to go back and forth between the Almond+ and the sensor/device. This is something to keep in mind if you have a large home, or want to be able to reach sensors outside of your home.

One downside of ZigBee is the use of profiles. The Almond+ supports the ZigBee Home Automation (HA) 1.2 profile, whereas for example, something like the Philips Hue system uses ZigBee Light Link (ZLL). The two aren’t fully compatible and this is why the Almond+ can’t talk directly to Philips Hue bulbs. The good news here is that many of the ZigBee bulb manufacturers now offer bulbs that are also compatible with ZigBee HA 1.2, such as the GE Link bulbs. There are also plenty of other ZigBee standards that the Almond+ can’t talk to due to the different profiles used, such as ZigBee Smart Energy, a standard that is used in some mains power meters.

Z­Wave has better backwards and forwards compatibility in this sense and there are no profiles that will cause problems like the ones described above for ZigBee. We know some of our backers were concerned about the chipset used in the Almond+ as the Z­Wave Plus standard was recently announced. Although the Almond+ won’t be compatible with Z­Wave Plus as such, Z­Wave Plus sensors should still work with the Almond+ as long as we’ve added support for them.

Both technologies have their pros and cons, although at the moment in terms of retail availability, there are more Z­Wave devices than ZigBee devices. Over the past few months we’ve seen more and more ZigBee devices becoming available in retail and it looks like the two standards will start to balance each other out over the next couple of years in terms of retail availability as more and more manufacturers are starting to support ZigBee. Of course, with the Almond+, you’re free to use either technology, with the benefit of a ZigBee sensor being able to talk to a Z­Wave sensor and vice versa, with the Almond+ handling all the communication between the two standards.

Hopefully this helps explain some of the more confusing aspects of ZigBee and Z­Wave as well as some of the main differences between the two technologies. Do feel free to ask us questions if there’s something you’re wondering about, as it’s better to check with us than to purchase something that won’t work with your Almond+.