All smart home appliances depend on connectivity with a device, app, or hub. For integrating a connected home, Wi-Fi is seen as a ubiquitous choice. Certainly, when you’re buying Alexa or Google Home-compatible devices, it’s good to have them with a secure Wi-Fi pairing. That can easily go with your existing home router and you don’t have to buy a separate smart hub to add the devices in.
But Wi-Fi has its limitations. The devices that run solely on Wi-Fi need frequent charging. Think of laptops, smartphones, and even smart speakers. Besides, they aren’t capable of self-discovery and you have to manually enter the password for each new Wi-Fi device. If for some reason Internet speeds are lower, it can turn your entire smart home experience to a nightmare.
When it comes to wireless connectivity, Bluetooth has always been a second choice to Wi-Fi. Yet, in recent few years, we have seen an exponential rise in the usage of another IoT protocol – Zigbee. Philips Hue, a trendy smart lights maker, was an early proponent of using Zigbee open interoperability standard. Many smart home companies have followed suit, and Zigbee is today nearly as prevalent as Wi-Fi.
Let’s explore the relative pros and cons of using Zigbee or Wi-Fi. Knowing these differences is crucial as it can greatly influence your purchase decisions for specific smart home products.
Zigbee vs. Wi-Fi: Basic Differences
Founded in 2003, Zigbee protocol is an open-standard communication based on IEEE 802.15.4 which also governs other low-rate networks such as 6LoWPAN and Thread. The ‘bee” in Zigbee name was inspired from the zig-zag dance of honeybees while they pass messages in close proximity to one another. Zigbee was therefore, conceived as a low-power, low bit-rate, short-range protocol in 2.4 GHz band for efficient communication across a “mesh” of devices.
Zigbee’s maximum speed is 250 kbps which is a pittance compared to Wi-Fi but that’s not the reason for its popularity. As shown, the Zigbee device object (ZDO) sits on a higher application layer compared to the Physical (PHY) layer where the 2.4 GHz (and 915 Mhz) radio operates. Such a design is suited for longer battery life characteristic of Zigbee devices. Therefore, Zigbee devices consume orders of magnitude less power compared to a Wi-Fi radio device which operates on a similar 2.4 GHz spectrum.
Founded in 1997, Wi-Fi is a wireless network protocol based on the IEEE 802.11 standards. Its bandwidth is much higher, ranging from 32 Mbps (802.11a/b/g) to 700 Mbps (802.11ax), also known as Wi-Fi 6. Originally used to connect computers and networking devices in a local or wide area network, Wi-Fi has quickly evolved to support communication for smartphones, smart speakers, smart television, and other smart consumer home appliances. Wi-Fi standards are maintained globally by the Wi-Fi Alliance which ensures compatibility and interoperability of Wi-Fi products.
Unlike Zigbee which uses a “Coordinator” (Hub) device to join the Zigbee nodes, Wi-Fi is managed using wireless routers, Mi-Fi devices, or portable hotspots. Also unlike Zigbee, Wi-Fi is designed to consume more battery power and most commercial Wi-Fi compatible devices have a Wi-Fi chip for communication with the wireless access point, i.e. the Wi-Fi router.
The technical differences among Wi-Fi and Zigbee products are much more detailed than this. That goes to explain the major advantages and disadvantages each technology has with respect to the other. And why each is suited for a different kind of smart home application.
Zigbee vs. Wi-Fi: Where Zigbee is Better
1. Backward and Forward Compatibility
As per the Zigbee Alliance, one of the key highlights of Zigbee certified products is that they are designed to be compatible with legacy and future versions of Zigbee. The backward compatibility is allowed for the latest Zigbee 3.0 devices to merge back into your existing network. At the same time, older Zigbee devices can join Zigbee 3.0 networks based on the security policy allowed, and through over-the-air updates. With Zigbee if you already have smart home devices deployed in the network, you can be sure they will be compatible with the new Zigbee nodes.
Wi-Fi certainly does not have this advantage entirely. While you can use Wi-Fi 6 with previous standards, the forward compatibility doesn’t exist for devices designed for earlier versions of Wi-Fi.
2. Fault Tolerance
Both Zigbee and Wi-Fi follow different network topologies. Zigbee is arranged around a mesh where each node not only talks to the “Coordinator” but also with other nodes, leading to better fault tolerance. If one of the nodes is disturbed/damaged, it does not affect the remaining network. There’s a reason industrial automation (IIoT) uses networks such as Zigbee and Z-wave. The same benefits apply to smart homes.
A Wi-Fi network is generally arranged in a “star” topology (although it’s possible to do a Wi-FI mesh) with a router and repeaters. If one of the Wi-Fi repeaters in the network is damaged, then the fault will be passed to all the end node devices connecting to it.
3. Extending the Reach
Instead of manually adding repeaters as in a Wi-Fi network, Zigbee allows each Zigbee node to act as a repeater. As long as your ZDO is powered-on, it can serve as a relay point to transmit signals to the end node. Therefore, the more Zigbee devices you buy, the further you’ll extend your reach (although you should be concerned about signal disruption with too many Zigbee nodes).
4. No Need to Enter Password Every Time
With Wi-Fi networks, it can be tiring to enter a password every time a new device is added. It can feel more tedious with any device disconnection or other service issues.
On the other hand, Zigbee protocol support a feature called “device discovery services” because all Zigbee endpoints have unique hexadecimal device IDs, as shown below for a Philip Hue motion sensor. The client node is automatically discovered and connected in the network which removes the need to enter passwords manually.
5. Less Dependence on Cloud
As compared to Wi-Fi compatible devices, Zigbee end node devices have less dependence on cloud updates. While they do service over-the-air (OTA) updates, all Zigbee devices operate on their own mesh. This way they are vendor-agnostic. So, if the device maker stops supporting one or more features, it will not affect the field operations of existing deployments. Smart hub companies such as Hubitat go even further in using Zigbee to achieve independence from vendor and cloud control.
6. Support of Smart Home Hubs
Zigbee-compatible devices are easily supportive of smart home hubs. If you want to unify all the devices in your network, you need an effective smart home hub. And that can only happen when all the end node devices including sensors, bulbs, cameras, and accessories seamlessly connect and communicate clearly. That is why most smart hubs including Alexa-speakers have been made Zigbee compatible.
Of course, if you consider the smart home hubs provided by Apple, Google, and Amazon, they would extensively use Wi-Fi as well. But many hubs such as Insteon, Hubitat, or Control4 use Zigbee. Smart home owners seeking centralized operations through a hub would easily benefit from more Zigbee devices.
7. Low Power Devices
As explained above, Zigbee devices have been designed to run on low-power mode. This gives more standby time and more continuous operations. The longer battery life comes at the expense of bit rate, and at a max speed of 250 bits/second, you can’t use Zigbee for anything else but home automation.
8. Types of Devices Supported
Zigbee is becoming a universal choice for HVAC Control, Light Management, Energy Management, Light monitoring, environmental monitoring, and commercial buildings. The following are a range of Zigbee-compatible devices available with Tuya Smart, a leading home automation maker. Some of the applications commonly used with Zigbee include wireless and multifunction gateways, smart switches, dimmers, LED bulbs (e.g. Philip Hue lights), and other multipurpose components. You can’t afford for them to become non-functional due to Wi-Fi speed issues.
Where Wi-Fi is Better than Zigbee
Zigbee smart devices can be notoriously more expensive than Wi-Fi devices designed for the same basic purpose. This is because Wi-Fi devices have been in the market for way long. Also, for a given application, more device manufacturers may support Wi-Fi devices rather than Zigbee. This can limit one’s choices. However, the cost of Zigbee is somewhat mitigated by the fact that you don’t need to purchase repeaters separately. Each Zigbee device serves as an extension repeater.
The challenge with most Zigbee devices is that they operate better in short distances due to the shortwave physics. In comparison, long-range Wi-Fi can support distances up to 100 meters. This means they are less prone to signal interference compared to Zigbee devices. The Zigbee signals happen to be weaker anyway, which can increase the distortion and signal deterioration if there are way too many Zigbee devices in a short range. Modern Wi-Fi networks have overcome this barrier with quality-of-service improvements, making them less vulnerable to signal issues.
3. Device Integration
It’s easier to integrate Wi-Fi connectivity on an IoT device compared to Zigbee. A Wi-Fi chip is assembled on almost any IoT board which comes equipped with a Wi-Fi radio helping connect to any wireless access point. Device integration using Zigbee is much more difficult because one needs a Zigbee sensor which has to be separately purchased and integrated into the IoT board.
Compared to Zigbee, Wi-Fi offers higher security. Since Zigbee is an open-standard technology, Zigbee devices of different vendors are more compatible with each other than Wi-Fi. For example, you cannot use a Tuya Smart mobile app to run Amazon Alexa skills on Wi-Fi unless you had already synced the apps before. All Zigbee devices, on the other hand, speak the same universal language. So apps by different vendors are cross-compatible, which introduces greater security risks.
5. Consumer IoT Applications
Offering much higher bandwidth, Wi-Fi is definitely more suited for consumer IoT applications such as smart speakers, video calling using Facebook Portal, smart nightstands, and other everyday activities. You cannot use Zigbee to send even an email so it’s not suitable for any consumer IoT applications which may require continuous user interactions. They are really more suited for smart home automation alone.
Wi-Fi vs. Zigbee: Which is Better for Smart Homes?
In the above comparison of Zigbee with Wi-Fi, we have explored their respective advantages and disadvantages. While more points are in favor of Zigbee if you’re looking for greater autonomy and freedom from vendor control, it’s too early to declare Zigbee our contest winner. Both networking protocols have their own acceptable criteria for smart home use. If you just started out building a smart home, it may serve you better to go for Wi-Fi compatible devices which sync with Alexa, Google Home, and other speakers. Also, you don’t need to buy a smart hub.
But if you want several modifications in your home with smart lights, curtains, switches, thermostats, and other building automation activities, having Zigbee-compatible devices and a smart home hub will better serve your needs. In other words Zigbee is for the more advanced smart home user.