Is Smarthome KNX automation possible based on the floor plan?

Honestly, I thought you had by now well informed yourself about KNX? That you have no clue about some of the most important basics actually makes me suspect the opposite...

Ok, I have informed myself about the basics of automation. Better? Everything works according to fundamental, logical principles. If wind is above x, then raise blinds 1, 2, and 3. If solar radiation is above 300 units and wind is below x, then lower the blinds. Function to determine the sun position based on date and location and then adjust the blind angle accordingly.

I roughly know what exists (window contacts, weather stations, switchable sockets, ...) and that everything can be programmed. I don't know exactly which actuators, sensors, etc. are needed and how it is wired hardware-wise. Software-wise, I could definitely program it myself.

The green bus cable is needed for the complete sensor and actuator system.
Simplified: bus cable to every button (switch), sensor (PM detector, temperature, etc.)
Sockets and other consumers (lamps) are powered by power lines. No green wire is needed there.
The green wires are basically the nervous system, the power lines are the muscles. The two parts are connected through the control cabinet via actuators, etc.

What makes a complete KNX? It depends on what you want from the beginning.
I consider a weather station very important, so I would plan it from the start. A tablet on the wall (visualization) is nice, but absolutely not necessary to rely on immediately.
I see no point in putting smoke detectors on the bus. The only reason would be to get a notification while away if there is smoke. But considering the costs, it’s not worth it to me.

I thought so... so you are still far from: "I have dealt with KNX" but that's okay...

I would lay the green cable everywhere, also to the sockets... why?

Because it practically costs no money... but then the cable is available everywhere. You get really annoyed when you need the cable in some corner and it's not there.

It can also happen that a cable gets damaged during construction and you can't reach the spot afterward... if you have laid it everywhere, you simply go from the other end and supply the room from there... so you lay an open ring for each room and the cable goes to every socket like a string of pearls...

There is no complete KNX... since it is a modular system... meaning you can have many or few devices... both would be complete.

Just make a list of functions you need per room... then we can see further.

Alright, in a first basic version, of course the KNX cable should be present everywhere. Next to every door there is at least one KNX bus coupler. Then there will be 3 venetian blinds in the living room and roller shutters everywhere else. Venetian blinds and roller shutters need wind sensors, measurement of sun intensity (= weather station?) and possibly also a weather forecast for the day?

In my opinion, there should be an away mode that is switched centrally at the entrance. All roller shutters are then set to automatic (venetian blinds open or closed, depending on whether it is the heating or cooling season) and certain sockets are disconnected from the power supply (stove, oven, TV, ...).

In the hallway and staircase we’ll just try it with motion or presence detectors. I still want to install the flush-mounted bus coupler so that switching to manual is still possible later.

It probably makes sense, because of future changes, to make all light sources dimmable? Maybe I want to turn on only half the light in the hallway later, etc...

Expansion stages would then be:
- Window contacts (mainly to indicate at the entrance whether a window is still open when leaving the house – or do window contacts make sense for anything else?)
- Integrate smoke detectors

At the front door I would actually stick to conventional. Mechanical key.

We would probably install a Wolf CWL (300 or 400) and a Rotex HPSU compact. The latter has a cooling function and hygiene water storage. How can this be integrated sensibly or are these devices not suitable? Possibly we would still switch to a geothermal heat pump (model unknown).

Washing machine, dryer and kitchen appliances will all be newly purchased, so that a specific model can be bought here which has bus connection.

One more question, I thought KNX should be laid out in a star topology? Now you’re talking about an open ring per room? Should power be star-shaped and KNX ring-shaped per room?

Wait and see the price your electrician will give you - you'll bury it very quickly.

You are building with [GU], right?