Lighting and electrical planning in new construction

The 20 K should be sufficient for a good standard. However, the problem will be that you have to spend at least another 20 K to be prepared for a (central) retrofit, because that really means significantly more supply lines to all sockets/outlets (in addition to the pure bus line), which electricians generally charge well for. Then, of course, all sensors/actuators come on top, which can quickly amount to 10 - 15 K. In addition, one must not forget that KNX wiring without KNX components is not very usable or later requires considerable effort for rewiring.

You misunderstood me. I don’t want to do standard and have [KNX] prepared at the same time. It’s more about the minimal installation of [KNX], but without the frills (visualization, scenes, door contacts, etc...) that can possibly be retrofitted later.

It is just as much a luxury as a suitable kitchen or a bathroom exactly according to your own ideas and not just functional from the landlord.

die man dann zusammen mt dem Elektro-Betrieb über die nächsten Jahre immer weiter aufbauen kann.

That will rather not happen if you cannot do the work yourself. You will spend at least twice as much instead of saving.

und später auch Heizung und Lüftung darüber steuern können.

You should have that done right away if it is even necessary. Because that will also cost more later than during construction.

Visualsierung brauche ich erstmal nicht.

That is correct. You hardly ever need visualization. Houses without modern electronics don’t have it either. Basically, it is a pure nice-to-have. And that again is a point you can very well build up yourself over the years, and here you can save money because no professional company has to assign someone for several days and sell you the hardware to place your pictures and buttons on a screen.

Furthermore, it can also be quickly tinkered with free software on the phone in the initial period.

Szenen kann man später ergänzen.

Scenes are built and changed anyway all the time. Habits and needs change.

Sind 20.000€ überhaupt realistisch

Yes, that is doable. At least you get the usual standard equipment of a general contractor with KNX implemented for that. So the well-known ceiling connection point with switching etc. Just ask the company from Alt-Karow, they are capable. However, I cannot say anything about the prices.

Türkontakte etc...

These are also hard to retrofit. At least if you want it pretty (invisible), functional and cheap. So I would make a plan about what is really essential in a KNX installation and definitely have that done. The rest can then be built or retrofitted yourself if necessary.

Door contacts are rather not possible. Visualization, on the other hand, is.

Ah, okay, but that doesn't change anything, because for basic KNX and later upgrades you have to have all the cables in from the start. Likewise, things like window contacts are not so easy to retrofit nicely, so you might as well install (and use) them right away. I think for a house of that size, budgeting around 50 K for KNX "good" (including network) is about right. From that you might be able to deduct maybe 5, at most 10 K for the advanced features, but not more.

Ah, okay, but that doesn't change anything,

Hehe, I like the statement :)... Reads well... a la: It's okay like that... but of course it doesn't change anything!!! :) :) :) P.S. yes, I'm in on that too. Although I think that with 20K you can do something, you just have to find the right partner and possibly add another 5K or so. Better to do a bit less garden work in the first year and then gradually.

Ah, okay, but that doesn't change anything, because for basic KNX and later upgrades you have to have all the cables in from the start. Likewise, things like window contacts are not so easy to retrofit nicely, so you should install (and use) them right away. I think for a house in the size range, budgeting around 50 K for KNX "well" (including network) is about right. From that you might be able to subtract maybe 5, at most 10 K for the advanced features, but not more.

These are very different assessments regarding the price. I would be willing to add another 10k on top of the calculated sum, but unfortunately 50k is no longer enough. Due to the rising costs of raw materials, the money is simply needed as a contingency reserve for overruns.

From your point of view, what is necessary/useful to have done during construction? What can you do without? What can be retrofitted? Do I need window and door contacts?