ᐅ Air-to-Air vs. Air-to-Water Heat Pump for a KfW55 House – Importance of Cooling Function

Hello everyone,
we are currently deciding between several prefab house suppliers, and a major difference is the heating system offered. Some suppliers install an air-to-air heat pump as standard (cooling available at extra cost), while others provide an air-to-water heat pump with underfloor heating and a ventilation system with heat recovery (an air conditioning unit can be added). Geothermal or groundwater as a heat source will likely not be an option for the plot we are currently considering. It will be a KFW 55 house, initially without photovoltaics for cost reasons, but solar panels are planned to be added later.

We have already read quite a bit on the topic, but as laypeople, we find it difficult to make a decision regarding the heating system. It is important to know that we are very sensitive to heat and want to include active cooling right from the start. In the worst case, we would need to heat/cool only individual rooms.

These are the advantages and disadvantages we know so far:

Heat Pump	Advantages	Disadvantages
Air-to-Air with Cooling Function	Heating and cooling in one system Relatively inexpensive upfront	Noise level still needs to be checked (is it different from a ventilation system noise?) More difficult to control temperatures individually in different rooms compared to underfloor heating
Air-to-Water with Underfloor Heating + Air Conditioning	Switching to other heat sources is easier Air conditioning works very well together with photovoltaics (you want to cool mainly when there is a lot of sunshine) Warm floors in winter	More expensive upfront, especially including the air conditioning (exact cost difference is not clear yet) Air conditioning without photovoltaics means high energy costs
Air-to-Water with Underfloor Heating with Cooling Function	Switching to other heat sources is easier	Only a few degrees of cooling possible Cold floors in summer (a very important disadvantage for health reasons)

In principle, this results in 3 options that we are currently considering (we were advised against underfloor heating with cooling function for the reasons mentioned):

• Install air-to-air heat pump with cooling function
• Install air-to-water with underfloor heating, add air conditioning when photovoltaics are installed, and live with the heat until then
• Install air-to-water with underfloor heating and air conditioning, tolerate high cooling costs until photovoltaics are added

Which option would you prefer, or do you see another solution? Do you have any ideas which option would be better in terms of running costs? Because we probably have a rather expensive plot and need to watch costs during construction, air-to-air currently sounds like the better solution to us.

We would appreciate your assessments.