There’s a lot of signals potentially going through my head.
The Internet Of Things™: WiFi, Zigbee, Z-Wave, to say nothing of more traditional radio-controlled junk…there’s potentially a lot going on in the airwaves of my house. And that doesn’t even touch the older X-10 protocol (which communicates over your house’s electrical wiring) or proprietary stuff like Insteon (which uses radio and power wires) or HomePlug (which shoehorns other stuff like IP and phone and AV over your house wiring). It’s a big confusing mess. I’m trying now to get less confused.
(The following is specifically focused on home automation and control: some of the stuff isn’t actually true for other uses of the technology under discussion.)
Wifi: We all know what this is. You need a Wifi access point, router, or something to make it all go; Wifi devices don’t (usually don’t. Pedantic nerds can step off. In the real everyday world they don’t) talk directly to each other. You generally need a PC or phone app to talk to your Wifi-connected home control gadgets. And your communication with them is usually not all inside your own house: you talk to a server somewhere on the Internet that then talks to the light switch next to you. Which is cool, because you can control that light switch from Stuttgart as easily as from the rumpus room. But annoying because if your Internet connection fails, you might as well be in Stuttgart; you’re not turning off the lights in the rumpus room. And potentially scary, because if your online security (or the security of the people running the server) is compromised, some guy in Stuttgart could have control of your light switches. And locks. And if you’re not careful when purchasing you could end up with light switches you have to pay some company every month for the privilege of turning on and off. And there’s also the need to be concerned about what happens if the company you bought the light switch from goes under. Suddenly that server somewhere on the Internet stops serving and your light switches are expensive paperweights. (Really very few home automation things are actually straight Wifi. Most are Z-Wave; see below)
ZigBee: It’s a fantastic concept. ZigBee devices actually talk directly to each other in what’s called a Mesh Network. So a ZigBee lightbulb could be set up to turn on when a ZigBee light switch says “on”, and the Internet need not be involved at all. and it doesn’t matter if the bulb and switch are directly in range of each other: as long as they’re in range of other devices in the network, the signals will be forwarded along until they reach their target: that’s the “mesh” part. The problem is that there are not (hardly) any ZigBee light bulbs. Or light switches. The ZigBee Alliance (the governing body/glee club for all things ZigBee) lists several ZigBee certified switches. But I can’t actually find any for sale in the wild, let alone anything else like sensors and so on. ZigBee has been broadly adopted by industry and electronics hobbyists. You can get ZigBee board to attach to your Arduino project. You can get warehouse lighting fixtures that use ZigBee to communicate with each other and the occupants of the warehouse. They do amazing things, like only turning on if the light level drops, so saving money by not lighting the warehouse when the skylights are sufficient. And complaining to their owner when the bulb burns out. Or only lighting up where there are people working. And so on. And a lot of ZigBee-enabled thermostats exist. And ZigBee enabled power meters, in some areas. Which will in the future (and for all I know in some areas right now (but not mine)) allow the power company to turn your AC to a warmer setting if it will prevent a brownout in your area. Cool stuff. But for consumers to use at home to make their actual home lives easier? Slim pickings.
Z-Wave: Same idea as ZigBee. In fact so similar that I initially thought the one was a variant of the other (the Z in both names didn’t help). But they’re not; they’re competing. And (in the home arena) Z-Wave is clearly winning. All the Internet Of Things things you can buy down at Home Depot or wherever, they almost all use Z-Wave or Wifi (except a few thermostats that have Wifi and also ZigBee, and Lowes’ Iris system, that seems to use both ZigBee and Z-Wave). There are a few issues with the way it is implemented, though. In order to make the jump from your home Z-Wave network to the rest of the world (and let you turn on your lights from Stuttgart), you need to have a Z-Wave to Internet bridge of some kind (naturally). Which then talks to a server on the Internet, and so on see above as for Wifi. A lot of the people selling the bridges want to charge you per month to use them. But (I think; still researching) if you’re careful you can buy a Z-Wave bridge that you can talk to locally, so if the provider goes down you are not totally stuck. And one or two of them don’t charge per month for Internet connectivity. And while a lot of the people selling Z-Wave want you to feel locked in to buying all your Z-Wave stuff from them, it’s actually mostly open and (again, if you’re careful) you can buy a bridge that will talk to most anything. So again, if the people your bridge talks to go under, you have a problem because you’ll have to buy a new bridge, but your devices will likely all work with the new bridge. You’ll be spending the day re-networking them all and setting up all your presets again, but there is a way forward.
The main advantage seems to be that Z-Wave devices declare themselves to be members of one or more simple classes of devices: “I am control device”, “I am a lighting device”, “I am a thermostat”, etc, with standard in and out software controls. Which makes programming the glue that makes them all talk and control each other much easier. Whereas ZigBee seems to mostly be a communication platform, and the devices are left to their own devices in terms of how exactly they talk to each other. So each ZigBee thing needs to know a lot more about each other ZigBee thing it needs to talk to. Which makes them more flexible and powerful, but less easy to set up and a lot less easy to make interoperate: every time a new light bulb comes out you might need to give your light switch a software patch before it could control it. Which is not something the average home user is going to be up for.
(There’s also Bluetooth LE, which lets your phone directly control stuff nearby. But that’s only useful if you’re nearby the stuff you want to control. So far the only home control stuff I’ve seen that uses it is locks. It seems well suited to that application, as long as you don’t ever want to unlock your house from Stuttgart.)
Thermostats are a particularly confused area. There are now several Internet-connected thermostats that use Wifi. And some ZigBee/WiFi models. And many Z-Wave models (that expect you to control them through the Z-Wave bridge so mostly don’t have WiFi themselves). Thermostats are what first dropped me down this rabbit hole: I wanted Nests. Now I’m pretty sure I don’t want Nests, but the field is so open and confusing I’ve got a lot of work ahead to figure out what I do want.
The basic problem with being able to control your stuff from the Internet is network addressing. Most people’s home Internet connection does not have a stable IP address the whole world could memorize. It changes every once in a while. Or it could, anyway. A web site or mail server or whatnot has what’s called a “static address”. That is, it doesn’t change. For reasons that are partly marketing and mostly technical having to do with the Internet being about to run out of addresses, a static address costs a lot more and you have to ask for it special. The upshot of that is that there’s no way for the app on your phone to know the address of your home and the light switch therein. The solution almost everyone has settled on is that your light switch logs into a server on the Internet, and you log into the same server, and the server mediates the connection between you. Which means that many people can control their lights over the Internet while taking up only one static address (the one on that server). But it also means that if that one server goes away, many people are screwed. And if that one server is compromised, many people are vulnerable. There are astonishingly cool possibilities with this model, to be sure. There is the possibility to do really nifty stuff by integrating your accounts at many different Internet sites to do complex real-world things based on other real-world and Internet events. There are a couple of websites that are starting to do that; the most popular seems to be IFTTT (If This Then That). For instance I could set up my porch light to turn on whenever a package for me is marked by UPS as “Out For Delivery” and turn it off again when UPS marks it “Delivered” (and send me a text message with a picture of my front porch so I can see the box waiting there). I could use an app to use the GPS on my phone to automatically let my breadmaker know when I am heading for home and have fresh bread waiting for me when I walk in the door. Or tell the dryer not to finish drying my clothes until I’m on the way home so I can pull them out and hang them while they’re warm and unwrinkled. You get the idea: breathtaking possibilities to make our lives infinitely more effortless and easy. But it’s early days yet and beyond turning your lights on and off from Stuttgart it’s all mostly theoretical, and there are a lot of technical and conceptual hurdles to overcome.
Right now instead of The Internet Of Things and ZigBee, Z-Wave, and all that what I have is a little remote with a little antenna that sits on my bedside table and controls three radio-controlled outlets, and lets me reboot my Wifi router without leaving my bed. (Which I have to do once every couple of days. I need a new Wifi router.) But I probably won’t make my Wifi router’s power controllable over the Internet. That trick would only work in one direction: once the Internet router is off it’s a lot harder to use the Internet to turn it back on.
(I’ve never been to Stuttgart. I’m told it’s quite nice.)