Control climate with underfloor heating or via the ventilation system?

I tried that once. You get great cold air in the room with the indoor unit. To use it in other rooms, it has to get cold. Then you can’t stand it there anymore. It just doesn’t work! Multisplit or, if the line routes are too long, several small units. Forget about monoblock, even good devices (Siemens in my case) are terribly loud and also provide far too little cooling capacity. Sleeping with a thing like that is not possible.

So if the house is well insulated, you can cool the entire house with one ceiling cassette... you don't need multiple indoor units, but you can install some...

However you do it, both variants have advantages and disadvantages...

The operating and acquisition costs are similarly high for both variants...

For this, all doors must be open, nothing works individually anymore. In addition, the unit must have the appropriate cooling capacity - so rather a commercial area.

I would still not suspect the whole house, but rather one floor.

If you could conveniently and comfortably control the temperature on a floor from one location, you would not install radiators/underfloor heating in every room, but only in the hallway.

For that, all doors must be open, nothing works individually anymore. In addition, the unit must then have an appropriate cooling capacity - so rather in the commercial sector.

I would still rather not suspect the whole house, but one floor.

As I have found out, about 3500 watts per floor are sufficient in a standard house... so nothing commercial... also the doors do not have to be open... I think you are installing a controlled residential ventilation system, where the air is distributed anyway, since there are overflow zones or openings.

And you yourself keep writing that with a heater, larger temperature differences from room to room are hardly possible... now practically the same applies if you cool the house...

We are talking here about an air cooling system with the worst heat transfer medium - and a controlled residential ventilation system has heat recovery, which initially ruins the effect. You are therefore wrong - otherwise, in commercial areas, one could save countless cooling systems and install only one unit.