Which smart home system is suitable for our new building?

If I may raise a question: Would it make sense to control the access points via regular LAN cables, then connect them to a power outlet that goes directly to a KNX binary actuator in the basement? Then, for example, one could safely turn the (Unifi) access points on and off at certain times (if you don't want the WLAN radiation) and wouldn't need to use Unifi software (Access Point Controller). Apparently, it doesn't really work to make Unifi access points radiation-free via the controller (I believe there are special scripts for this...). Am I seeing this correctly?

I find this thread a bit amusing.

I have the feeling that the OP is asking questions about things he heard somewhere and also uses technical terms that he might roughly understand, but in my opinion, the network and IT knowledge seems rather rudimentary. And the many suggestions and possibilities only confuse the OP even more and lead to even more questions.

Just the last 3 pages about POE switch behind the TV. I have understood it as him wanting to power only the switch itself with POE from the technical room to avoid occupying an additional socket behind the TV with the switch, and the devices connected to the switch only need the data connection but do not require POE themselves. Yes, such switches exist, for example from Ubiquiti and are called UniFi Flex-Mini.

Regarding KNX and home automation, unfortunately, I cannot contribute because as an IT professional I deal with it every day at work, but at home honestly I am not interested in it anymore. When the doorbell rings, I go to the door and open it to see who is there. If the postman is at the door and I am not home, he should just leave the package with the neighbors. I will see it when I am home again. And I control my lights and shutters in the classic way, by moving to the switch and pressing it if needed. I still do not miss anything at home :)

can you explain to me in detail what you would recommend, also with regard to power consumption?

No, because I don't know what you want to do and also not how many buttons you want to press before having the TV, receiver, etc. "in operation."

I only advise, just calculate it.

A 24 port switch can easily draw 30 watts. 260 kWh per year... not insignificant...

A 24-port switch can also easily draw 30 watts. 260 kWh per year... not insignificant...

Now I have connected a power meter to my 24-port switch (Zyxel GS1900 - smartmanaged). It currently takes 7 watts with only a few active ports. The specifications found in the datasheets are usually the maximum consumption.

you understood me about the switches and access points

Should I do it like this or just connect access points and switches to power in the rooms?

I will distribute 12 LAN ports in the house
I would need either a 12-port PoE switch or an 8-port normal and a 5-port PoE

Do the LAN ports on the PoE switch always consume power even when they are not in use?

Now I have connected a power meter to my 24-port switch (Zyxel GS1900 - smart managed). It currently uses 7 watts with only a few active ports. The specifications you find in the datasheets are usually the maximum consumption.

Oh, that’s good. My Cisco 350 24 unfortunately uses 45W. That is more than the NAS and server.