Tech expert Britta O’Boyle details the smart home protocols worth keeping an eye on and where their futures lie.
The smart home is a minefield of different protocols, standards and alliances, all of which set out with the aim of making everything easier to control behind the scenes. Ask a customer what controls a smart home and many will probably suggest Alexa, Google Home or Siri – and they wouldn’t be completely wrong as all three are consumer-facing controls, alongside various apps.
Few customers will probably know a huge amount about the underlying technology within a smart home, however – the protocols and standards that mean a smart thermostat can talk directly to a boiler, or smart IKEA lights can talk to the Philips Hue app, making control easier for the end user. And why should they know? Consumers just want things to work. As installers, however, it’s worth knowing a little about the various standards and protocols within the smart home so you can understand what works with what and recommend the right products.
With that in mind, we’ve detailed four protocols, standards and alliances worth brushing up on. You can also read all about another, Matter, in our separate article.
OpenTherm
OpenTherm has been around for a while so there’s a good chance you’re familiar with what it offers. In a nutshell though, it is a communication protocol and an interface specification designed for boilers and thermostats to effectively talk to each other. It allows for more efficient smart heating by enabling the boiler to adjust its water temperature based on digital information such as the actual room temperature, for example.
Simply put, it’s a common language that different manufacturers can use in their products, enabling mixing and matching of thermostats and boilers from different brands – as long as they both support OpenTherm as a minimum.
Besides communication, OpenTherm also allows manufacturers to add extra features on top of the basic functionality, such as setting hot water temperature, turning hot water on or off, or receiving weather information. These additional features are also standardised to ensure compatibility between different brands.
When it comes to the future of OpenTherm, a logical route will be for OpenTherm controllers to connect to a home bus system, of which there are multiple variants, including Zigbee. Bus systems are designed to network devices via a common data line, making it possible to centrally control various elements of the smart home – not just heating, but lighting, air conditioning and other electrical devices – via a central unit for more intelligent management.
Zigbee
Zigbee is one of the leading protocols within the smart home, helping smart home devices like smart thermostats, smart lighting and sensors – among various other elements – to talk to each other and to those using them (through apps and hubs rather than literally!). Wi-Fi and Bluetooth do some of this, but those standards aren’t great for meshing together multiple low-power devices throughout a home.
Zigbee meanwhile, uses the IEEE’s 802.15.4 personal-area network standard to communicate with other Zigbee devices, creating a mesh network where each interoperable device can communicate with the next and a centralised hub, reaching up to 100m indoors and supporting 65,000 devices.
Though not a definitive rule, typically wired devices like smart plugs act as Zigbee signal repeaters, with the potential to work over a huge area and pass on information around the
Zigbee mesh. Battery-powered devices, meanwhile, usually communicate directly with the smart home hubs rather than act as Zigbee relay devices.
Zigbee is currently on version Zigbee 3.0, benefits from 128 bit symmetric encryption so it’s pretty secure, and usually runs on the 2.4GHz frequency. It can pass data around at roughly 250kbps – which is plenty for changing a lightbulb brightness or reducing the temperature of a thermostat – but by using the 2.4Ghz frequency, there is a risk of some interference as that is the typical Wi-Fi standard too. A Zigbee Sub-GHz network is also available, however, meaning the Zigbee mesh network can operate on this lower frequency and offer improved range, as well as the ability to pass through walls.
Where things get a little confusing with Zigbee is that its makers – the Connectivity Standards Alliance (previously called Zigbee Alliance) – is also a huge player in Matter. Matter was set up to help manufacturers build devices compatible with those consumer-facing controllers like Alexa, SmartThings, Apple HomeKit and Google Assistant. Those devices won’t necessarily feature Zigbee by default – though Zigbee is supportive of the standard – but Zigbee also isn’t going anywhere anytime soon. Whether Matter properly gets off the ground or not, Zigbee has a great head start, can be found in new devices like the Amazon Echo Hub, along with around 2,500 others, so it’s worth knowing about.
Z-Wave
It wouldn’t be right to mention Zigbee without mentioning Z-Wave as the two are often discussed in the same sentence despite being separate protocols.
Similar to Zigbee, Z-Wave is a wireless protocol designed for communication within the smart home, creating a mesh network that enables devices to talk to each other and be controlled via a smart home hub. It also uses the same AES-128 symmetric encryption.
Unlike Zigbee, Z-Wave opts for low-energy radio waves – specifically the 800-900MHz radio frequency range – rather than the 2.4Ghz frequency. This means less chance of interference, but it also allows communication between smart home devices with a larger range than Bluetooth, and whilst using less power than Wi-Fi.
There are over 100 million devices on the market with Z-Wave inside, said to cover more than 70% of the smart home market. Smart water shut-off valves along with flood sensors and/or leak detectors have been named as some of the most popular of the Z-Wave devices out there.
There have been a number of improvements to Z-Wave since it first launched in 2004, with Z-Wave Plus (also known as Z-Wave 500 series), Z-Wave 700 series and Z-Wave LR all arriving over the years, bringing new features such as longer range and less power consumption. For the future though, there are plans to make Z-Wave open stack which will enable other silicon companies to hop on board, delivering even greater variety. Like Zigbee, Z-Wave is also supportive of the Matter standard, which could mean great things for the smart home in the future where everything plays nice, from the boiler to the lights.
Thread Speaking of Matter, there is one last protocol to mention that has an important role in the future of the smart home, and that’s Thread. It’s yet another wireless protocol, but this one is at the forefront of the Matter initiative with a number of Matter devices using Thread already available. This protocol also offers some differences to Zigbee and Z-Wave.
Thread is designed to connect all smart home devices together in a big old mesh network, but unlike Zigbee and Z-Wave, there is no need for a smart home hub to connect these devices. Instead, the devices just require a Thread border router to connect Thread devices to other IP-based networks, such as Wi-Fi or Ethernet.
You might think Thread border routers are hard to come by but they are more common than you may realise. Apple’s HomePod mini and the most recent Apple TV 4K are both examples, as are the Nest Hub Max smart display, 2nd-gen Nest Hub and the Google Nest Wifi mesh router – none of which are brand new devices.
Over 250 devices can be supported in a Thread network using a border router, its power efficiency is top notch and, like Z-Wave and Zigbee, Thread also uses AES encryption for security. The biggest benefits of Thread, however, are that not only could it allow a customer’s fridge to talk to their thermostat without a hub in the middle, devices are also self-healing so if one goes down in terms of connection, they don’t all go down, making for a more reliable smart home.
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