I started off with some zwave devices and lately added Wi-Fi + MQTT.
My first observation is that zwave devices are more expensive (e.g. the cost of typical light switch is ~60 CAD$ for zwave vs ~20 CAD$ for Wi-Fi based)
I’m curious to know what are the advantages / disadvantages for using zwave rather than e.g. Wi-Fi (ESP8266)?
How do they differ in power consumption, range, reliability etc.?
Does OpenHAB have better support for one of them?
Thanks
For me the example of the light switch is the most pertinent one:
zwave offers to use existing light switches and add automation seamlessly (providing your electrical installation support this); a benefit that outweighs much in my case
ESP8266 are cheap and nice, but they are hacky and typically cannot be integrated with existing light switches; hence they only function if OH is up, your wifi works, etc…
Whipping out my cell and launching the app to switch lights on and off is for me good for emergencies only, it needs to seamlessly integrate … for people at home, visitors, etc
Right now, I am in a rental space in a country where electrical installation are …interesting…and hence cannot use zwave; but for the reasons above, I am only using things that have at the very least a native app as a fallback (in case my work at OH2 results in a problem 
or it crashes, etc and renders it useless for some time); hue lights and tp-link’s are my friends
Not answering your questions, but power consumption is marginal, they all seem to be reliable (although esp solutions are often DIY…), etc…and for me the reasons above are way more important
The reason I don’t go for most WiFi connected devices is that they are reliant on some cloud service for operation.
Not true at all. I know at least four brands for wifi based infrastructure (esp or cc chip) that offer the integration in an existing electrical installation (inputs for the switches/push buttons and relay outputs).
No, there is no problem if openHAB is down! The manual operation is there!
Take a look at mongooseOS!
Please don’t spread misleading information!
Even though it might be the case for a cloud service providing some services, there is no actual need for those if you hack the device (of course, for some devices physical intervention on the device is necessary)!
Cool, thanks much for making me aware of that. Live and learn…it is a fast developing environment. Apologies, I did not intent ill will and wish I had learned about them earlier.
I am not a fan of either of them, I still do trust copper/fiber for transmission!
I only have experience with ZWave, and only in the US. When made my decision to go with ZWave the wifi device market was not as diverse as it is now.
At the time I went with ZWave because I knew I could get it to work with a minimum of extra work. At the time and even now, a lot of the commercal wifi devices require depending on cloud services or replacing the firmware on the device. I’m sure that isn’t true for all of them but it is true for the ones I know about.
Aesthetically, I needed others that looked like regular others and light switches that took up no more space in the box than any other switch, and would look like and match my existing dark brown switches. A lot of the wifi switches look really cool and all but I want my HA to blend in and match my existing don’t dumb switches. This actually limited me to one switch from one brand (Linear for the curious) which has ZWave switches with swap out able rocket buttons so I could get the dark brown. There was nothing wifi that meet this requirement at the time.
Another consideration is how congested your WiFi already is. If you have a lot of devices you may want to run a separate wifi AP on a different channel for your HA devices. Maybe even a separate LAN.
Security wise I think it is mostly the same with ZWave maybe having a slight edge only because it is not as big a target as WiFi is.
Finally, make sure to also consider Zigbee in your consideration. While still more expensive than wifi devices, I see lots that are cheaper than ZWave and new vendors entering into the HA market (e.g. Ikea) seem to be coming that standard.
Hacking WiFi devices isn’t always possible. Most ESP8266-based devices probably can be - witness the plethora of Sonoff information out there. But unless someone has already figured out how to hack your particular device, and you yourself have some elite hacking skills you’re out of luck.
Z-Wave devices by their nature require local control. I’m not saying that Z-Wave devices are perfect, but at least you don’t have to modify them to achieve local control.
This is indeed the biggest problem with wifi devices! More than the congestion itself is the neighboring wifi emitters (channels, power settings, etc.)
I have worked with both: Z-wave and wifi! I think there is always the application and the surrounding environment that determines the technology chosen!
As for my own home setup (not that anybody asked): always wired! 
In ZWave, you can also directly associate switches and sensors to actuators (other than the one with the switch attached) such as say a motion sensor to a light. That sort of operation will still work if openHAB or your WiFi is down, including group switching to e.g. operate all of your lights or roller shutters in a room in one go, or to have a (portable) remote to allow for (interactive) dimming. ZWave is also using less power, that’s an advantage for battery operated devices such as sensors.
ZWave has a better range because of the frequency it’s using, plus it’s a mesh network (nodes can forward messages to distant nodes). Now while you can create a meshed WiFi network, too, there’s quite some drawbacks in doing so.
On a more abstract level, ZWave has some advantages w.r.t. security and cluttering/congestion of the 2.4 GHz band.
Not sure which WiFi switches you’re referring to @20 CAN$ (Sonoff ?), but that’s about the cheapest ones you can get, and I’m pretty sure that at least those don’t provide the same set of features and electrical safety as the zwave devices @ 60 CAN$ ~= 40EUR that you’re comparing them to. Think of capability to do fading, measurements, scenery switching etc.
For 45-50€, you can get either a zwave dimmer, quad channel LED dimmer, or a dual channel switch over here in EU.
It is obvious we can not talk about comparing battery capable devices of the two protocols! Definitely Z-wave is a winner if you talk about battery powered devices (in terms of autonomy)!
This is a huge problem with many Z-wave devices! It was a very good idea taken from the broadcast supporting protocols from the 80’s/90’s but with no homogeneous implementation (i.e. producers having different command classes)
I would like to repeat myself: I don’t support any of the two solutions in terms of reliability, or consistency, but I would like people to still see the objective parts of both of them!
A “which is better” question will always draw a lot of different views, and there’s no one answer really, but it’s an interesting debate .
That’s not strictly correct in most cases. This is exactly the purpose of the BASIC command class - to provide a basic level of compatibility.
This is really one of Z-Waves strengths (“this” being compatibility / inter-operability). the command classes that define a devices functions are well defined and in general devices from one supplier will operate nicely with another suppliers devices. This give a huge range of devices to choose from, from hundreds of manufacturers and devices are tested for this compatibility (although that doesn’t provide 100% guarantee of compliance, but it’s close!).
I’ve not worked with the WiFi devices, but I’ve worked a lot with BLE, Z-Wave and ZigBee, and IMHO none of these (currently) provide this level of compatibility between devices from different suppliers that Z-Wave affords (although ZigBee isn’t too bad, and maybe one day BLE will get there, but it’s still a ways off).
I’m not very knowledgeable in the WiFi device market, so I don’t want to say what they can’t do 'cause I don’t really know , but Z-Wave and also ZigBee are backed by large groups with many companies - you pay a bit more for this but you know these companies will be around in the years to come.
Thank you all for this article. I just purchased z-wave for my place and as I was reading this wondering if I made the right decisions. I live in an apartment where Wifi space is a premium here. When I look at available networks I get over 30 devices listed. Based on what I read, I made a good choice.
Wired is great when you can do it. Unfortunately more often than not wired is unfeasible to impossible.
It can’t be a too “huge” a problem!
I have never had any issues with direct associations, and I use it quite often. Sure there are some devices that doesn’t do exactly everything you could wish for, but the basics has never failed me. And I have a lot of different manufacturers.
Wired is of course always very good, especially if you are building a new house, but perhaps not as flexible.
WiFi would not work in my house, since my basement is concrete, and also I have chimney in the center of the house, WiFi always has problems here because of this. Sure, maybe I can solve it by putting two-three access points on each floor, but that wouldn’t make sense to me. Also missing battery devices (I don’t like them in zwave, but sometimes they are unavoidable). I am pretty sure WiFi devices uses more idle power than Z-Wave devices.
I don’t “love” Z-Wave, but I find it the best all in all for me. There are a lot of devices, most of them are CE marked, if not all, and they are easy to install.
This is anyway the nicest thing with OH, that you can mix systems, and what fits a specific site, budget and technical interest in hacking. 