What is Z-Wave? The Secure Smart Home Protocol

A beginner's guide to understanding one of the most versatile and secure smart home protocols 

Eric H. - Founder, Inovelli

A Secure and Versatile Protocol, Z-Wave is present in hundreds of smart home devices.

What is Z-Wave?

Z-Wave is a wireless communications protocol (e.g., Bluetooth or Wi-Fi) used primarily for home automation, which is best known for its interoperability, (compatibility between multiple manufacturers, products, product versions, etc.) security, and ability to operate outside your Wi-Fi network.

Before being known as one of the main protocols in home automation, Z-Wave was created to be a lighting control system. Since then, Z-Wave has developed into much more and can be found in many smart home devices such as thermostats, light switches, wall plugs, outlets, sensors, and more.

Enabling devices to communicate, Z-Wave is a protocol that operates similar to how your smart TV connects to your router to access the internet via Wi-Fi, or how your phone connects to your wireless headphones via Bluetooth to listen to music. Z-Wave communicates information, automations, and more which ultimately power your smart home.

Large protocols require rules and regulations as to how that protocol is written. For Z-Wave, those rules are set and enforced by the Z-Wave Alliance, which certifies every smart home device using the protocol, to ensure compatibility (Z-Wave calls it, “interoperability”) between the various versions of firmware. In other words, if you purchase a Z-Wave device that was developed in 2005, it should still be able to communicate properly with a device developed in 2021 and vice versa. In addition, a Z-Wave device from Manufacturer A should work with a device from Manufacturer B and vice versa, allowing you to not be locked into one manufacturer’s ecosystem.

More Info: For more in-depth information about Z-Wave, feel free to check out the Z-Wave Alliance’s page about Z-Wave Technology.

What are the Benefits of Z-Wave

The three main benefits of Z-Wave are that it’s one of the most secure protocols in the market2, its radio signals operate outside of the 2.4GHz and 5GHz bands (so it won’t interfere with your Wi-Fi signals), and lastly, it’s one of the more robust protocols from a firmware standpoint.

Benefits of Z-Wave: Security, No Stream Interference, Products that Work Together, and a Mesh Network.

Security

Residential and commercial security providers (Alarm.com, Honeywell, 2GIG, ADT, Nexia) utilize Z-Wave technology in 90% of their products, allowing Z-Wave to dwarf all other technologies in this space 2. Without getting too detailed, Z-Wave uses AES-128 encryption to protect data transmissions, making it so that it would take one billion years using, “brute force” via a supercomputer to crack the encryption key3. In 2017, Z-Wave introduced Security 2 (S2), which further protects devices during the inclusion.

More Info: For more detailed information about Z-Wave Security and S2, there’s a great article written by the Z-Wave Alliance here.

Does Not Interfere With Wi-Fi

Especially today, more than ever, your Wi-Fi bandwidth is extremely important. At any given moment, you could have Netflix streaming, Amazon music playing, multiple phones/tablets surfing the net, and various other smart devices connected to your router. The last thing you want is to have is 100’s of smart home devices also connected, potentially causing traffic issues.

With Z-Wave being one of the only major protocols to operate outside the 2.4GHz and 5GHz bands (it operates on 908.42 MHz in North America and 868.42 MHz in Europe) it allows you to have your smart home on a completely separate frequency from your Wi-Fi network.

Firmware Interoperability and Robustness

Electing to make compatibility the backbone of the protocol, Z-Wave made it so that regardless of the manufacturer and regardless of the year the Z-Wave enabled device was produced, Z-Wave products should work together seamlessly. This is one of the founding principles of the protocol and one of the special qualities of Z-Wave – interoperability. Since this is a mature protocol, there is a lot manufacturers can do to give customers all sorts of customization options.

Robust products such as our Red Series Dimmer Switch (Z-Wave) have some unique features such as allowing you to set the default level based on the time of day, adjusting min/max bulb values, multi-tap to activate a scene, LED bar notifications (e.g., lights up red if your alarm is not armed, flashes purple if severe weather is on the way, etc.), and much, much more4.

You guessed it, Z-Wave offers a lot of benefits such as security, robustness and is a protocol that is established, making it one of the leading choices in home automation, but it’s likely not on people’s radar as it’s not as mainstream as Wi-Fi and Bluetooth. 

How does Z-Wave Work?

Z-Wave works by utilizing a specialized hub/gateway (e.g., SmartThings, Hubitat, etc.) to create a mesh network of devices that communicate with each other over the lower frequency, 908.42 MHz (whereas your Wi-Fi operates on either the 2.4 GHz or 5 GHz band). Small data packets are transmitted to and from the hub across the mesh, allowing for better range and speed than its competing protocols.

Looking at one the main differences between Z-Wave and Wi-Fi, we’ll find that where your Wi-Fi signal degrades as you move further and further away from your router, Z-Wave, if built properly, can spread the signal evenly throughout your house and beyond by utilizing its mesh technology.

What is Z-Wave Long Range? We’ll explore this in an upcoming article as this new version does not use mesh technology.

Prerequisites for Working with Z-Wave

  • Purchase a Z-Wave Hub (e.g., SmartThings, Hubitat, etc): a hub or gateway that has a Z-Wave radio (e.g., SmartThings, Hubitat, etc) is required to establish this mesh and foster communication between devices. We’ll be releasing an article with more information about what hubs support Z-Wave and more about each of them at a future date.

    NOTE: Z-Wave devices will not pair directly to Amazon Alexa, Google Home, or Apple HomeKit as those gateway’s do not have a Z-Wave radio built-in.
  • Z-Wave Certified Products: Make sure the device(s) you’re interested in is properly certified. This ensures it will work properly with your hub and with other Z-Wave devices. All of our Z-Wave products are certified with the Z-Wave Alliance. To check certification for your device and even region, please see the Z-Wave Alliance’s page here.

Understanding Your Z-Wave Network

Starting with Z-Wave is actually quite simple once you understand the terminology and architecture. Each device is assigned a Node-ID from the hub when the device is initially included to the network. In addition, the device lets the hub know what kind of device it is (e.g., battery or mains powered, light switch or bulb, etc.). From there the hub creates an internal map that has the routes to/from each device optimized and every time a device is added or deleted, the hub will refresh that internal map along with refreshing at certain intervals to account for moving nodes.

Below shows how mesh networking works. As you can see, in the first example, the Z-Wave signal does not reach the switch. The way to solve this is to add an additional device to the network to relay the signal to/from the switch and hub as shown in the second example.

Z-Wave Mesh Networking act as repeater devices. Smart Z-Wave light switches act as repeaters allowing your network signal to strengthen and extend further throughout your own smart home.

Figure 1.1 – Mesh Networking Examples (SmartThings User Interface Shown)

More Info: For a more in-depth look at how Z-Wave works (e.g., S2, Application Layers, Configuration parameters, associations, command classes, scenes, awake / listening node, sleepy node, OTA, mesh network, etc.), look for our article to be released in December 2021.

Hopefully this article has helped bring some light (pun intended) to Z-Wave.

References:

  1. Z-Wave Alliance 2020 Ecosystem Report - https://z-wavealliance.org/wp-content/uploads/2019/06/Z-Wave-Alliance-2020-Ecosystem-Report-FINAL.pdf
  2. Smart Security with Z-Wave - https://z-wavealliance.org/smart_security_with_z-wave/
  3. How Secure is AES Against Brute Force Attacks? - https://www.eetimes.com/how-secure-is-aes-against-brute-force-attacks

Notes: 

4. Check to see if hub supports these advanced features as not all hubs do. More info here.

Join the discussion in our Community! Comments for this specific blog can be redirected here.

by Eric H. Sep 14th 2021

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