Ventilation, heating, cooling – Which solution is future-proof for Bien-Zenker?

Dear forum,

we are facing some decisions regarding our planned prefabricated house project with the company Bien-Zenker.

Under "Building Services > Insulation" we have already asked a question about insulation. Next, we are concerned with the topic of heating/climate/ventilation.

As standard, Bien-Zenker offers the Proxon comfort air conditioning system. Here and in other forums, one reads opposing opinions. My opinion is that in terms of heating, an air-water heat pump with underfloor heating promises more comfortable warmth and probably requires less electricity for heating, since the Proxon only uses the heat pump with heat recovery and otherwise has to heat via direct electric auxiliary heaters in the air outlets. What is the current sentiment in the forum on this?

As air-water heat pump, the company offers an integral device (Stiebel Eltron) with an internal heat pump. What is your opinion here, also regarding the efficiency of an internal heat pump?

Matching the currently hot summer, I am concerned with the topic of cooling. The Proxon can cool as standard and apparently also dehumidify? Regarding the latter, I read that this only occurs via ventilation (passive?). The underfloor heating could also cool, advertised with only 2-4 degrees, the Proxon as far as I know with 6-8, but this does not dehumidify the room – with all disadvantages (perceived stuffiness, potential mold growth, etc.). Considering that a house ventilation system is installed even with the underfloor heating, I wonder, however, to what extent this dehumidification should be worse than that of the Proxon? To be on the safe side, we are considering whether the installation or at least the pre-installation of an air conditioning system should be planned? Question: For a house with the above-mentioned insulation class and appropriate shading – currently with a preference for blinds – can a house even heat up so much, e.g. 25/26+ degrees, that an air conditioning system is really necessary?

Can an air conditioning system be operated in conjunction with the existing ventilation system, since this already has the piping etc. throughout the house? If not, then probably only split units remain in the corresponding rooms? Can these be installed flush-mounted? If we only want to retrofit these later, is it worth planning e.g. with corresponding pipes in the walls? Otherwise, I am worried about the vapor diffusion control foil if holes in the exterior wall become necessary later. Is this justified?

Thank you very much!

Question: In a house with the above-mentioned insulation class and appropriate shading - currently preferably venetian blinds - can a house still heat up that much, e.g. 25/26+ degrees,

No problem. But it takes longer. Conversely: Once it is warm inside, it is difficult to get the heat out again. Important: plan for summer heat protection

An air-to-air heat pump.....
We have a Schwörerhaus.

Conclusion: Install that only as a ventilation system and additionally an air-to-water heat pump.

Reasons: the floor remains cold, retrofitting underfloor heating is expensive.
Disadvantages when selling the house.
I wouldn’t call it an air conditioning system.... 800 watts cooling capacity = too little for a house.
Heating capacity of air-to-air is just enough for autumn.....
In winter, the additional heating is expensive, as it runs directly on electricity.

Advantages: clean in a KfW 55 house, in summer I turn the unit off or only run it weekly (due to pests, etc.)
Hot water comes from the domestic hot water heat pump, which uses less than 50 kWh per month (summer) in our case.

We have come to terms with it... and are glad to have a fireplace as well.
That reduces the electricity consumption for the heat pump to 2500-3000 kWh per year.

Without it would be around 5-6000 kWh.

(This is just my opinion)