Determine the consumption of air-to-water heat pump from the total electricity consumption

Which meter do you mean? The extra meter in the distribution box?

Almost 7000kWh for a 150m² KFW40 house sounds like a lot, but it could also include an electric car, sauna, mining farm, and so on.

What unit is MVh?

At the "refrigerator temperatures" (20 degrees) in the KfW40 house, I would have now guessed max 2000 kWh for the heat pump. But where is the remaining 4800 kWh "wasted"? Or just normal household electricity demand and totally messed up hydraulics/floor heating? Hot water temperature possibly at 55...60 degrees? @TE: Your consumptions remain a mystery. We need more input. I recommend starting immediately to note down all meter readings - with correct units - daily until all crystal balls here are polished.

I calculated about 3000 kWh of household electricity with home office. Then you end up with an annual performance factor of ~5 including hot water. That would be really great for an air-to-water heat pump, but it could be the case when I look at the fact that you have already optimized everything. If you really want to know, then have a simple interim meter installed on the Hutschine. Together with the heat quantity meters, this provides the perfect analysis option.

With an assumed 2500-3000 kWh household electricity, you get an annual performance factor of ~2.

I calculated about 3000 kWh household electricity with home office. Then you end up with an annual performance factor of ~5 including hot water.

How did you calculate the annual performance factor?

The readings of the heat quantity meters through the remaining kWh?