The annual assessment is, in my opinion, irrelevant for the sizing of the heat pump.
We have approximately 190 sqm of heated area and a building volume of just over 1000 cubic meters. According to the heating load calculation, the 55 Arotherm would have been sufficient, except for the pump capacity. That is why we are now getting the 75, which is actually too large.
When I see 120 sqm, I assert that the minimum factor 2 is oversized.
The energy consultant does NOT do this. For the sizing, you need a TGA planner.