Basement - Is it sensible to have 2 separate underfloor heating circuits in a new building?

In a developer new build (energy efficiency class B, district heating) I have the choice between underfloor heating (basement hallway with one door) over the entire 45 sqm (standard, included anyway, without it is not possible), OR dividing the basement in the middle (then with 2 separate doors), and I could then set the temperature separately. Cost: €3,500.
I want to divide the basement anyway (either now directly or rebuild it myself later with drywall).

In one basement area (20 sqm) is then all the house technology and washer-dryer, photovoltaic storage, etc., and possibly some storage space and also planned some food supplies.
The other basement area/room is intended to be used as an occasional room, a small craft room or workshop, and I generally want that room to be heated.

a)
Does a separately controllable underfloor heating make sense so that I can simply keep the storage room cold, at around 15-18 degrees for example? And then set the other room generally or during use somewhat higher?

Or should I just simply take underfloor heating without a wall, later set up a wall myself and then permanently heat both rooms somewhat? -> Wouldn’t that be a big waste of heat and money, or is that hardly noticeable? Hence the question

b)
I have absolutely no feeling for what costs a 20 sqm basement room that is constantly somewhat heated generates in a year. Are we talking about €100 or €400 or even more? Rough estimate? If I leave the door open, the basement then also heats the ground floor a bit? Or hardly relevant?

c)
Is it even possible to set up a wall (drywall / no load) afterwards on a basement floor with underfloor heating? Or does that cause problems with the screed/fixing/expansion joints/damage to heating pipes etc?

The optional division is shown in the attachment.

In a developer's new build (energy efficiency class B, district heating)

How do you achieve B today in new builds?

1. You can't seriously regulate anything in new builds anyway. There are only small differences in temperatures. In the end, you can at best just unscrew the regulators and let the heating do its job.
2. We can't say what explicit heating will cost you. For that, we'd need to know the district heating prices. But since a new house basically (in reverse) corresponds to a refrigerator or a thermos flask, when you set one room to 15 degrees, you indirectly heat it through the other rooms in the house and might still end up with 18 degrees or more. Where else would the heat go? It shouldn't go through the walls to the outside, so it distributes itself inside the house.
3. You can also install a drywall partition yourself later. It is either glued to the floor or you take an IR thermometer and check where the underfloor heating loops run. Or you can talk to the heating engineer during construction and directly look at the pipe installation. Everything is possible.
4. With my heat pump, heating 20 sqm (if I simply break down the heating costs per sqm) costs about €60 per year. But if I shut off a room, I definitely don’t save that amount (see 2.).

If you ask me, I would have the wall with the door installed now. Unless the budget is already very tight.

As long as you do not take thermal measures in the separation of the basement rooms, it is exactly as describes: the separation will not bring you much practical benefit. I would not have a division of the heating circuits done for €3500. Later you could keep the rooms at the low desired temperature – because cold air tends to stay at the bottom, there is some limited possibility for this. When you then separate the rooms, the thermostat should be in the room that is supposed to stay cooler, and in the sporadically used room that should be warmer, an infrared panel can be installed, which is only switched on when needed. In this way, you have a thermally sensible and cost-effective separation that works better than 2 underfloor heating control circuits.

Let the optional partition wall "Sonderwunsch 01" be installed right away. This way, the space where it is supposed to go is automatically free of heating loops, and the self-installation of this partition wall does not save the world.