Is HAR/technology sufficiently dimensioned? Any experiences?

Hello everyone,

we are currently planning our house and have now received a draft. We are currently wondering whether the technical room is too small. I have attached a drawing.
The 12.44 sqm apparently also includes the space under the stairs. Of course, it can be used to store items that are rarely needed, but will our technology fit in the room?
If I haven't forgotten anything, the following should be accommodated there:

[*]Air heat pump including cooling (no air conditioner, split unit)
[*]Ventilation system
[*]Energy storage (Sonnen battery)
[*]Inverter for the photovoltaic system
[*]Underfloor heating (for 200 sqm)
[*]Electricity cabinet (2 very large cabinets due to smart home)
[*]Connections (water, electricity, fiber optic, ...)
[*]Optional a small server cabinet

I think it will not fit, but I also find it very difficult to estimate. Maybe the space under the stairs can be used, or you could use the space above the underfloor heating and install the electricity cabinets there, or the energy storage and inverter. But I don't know if that is possible and allowed.
What is your assessment? If it doesn’t fit, by how much should I enlarge the room so that it fits?

Best regards

P.S. Water treatment system

It is best if you draw everything in with the manufacturer's measurements.

The main electrical connection can be hung over the water
Our fuse box is 1.4 m high, so there is not much space above or below

For 12 sqm, the entire staircase must have been included, although at least 50% has no standing height
I would not count that part

What kind of device is the underfloor heating supposed to be?

What kind of device is the underfloor heating supposed to be?

I think he means the control unit

If he means the heating circuit distributor by FHZ. It does not belong there, but in the middle of the house, so that the distances to the rooms are roughly the same.

Yes, I was mistaken about the FHZ. I just had our apartment in mind and we have a regulation there. In a house, you always have one per floor and preferably centrally located.

I have now picked out a few manufacturers and roughly marked the data. It should work, but I think you can’t just rely on the dimensions from the manufacturer. For the battery and the inverter, I know that you don’t need more space than the devices themselves take up. Only one cable goes in. It’s similar with the electrical boxes. Here, just a few more cables come in. But air-to-water heat pump, ventilation, water, etc. How much space do you need here for the installation and the pipes, etc?