When I started acquiring smart devices for my home, my focus was on those that worked over Wifi (or Ethernet) – I wasn’t really aware of the likes of Zigbee, Z-Wave and other protocols that were out there. In particular, I avoided those that required the purchase of a hub or bridge, due to the higher upfront cost.
Now that I’m further along my smart home journey, I’m more open to considering a range of different protocols. They all have their advantages and disadvantages to consider.
Wifi (and Ethernet)
I’m grouping these together as devices that are visible to a standard home network and have their own IPv4 address. The majority of smart home devices use Wifi, as there’s usually no need to buy an additional hub or bridge. Therefore, set-up is usually easy (sometimes aided by Bluetooth), and their range is fine as long as they can pick up your home’s Wifi signal. It’s also very easy to connect these devices to cloud services.
In terms of disadvantages: Wifi primarily uses the 2.4 GHz frequency band, which is used by lots of things and so there’s a potential for interference. The ease of connecting these devices to the cloud can also be seen as a flaw; they’re more susceptible to being compromised by bad actors, and don’t offer as much privacy. Wifi is also quite power-hungry – devices that don’t plug into the mains will need their batteries changing more frequently.
Bluetooth
As mentioned, Bluetooth is often used with Wifi to initially provision devices, but some Bluetooth-only devices can be used in a smart home. For example, there’s my Bluetooth thermometers, which connect to Home Assistant. Compared to Wifi, power requirements are much lower and so Bluetooth is good for battery-powered devices. They’re also more private, as they can’t easily be connected to from the wider internet.
However, Bluetooth has quite a limited range – it’s designed to be a ‘personal’ area network and won’t reach across large houses. You can use a Bluetooth Proxy in Home Assistant to extend the range, and whilst these devices are cheap, you’ll need to be comfortable flashing custom firmware and will usually need to plug them in as they bridge to Wifi. Like Wifi, it uses the 2.4 GHz band and so interference is possible – especially with the lower signal strength. Bluetooth connections also tend to be between two paired devices.
Zigbee
Zigbee is a mesh protocol, and it’s used by a number of smart home brands such as Philips Hue and Ikea Tradfri, as well as UK smart meters. This means that all devices on the same network talk to each other, and so a network with lots of devices could theoretically be quite strong. Like Bluetooth, there’s additional privacy as these devices aren’t connected directly to the internet like with Wifi. It’s also more energy efficient than Wifi, so battery-powered Zigbee devices will last longer between charges.
The key disadvantage of Zigbee is that you need a bridge to link it to your home network. Manufacturers like the aforementioned Philips and Ikea will sell you a hub that does this, although you can also buy USB dongles. Therefore, there’s a higher initial cost as you have to buy a hub as well as your devices. And it’s another 2.4 GHz protocol, so could have the same interference issues as Bluetooth and Wifi.
Whilst Home Assistant has good Zigbee support, both natively and through the Zigbee2MQTT system, if you don’t have a separate hub then getting these devices into Google Home can be a very involved process. Alexa is a little easier thanks to the Emulated Hue integration.
Thread
Thread is based on the same 802.16 standard as Zigbee, but differs in a couple of ways. Firstly, devices on a Thread network have an IPv6 address. Secondly, Thread is a simpler protocol that focuses just on being a mesh network with Matter taking over the device APIs. The benefit of integrating with Matter is that, unlike Zigbee, you may not need a separate bridge for Thread devices. A number of smart speakers from Google, Amazon Alexa and Apple can also act as Thread Border Routers, so it’s possible that you’ll already have the infrastructure in place in your home for Thread devices. Like Zigbee, Thread is a mesh network, and by using Thread Border Routers, the devices have a degree of separation from the wider internet that should improve privacy and security.
The downside is that Thread is still pretty new, and so there aren’t many Thread devices out there yet. You may also find that each device that incorporates a Thread Border Router creates a separate Thread mesh network. Home Assistant can be configured to join a preferred network, but it can be a bit of a faff. Ideally, they should all make one big, strong mesh network across your home, but we’re not there yet. And, once again, we’re dealing with a 2.4 GHz protocol here.
Z-Wave
Z-Wave sets itself apart from the aforementioned protocols by being on the lower 800-900 MHz frequency range. These lower frequencies have a longer range, and so are more suited to larger homes, but also avoid the interference of the 2.4 GHz band. Like Zigbee, it’s a mesh network, and should have similar privacy and security benefits by not being connected directly to the internet.
This also means that Z-Wave has the same disadvantage as Zigbee in that you’ll need a bridge to expose these devices to your home network. Furthermore, Z-Wave devices tend to be more expensive, so the upfront cost is usually higher than other protocols mentioned here.
RF and Infrared
I’m including these for the sake of completeness, but they’re not ‘smart home protocols’ in the same way as the above. It’s possible to connect the likes of Home Assistant to bridge devices that can communicate over Wifi and 433 MHz RF or Infrared. These will typically be doorbells or remote controls for devices that don’t connect using any of the above. But setting them up can be trial and error, and involves detecting and interpreting codes to trigger automations.
If you’re building a smart home system, then a bridge may be useful to bring existing devices in that don’t support standard smart home protocols. But if you’re looking to buy new devices, stick with the ones above.
