Smarthome - I don’t need one ... or do I?

I’d say, 5,000 more for the "normal" electrical work - then I’ll do it,

You have to work out a concept, or get someone who knows about it. "Normal electrical work" and smart home are two completely different things. But I already wrote that further up. Even though there are many manufacturers who keep trying to make something out of what’s already there by selling customers boxes that supposedly turn houses into smart homes. But most of them fail (or rather, don’t even start) with HVAC integration.

What I actually meant to say was maybe you can do smart home parts as self-performed work for the electrical trade (cables, for example)

You can do a lot more yourself. For example, also procure the devices and handle the configuration. So that the electrician basically only has to hook everything up and then commission the system electrically. Of course, you have to find someone who’s willing to cooperate.

already wrote: IT people are biased. But why always use (the well-established systems like) KNX and Loxone instead of a nice open source system (OpenHAB ...) to compare conventional electrical installations and smart homes is beyond my knowledge. The wiring of all smart home systems is similar; a bus system requires somewhat fewer cables than the purely star-shaped wiring we have. But be that as it may. After now 4 months in the mostly self-built and electrified and somewhat smartened house, I can only say: OpenHAB runs great. Slowly a few more playthings are added (various sensors with the option of long-term recordings, smaller programs like lamella rotations of the blinds as desired to, for example, 90°. Naturally after position determination of the blinds (time measurement after fully up or down ;-) and many other things. Especially as an IT person, I advise: Do it yourself. Wiring is easy, programming initially moderately difficult, then always easier. Above all, you know how what works and don’t have to call a system integrator if you want to add, change, or replace something. Of course, bus buttons (KNX/Loxone components) can also be integrated, it’s just not a must. I just wanted to throw that option into the discussion, not to unleash a holy war :p

for IT specialists, it is not an either-or situation. You simply pick the best from everywhere if you can integrate it yourself anyway. If you have to choose only one system that the electrician installs, KNX is simply the most complete.

Instead of using a fine open-source system (OpenHAB ...) for comparison of traditional electrics and smart home, escapes my knowledge.

That is because Openhab is only a small part of the whole. A smart home is not just the top-layer software. It is also the rest that belongs to it. Namely the field level and everything in between.

If you just bring Openhab into the house, it is the same as putting a voice assistant into an unprepared house. It is then more or less usable as a paperweight.

The reality looks like this. Before thinking about the higher levels and automations (Openhab, Homeassistant, home server and other comparable ones), you first have to create the infrastructure that actually wants to be controlled and feed these software platforms with information and data from local sources.

That is why in a smart home, the first thing talked about is wiring, sensors, actuators, etc., and the software framework comes much later, almost last but one. That is why it is more or less pointless to discuss it as long as it is not clear what actually has to be controlled and regulated.

once the other side please, we do not have a smarthome and do not miss it. And since IT people do not like to document, especially not the 3-20 change, it is always a surprise for the family. PS: a way to drive son-in-law away

But why always (the established systems like) KNX and Loxone instead of a fine OpenSource system (OpenHAB ...) for comparing traditional electrical installations and SmartHome is beyond my knowledge.

Well, why Loxone with many electricians? They can quickly plan it through the tool, generate a parts list and order, connect and have it configured automatically. That is very well thought out.