Temperature in the heating room (air source heat pump)

Hello, up to what temperatures can it drop in the winter in the heating room? I have not found any information about the ambient temperature at which the indoor unit of my future air heat pump (16 kW) can be operated. It is a half-timbered house with 60 cm sandstone walls on the ground floor. The floor level of the heating room is about 30 cm below ground due to the slope. The house is currently being completely renovated. The question arises whether I should leave the heating room completely uninsulated (apart from the walls and ceiling to the heated rooms), coat the heating room with insulating plaster (the heated rooms on the ground floor will receive 8 cm insulating plaster), or even plan a heating circuit for the heating room. The room is about 25 sqm in size. Are there any experiences with the temperature in the heating room when operating an air heat pump? Thank you very much for your input! Egon

My entire heat pump is even located outdoors = Monoblock. The indoor unit in the split system does not care about the temperature at all. Whether it is efficient to operate the hot water storage there at 5 degrees is another question.

However, I would also try to keep the room as warm as possible, as long as it can be done with reasonable effort.

Will also have a 200 liter hot water tank. The heat output of the indoor unit is therefore negligible, so it could become uncomfortably cool without a heating circuit? The washing machine should also be located in the room.

It doesn't harm the washing machine if you only have 10 degrees room temperature. It just needs to be frost-free, everything else is a bonus