this is my first post and I’m just starting to learn about OpenHAB. So please excuse any misguided questions.
I’m currently building a house and shortly have to decide on the electrical wiring and home automation system. What do I want to do in the house later:
Control lights (pre-set scenarios including: on, off, dimming)
Automate/control heating and cooling via a heat pump
Automate/control blinds and awnings
Access the intercom
Alarm system and window sensors
Potentially control other things like music, lawn mowers etc.
Now, I’ve learned from reading some posts here that the best way to go about it is to install the hardware and professional system controls that run independently and then use OpenHAB as an overarching control system. As the electrician is set by the building developer, I have to go with what he’s capable to deliver. I was offered either a KNX or a Loxone system. Naturally, I prefer open standards and protocols but am a bit apprehensive about the supposed very high cost of KNX systems and the difficulty of programming them.
My questions basically revolve around the hardware setup, where I don’t have all the concepts fully clear. Let’s assume I choose a KNX setup.
What hardware do I need and what can be replaced by OpenHAB? Bus system, cable wiring…
More specifically, do I need a full KNX setup first incl. a home server (e.g., Gira X1) or would this server be replaced by my OpenHAB server?
I’ve seen that Loxone provides its own proprietary mini-server and in the bus they also have further devices (my understanding is that they’re SPS). I’ve seen that pre-programmed SPS are also on the market for KNX. What would be the use case and potentially advantages of using those?
Again, sorry if those questions are very basic but I couldn’t quite figure them out after reading about the topic for a while.
For knx with openHAB you will need of course the knx bus with power supply, the knx actuators and sensors and wall switches. Furthermore you will need a device to connect to knx. An easy and cheap way would be a knx/IP Gateway, about 130EUR. If using more than one bus line, I would prefer a knx/IP Router, much more expensive… about 350EUR, but much better configurable.
There is no need for a home server at all, as this is exactly the job openHAB will deal with.
In question of a SPS such as Siemens Logo! or similar, you can use this to do advanced functionality without openHAB. But as you want to use openHAB, there is no need for such things, all automation can be done in openHAB. Of course you may want to split some low level functions to work even if openHAB has stopped to work, so this would be done in such devices.
knx is an international standard and there are more than 400 manufacturers which provide knx hardware. knx is available since the late 1990s, so it’s a really old industry standard, it’s used in professional environment such as hotels, manufacturer locations, hospitals, but more and more even in “better” private homes.
Loxone is cheaper but there is much less hardware to chose from.
I strongly recommend an ETS licence (argh… 1000EUR, but you can get it cheaper when purchasing in groups)
Great, this is very helpful. Thank you very much for your detailed response!
Would still have to discuss how many bus lines I will need. But seems like there are tutorials how to set up the knx IP router in case I need to.
Regarding the SPS devices, I would not be worried so much if automated functions stop working if my openHAB server is down. However, I would always want to be able to operate the heating via thermostats and to turn on some lights in such cases. Is that what you mean with some low level functions?
I do have a strong preference for knx over loxone. However, apart from the price the advantage with Loxone could be that I would get a fully running system before I start tinkering with openHAB for the first time. And my wife wouldn’t appreciate it too much if we’re moving in and the lights don’t work for the first few weeks.
Lastly, I would be interested to understand exactly why you recommend an ETS license. My understanding is that I can set up the system only by using openHAB. Or do I first need to configure sensors and actuators within ETS before I start working with openHAB? It just seems that I wouldn’t need ETS once the system is running so it was one of the first items I was hoping to save money on.
ETS (Engineering Tool Software) is the Software to configure knx. There is no option to configure knx without ETS. This part of configuration is done by your electrician, but if you want to change something, you will need your electrician over and over again. With ETS you will save this money
Heating/Cooling is a standard job in knx, you will need a thermostat (integrated in wall switch) and a knx actuator which is controlled by the thermostat. What I meant with low level is more like “if light in bathroom is switched on, start ventilation after 20 Seconds. If Light in Bathroom is switched off, stop Ventilation dependent on runtime of Light”, this can’t be done without some logic, which may not be implemented in all actuators or switches.
If you’re fine with losing the “smart” part if openHAB is down, there is no need for SPS devices, as openHAB is capable to do all the “smart” stuff.
Thanks again for the in-depth response. That’s again very helpful! And sorry for the late reply, but I wanted to first read up a little more before posting again.
I’m still not completely sure I understand the difference between standard knx functionality and what openHAB would add on top. Let’s assume I would have a wall switch to control the light. My understanding would be that with the standard bus I could program a specific on/off variation that controls one or several actuators (let’s say two separate lights in the room). Now, with openHAB I could add
Other scenarios (first, switch on the same lights, second click, dimm lights, third click dimm lights and shut blinds etc.)
A smart logic that changes the actuator response depending on some inputs (sensors, time of day) as you were describing it
For ETS it seems that I’ve just missed the last collective purchase at the knx-forum. Will need to wait for that to get a better a deal it seems.
I’ve looked at some components now and it seems that MDT would offer good value for money. So, I’m asking my electrician to consider them over the standard Gira. Still putting together the individual elements of the final system.
Standard functionality of knx is very dependent of your hardware There are thousands of knx devices out there, each with individual “standard” functionality…
But as a minimum I would say, take a look at a conventional wiring.
You can get some Lamps, which are switched ON
and OFF through a (one) wall switch.
and OFF through more than one wall switch (typically 2 switches, but even more are possible).
and OFF through wall push buttons and a Relay.
through wall push buttons and a Relay. The light will went out after a couple of Minutes.
You can get a thermostat to automatically switch on and off the heating and cooling.
You can get switches to control your roller shutters.
All these things will work with a minimum knx hardware (of course you will need individual hardware for each of these issues)
There are some tasks which are possible in a conventional wiring with some effort, for example move the jalousie to upper position if wind is to strong. This is very easy for knx, as every shutter actuator has some logic for this functionality, so the only thing you will need in addition is a knx wind gauge
Even more complex logic would be possible through a SPS or some logic modules, but these modules are expensive and it’s complex to configure it.
openHAB (or similar home automation systems) will do exactly this logic part, and more, openHAB will grant access not only to knx but to much more than 100 normally not interoperable systems, including (raw) data from internet.
If you want to visualize all the switches in your home, openHAB offers you a variety of UIs to use. For this part you would definitely need additional hardware when using knx only.
openHAB will get every change of a switch, light or whatever is connected to or controlled by knx, openHAB will be able to control all things connected to knx, so it would be very easy to realize your points 1 and 2
