Air heat pump or use gas and solar?

What kind of casing?

In the thermal envelope of your building. Or are your basement rooms insulated on the inside against the hallway, for example? Or does your basement have continuous insulation completely on the outside, as well as under the slab?

The basement has perimeter insulation. There is no separate insulation between the rooms. But we had explicitly discussed and also contractually agreed that two specific rooms in the basement are heated and not all of them.

Yes, then all the basement rooms are included in the calculation. It is about the heat loss of the house against the outside temperature. It is the same with us: hallway and hobby room heated, the rest not.

Nevertheless, they marked it incorrectly in the heating load calculation. The rooms simply do not have underfloor heating. Of course, the result of the calculation can still be correct.

Now I hope that tomorrow I get a reasonable energy consultant and they can quickly calculate it for me.

I don't see it that way. But maybe the others can say something about it.