160m2 would require a 8kW heatpump. If the home has poor building fabric insulation you would require one 1.5 times bigger. Similar applies, if you live further north where the outside temp is colder, requiring the system to work harder if not sized correctly,
As a rule of thumb you are looking at a heatpump somewhere between 9 to 11kW which would be capable of running the house.
However, I can’t stress enough how important it is to do a proper heat loss calculation, which will not only be more accurate but also calculate the internal temperature required against the outside temp in your area and the average number of heating days per year and come up with an accurate size for your requirements/needs, as an heatpump too small for the house will cause it to work harder and fail prematurely. A system that is too large will cause the system to cycle.
For what its worth a 5kW system would be suitable for the averaged sized 3 bed house, upto 100sqm.