Which smart home system is suitable for our new building?

I already understand your concept, but it doesn’t give me the possibility to switch every socket the way I want. Even with 5x1.5 I can only switch 3 groups per circuit.

Apparently not. It’s not about what you want or don’t want. That’s just not how it’s done. The sockets are placed in the distribution box and switched from there via actuators. Doing something like that with KNX flush-mounted actuators is a completely unnecessary material battle. A few cables to the distribution box are definitely much cheaper than 45 actuators and their connections. Such a thing is usually only for cases when something was forgotten and then rather via RF.

Yes, the problem is not specifically with KNX but with presence detectors (which are mostly used with KNX) Does anyone of you have dogs and KNX?? Would you say that KNX is at all useful with dogs (especially for light control)? I imagine it can be annoying if the dog constantly triggers the light. But I can’t really judge since I have never lived in a KNX house with a dog.

Oh, that’s exhausting. It has NOTHING to do with KNX and detectors exist in almost every automation system! Nothing nothing nothing nothing has anything to do with KNX! That happens to you in DIY smart homes from the hardware store just the same and yes, also with radio o_O

Obviously not. It's not about whether you want something or not. You just don't do it that way. You put the sockets into the distribution box and switch them from there using an actuator. Doing something like this with KNX flush-mounted actuators is a completely unnecessary material extravaganza. A few cables to the distribution box are definitely much cheaper than 45 actuators and their connection. This is normally only done if you've forgotten something and then only via RF.

I would need 15x 5x1.5 to the distribution box to switch all sockets individually. Although no, that applies to bus cables. In reality, there are 45 positions with almost 80 sockets. So about 25 5x1.5 to the distribution box.

Let's leave it at that. You have your idea, it doesn't align with mine, that's okay. And I'm not a layperson either ;)

Just calculate it for yourself, then the idea is different. Fortunately, we don’t want to talk about the meaningfulness. 80 switching points in a larger single-family house are not uncommon either. Four 20-channel switching actuators and the job is done.

What would a KNX installation in the budget version look like?

Exactly what you are planning there. I don’t find 20K particularly expensive when you consider that nowadays even a click-clack installation in a single-family house doesn’t come in under 15K (yes, I know the general contractor still only credits about ~5K if removed).

Regarding your other questions, what does "all" mean to you? I don’t know your house. Are all 5 or all 25 control points?

With underfloor heating it’s not so critical nowadays. The actuators are usually supplied by the heating engineer, so you’ve already paid for them anyway. So you only need 2 actuators, and you can calculate what they cost. You need the touch sensors anyway for the other tasks.

That the batch of window contacts is discontinued is of course annoying. Here I would try to at least properly integrate the terrace door and front door during construction. The rest can then be retrofitted later as needed with EnOcean.

-For power outlets, you can later use flush-mounted KNX RF or other wireless power outlets (probably don’t need many anyway) (we want to retrofit some power outlets that are outside the standard ourselves anyway)

That is exactly what you should not do because here you end up spending double or triple. This exact approach makes KNX installations extremely expensive.

Note: The more you plan and implement at the beginning, the cheaper it will be in the end.

But of course all this is hypothetical considerations. Because nothing concrete can be presented here.

here is our floor plan

I will talk to our electrician again regarding the KNX budget version to see what price he offers.
The electrician mainly emphasized the star wiring because that is the most complex part of the smart home and it involves a lot of work and is expensive for him (probably no desire to do it)

If it becomes too expensive, we will stick with wireless for DIY installation

as you already said, you basically only build once in a lifetime but eventually, the money runs out

I have one more question about access points.
Is one POE access point per floor enough for us?

Unfortunately, we have to use WALL access points. Ceiling installation was not possible according to the builder (supposedly due to structural reasons)
We plan to hide the WALL access point behind the TV on each floor (we don’t like it visually on the upper wall)
There is always a LAN cable behind the TV anyway

If I were to use premium everywhere in the house, I wouldn't have a 5, but an 8 in front.

Certainly, but you wrongly think that KNX is reserved only for the premium segment. That is actually one of the great advantages of KNX, that you can set it up however you want/can (financially and functionally). Only a few things are absolutely necessary in every installation. From there, the price curve steadily decreases, unless you particularly want golden touch sensors (yes, those do exist).

But yes, you can definitely bring KNX into the house with relatively little money. You just need a partner who knows their stuff and knows more about KNX than what he/she learned in training, especially if it is not supposed to become conventionally 1:1 to KNX as usual.

Certainly, upwards there are no limits.

And in the end, the nicest thing is what you tinkered together yourself anyway...

Perfect with KNX. That’s exactly why I chose it for my house back then. There is hardly any other system that gives so much leeway to the resident/owner.