Air-to-air vs. air-to-water heat pump KFW55 house - cooling function important

Thanks already for the many assessments! That has already given us quite a bit to think about.

What health reasons speak against underfloor cooling?

Raynaud's syndrome (cold in hands or feet = pain). For me this means that I wear cozy socks and thick slippers indoors even in summer. However, our apartment is currently very poorly insulated; in a new building, hopefully, it would not be as bad. Nevertheless, cold feet would be something I would rather avoid.

I think the expectations for the cooling are significantly higher than what it will actually deliver. In the office I often go barefoot (IT people are allowed to do that!) and on the carpet it feels cool but not cold. Uncooled tiles are worse.

I've already written this in some other threads, just briefly: I have cooling via the normal underfloor heating system, controlled by the photovoltaic system. It works great and NO, nobody complains about cold feet. The heat is simply gone. That it’s sufficient for me is surely due to a) the very well insulated house and b) the location at 550m in the pre-Alps - in Cologne on the Rhine it probably wouldn’t be enough. A proper air conditioning system just has much more power and also dehumidifies.

My partner also has no problem walking barefoot on our floors all year round; as mentioned, for me it is health reasons that are disadvantageous. For most people, underfloor heating as cooling certainly wouldn’t be a problem in that regard. By the way, we are building in Bremen.

If you have heat sensitivity, I would definitely put some thought into shading. Don’t forget the issue of light with shading; with proper planning you can shade the sunny sides well and let light in on the other sides.

That is definitely part of the planning; additionally, we want to consider active cooling.

If you always wear slippers anyway, then where is the problem? In case of doubt, just visit such a place. We just had visitors over the weekend and, as always, they were absolutely thrilled with the cooling.

There was just a thread here recently about the fundamental decision between [Luft-Luftwärmepumpe] and [Luft-Wasser-Wärmepumpe].

But what about the humidity with underfloor cooling? When cooling down, the moisture has to go somewhere and will then have to accumulate on walls/on furniture. Currently building a KFW55 with an air-water heat pump and was considering activating the cooling as well once the heating finally arrives. Since a lot of humidity is expected in the new building anyway, I wanted to refrain from that for now and eventually retrofit a proper air conditioning + photovoltaic system when there is some money left over again or loan interest rates are cheaper. I still remember a thread here from a few days ago where they were literally fighting against the humidity.

As already mentioned there, the cooling regulates itself before it reaches a dangerous area. I have not noticed any "fight against moisture" and could not understand it either - especially not with furniture (!).

Retrofit is nonsense. The cooling-capable system differs in control and in the switchable thermostats. Install everything and then tear it out? No way.

I would definitely install a proper air conditioning immediately as well.

Raynaud's syndrome (cold in hands or feet = pain). For me, this means that even in summer I walk around indoors with cozy socks and thick slippers.

Just wondering: what do you think the tiled floor feels like in winter with an air-to-air heat pump? THEN you really have a problem. With underfloor heating, the floor feels warm to the feet. With an air-to-air heat pump, it’s simply cold – of course, it has to be significantly colder since it’s not heated. It has to be at least real wood flooring so that not everyone (not just you) has such cold feet.

Yes, strangely enough, in old buildings etc. a cold floor is very chic and cool all year round - but the floor heating cooled in midsummer is "I imagine it to be terrible" and "I wouldn't want it even if it were given to me." Well, I also imagine the Bugatti Veyron to be impractical for parking, I wouldn't want it even if it were given to me!