Cooling with heat pump via underfloor heating?

And is that really enough? Would you tell me how many rooms or sqm you have upstairs and what kind of air conditioner you have, so that the 'open-door technique' is sufficient?

It might also depend on what standards you have. So we don’t cool the bedrooms down to 18 degrees. We have a Mitsubishi air conditioner, I’m not exactly sure about the exact model, I think SCM 50, with 3 split units SRK 25. 7100 watts cooling capacity in total. Upstairs we have a bathroom, parents’ room, and 3 other rooms. None of them are huge. Currently, we only open the doors to the parents’ room and one child’s room. I like it warm in the bathroom, and the other two rooms are currently used too rarely to keep them cool. For us, the staircase is near the split unit, which has the effect that once the rooms upstairs have cooled down, the hallway downstairs is also noticeably cool. That’s hard to prevent because the cold air naturally wants to go down. ;) But it still distributes sufficiently. We were worried about that at first too. During the planning phase, however, our contact person said that with such a system they cool the entire exhibition rooms and that it has quite a lot of power. We trusted that and see it the same way now. Regarding the note about colds/unpleasantly cold drafts: I also had such problems often when we were somewhere on vacation where it was insanely hot and there was an AC in the room. When you have your own system, you get a feel for it over time. It has proven effective for us not to set the remote control directly to 20°C — even if the effect is of course amazing when you are sweating and then ah step into the cool air. After the initial hype became habit, we now set the device rather to 23 and let the rooms cool down more slowly, plus we cool immediately when we notice it’s getting a bit too warm (usually from 26-27), but then only briefly until it’s comfortable again.

- even though the effect is obviously amazing when you sweat and then - ah - stand in the cool air. After the initial hype became routine, we now set the device to 23 and let the rooms cool down more slowly, also we cool directly when we notice it’s getting a bit too warm (usually from 26-27), but only briefly until it’s comfortable again.

Do you have a different summer than we do? :D I think I can count the days I’ve sweated on one hand. And if it’s 20 degrees outside and 27 inside because of the window areas (greenhouse effect), I would just do a quick airing out for 5 minutes. So basically I follow your argument. And summers will get hotter again with long heat periods. But I can’t relate to your experiences from this year here in Düsseldorf :(

I think the days I have sweated can be counted on one hand.

I can agree for this year, but last year and the year before were drastically different.

Maybe not a different summer but a different house? So it has already gotten quite warm inside here a few times. Although I currently also lack insect screens everywhere for shock ventilation, and I prefer to use photovoltaic power rather than let even a single mosquito into the house. I’m allergic to it, such a bite likes to swell up to the size of a honeydew melon. :D

Shock ventilation only works if there is a bit of wind moving.

We chose the climate less because of summers like this one, but rather because of the summers still to come. Keyword 1.5 degrees in 2030, etc. I was heavily pregnant in August 2019, that was no walk in the park. o_O