Best retrofit smart home new build

You can also achieve individual room control by measuring the temperature, for example with a touch sensor that is already there anyway, and letting the software take over the regulation. It then controls the valves. That way, you don't have to install ugly thermostats in every room and you won't have them on the wall when you eventually follow the path of proper hydraulic balancing :)

I leave the hydraulic balancing to my heating technician; he gets paid for that.

But I still haven't quite understood what you mean?

He means what everyone else has already written. With a correctly executed and adjusted system, the thermostats are no longer needed. The system regulates itself. In a typical single-family house, this is not a problem since they are usually not palaces.

I leave the hydraulic balancing to my heating engineer, who is paid for it.

Well then, in practice you actually don’t need any control system at all, and certainly no thermostats in the rooms, except for the KfW. Better solution: The actual temperature is detected by the touch sensor (or in motion detectors, etc.), the setpoint temperature is specified in the visualization, the heating actuator does the rest = no ugly thermostat with a dial on the wall and the ERR requirement is fulfilled. Whether you then use this for life or disable the control in the visualization at some point is up to you. Whether something like this works with a DIY smart home from umpteen different manufacturers has to be seen.

You can also achieve individual room control by measuring the temperature, for example, with a touch sensor that is already there and letting the software take over the control. It then controls the valves. This way, you don't have to install ugly thermostats in every room and won't have them on the wall when you eventually follow the path of proper hydraulic balancing :)

Yup, that's exactly how we did it. It works great. The button only shows the ACTUAL temperature. The SETPOINT on the button is set as high as possible. So the valves are always fully open. Thanks to the hydraulic balancing, we have about 22-23 degrees everywhere in the house, and it can’t get warmer because the underfloor heating is designed that way. If we wanted it warmer, we would have to adjust the heating system itself.

Yep, that's exactly how we did it. Works great. The button only shows the ACTUAL temperature. The SETPOINT on the button is set as high as possible. So all valves are always fully open.
Thanks to the hydraulic balancing, we have about 22-23 degrees everywhere in the house and it can't get any warmer because that's how the underfloor heating is designed.
If we wanted it warmer, we would have to adjust the heating itself.

Yeah, maybe you like it that way, but in the bedroom or laundry room I don't need that or want that.
Personally, I feel better if I can adjust the temperature if necessary, even if it doesn’t change from one hour to the next with underfloor heating. I'm aware of that since we also have underfloor heating in our current apartment.

Okay, so let's say smart underfloor heating: pointless.

How about lighting and blinds? I was thinking of actuators like Shelly or Sonoff behind the switches (we’re installing deep boxes all over the house).
That reminds me – ventilation system – does it make sense to make anything smart there?

Yeah, maybe you like that, but I don’t need or want that in the bedroom or laundry room.

In a new house, however, the temperature difference between the living area and the bedroom will not be significant. There are only very few in between, regardless of whether you turn the heating way down in the bedroom.