Smart Home System Types

As with anything that isn’t totally self-contained, what else it works with is very important in making a purchase decision. Otherwise, you are locked into a single vendor and are at their mercy as to what other products they sell. There are three main, modern types of wireless networks found in smart home applications. These are WiFi, Z-Wave and Zigbee. As a user, you don’t need to know the technical details and differences; just understand that they don’t directly interoperate. A Z-Wave device, for example, cannot communicate to a device or smarthome hub that uses WiFi or Zigbee. Many hub are multinetwork–supporting two more network types directly. The Hubitat Elevation hub that I use, supports Z-Wave and Zigbee devices as well as a wired connection to a WiFi router; so all three system types.

WiFi is really designed for performance, each generation having much high throughput than the previous, and not for low data rate but extreme battery life applications. Your leak sensor, for example, will hopefully sit idle for years without signaling a water leak and if it does, it is a simple leak/no leak condition. Z-Wave and Zigbee were designed specifically for those battery-operated, low data-rate sensor conditions. For example, some WiFi smart-locks are rated at 1-2 months between battery changes as opposed to Z-Wave/Zigbee devices often rated at 1-3 years between battery changes.

Why not WiFi Devices

Some modern smart devices use WiFi as oppose to a dedicated smart home protocol. That is fine for a few devices but I avoid WiFi smart home devices for three key reasons. Perhaps the most important is power consumption. Most smart home sensors cannot be connected to power and must run on batteries. Actuators on the other hand, usually need more power than sensors so either require a battery change every month or so or hardwired to power. The second issue is number of supported devices. While there is no specific limit on number of WiFi devices serviced by a router, there is often a software limit of 32 devices per router or RF band. That sounds sufficient until you start counting WiFi devices you already have–in my family everyone has a smart phone, an iPad/tablet, a laptop and a desktop computer. Add in several video cameras and I’m getting close to 20 WiFi devices. Not 32 but I only use WiFi for devices that need the bandwidth, such as video camera. Finally, WiFi devices are generally accessible directly from the Internet opening up a potential hacking risk. That isn’t to say a WiFi router couldn’t be developed supporting many more devices with great security but I haven’t found one yet. While the added security of having a hub that converts between WiFi and Z-Wave or Zigbee isn’t foolproof, it is a deterrent to casual hackers.

Where WiFi devices shine is ease of use with Alexa or Google Home or other cloud service. I don’t use a cloud-based service since I have no control over it. As I write this, a popular cloud-based smart home service has been “down” for a week and a half and just now coming back up, in spite of charging its customers a monthly fee. In recent times, some cloud-based services ran out of money and closed down. I doubt that Amazon or Google will run out of money but many smart home services are much smaller and less financially solid. And finally, a cloud-based services requires you Internet connection to be working and low delay.

And then there is Thread

It should not be surprising in technology that no company wants to give any competitor any advantage. So you will see several similar standards groups emerging and you will see companies hedging their bets, so to speak, by joining multiple, competing standards groups. And newer standards efforts can learn lessons from older standards or pivot to changing conditions. This standards posturing does not benefit consumers but it is the way technology develops. Or as the old saying goes, “the nice thing about standards is there are so many of them to choose from.” (Attributed to Andrew Tanenbaum but similar to a quote attributed to Grace Hopper.) And as someone working in computer networking since 1972 and wireless since 1975, I completely agree. Even though the Internet was developed for the slowest of networks and the least powerful of computers (just consider the situation of 1970’s technology), many engineers decide that the Internet is too complicated and invent something new and “better” (not invented here at its best). The Internet was designed to work well at speeds thousands of times slower than modern networks and with computers a million times less powerful than today.