Integrate cooling into controlled residential ventilation or have air conditioning separate?

Sure, good insulation is important but it does not replace an air conditioner.
It is not just about temperature but also about dehumidification.
Both factors determine how the temperature in the room is perceived.
I would no longer want to do without an air conditioner in the bedroom.

How big is the place? And how many unshaded south and roof windows will there be?

If all windows have exterior shading, you can roughly estimate cooling about 400 sqm to at least "freezing cold" with 13 kW in a new build.

I cool 140 sqm of an old building here, open up to the roof, huge window front on the south (shaded by the roof) with 3.5 kW. That’s enough even for the 2018 summer in southern Germany so that my wife throws the blanket over herself in the evening.

So the offer is at least twice as high. Both in terms of price and performance. It will definitely be enough to cool the upper floor. If the staircase is open, enough cold air falls down. I would even go so far as to say it would be enough to cool the upper hallway with just one unit. Ideally at the highest point of the house. Then it’s only important to turn on the system early and run it (at then low power). That way the air has enough time to mix.

If you are often away and only turn on the system when it’s already 28 degrees inside, that no longer works. Then you need several end devices in the important rooms.

If you want more opinions on this, [kaelte-treffpunkt] would be a good place. But beware – the guys there are not as delicate as here in the forum...

No matter what you decide, avoid skylights as much as possible. Those things are the devil. Even roller shutters don’t help, at least not dark ones – the air gap between the window and the shutter gets boiling hot and then heats the room. Better a ventilated shading! And maybe prefer red over anthracite for the roof tiles. That will probably bring 1-2° as well. Whether you absolutely need an air conditioner also depends on the regional climate. In the humid conditions of southern Germany, where the air stands still for days, I wouldn’t want to do without one either, but here it usually cools down quite a bit at night, there is always some wind, and the humidity is generally lower, so with the right ventilation technique (with sufficient shading, not like here in the apartment ) you can manage well without one. How it is for you, you have to judge. But if you do need one, save yourself the gimmicks about controlled residential ventilation and get a real air conditioner.

You also don’t write anything about your roof construction! Maybe it’s not even necessary? Here, everyone probably assumes 1.5 stories with a gable roof!

Above the upper floor we have a 22cm concrete ceiling, on top of that a 24cm insulation lying on it, and a cold roof as a gable roof in stone gray (light gray). So I don’t worry about the heating up of the roof or the rooms below.

the geothermal heat exchanger is also available for the small Zehnder. The 30m piping costs extra of course and is not cheap (it is installed by the shell builder in our case). The piping in the ground costs approximately €2200 net. The alternative would be a brine heat exchanger, which is another €2000 more expensive.

For that, you could already build yourself an air conditioning system.

The Comfocool rather provides dehumidification and 1 degree less in the house, and you can run the system fully during the day. That can noticeably improve the indoor climate. For thermal protection, shading is more important for south-facing windows. For the price of the Comfocool, you can certainly get 1-3 split air conditioning units, which of course have a completely different cooling capacity. So Comfocool would be nice, but probably too expensive.

We also had some heat problems in the new building this year, mainly because my self-programmed roller shutter control was not running well yet, shading was still missing in the extension, the ventilation system was unregulated (full at noon, solved with a software update and time control), and due to missing outdoor facilities (no trees for shade, gravel).

Next year I want to install a central split air conditioning unit, mainly to dehumidify if needed in summer.

Oh, one more thing: The Comfocool only works with the powerful controlled residential ventilation Q600, the air volumes of the normal ones in single-family houses Q350 and Q450 are not sufficient.