ᐅ Control the climate using underfloor heating or through the ventilation system?

No, not really – especially since roof insulation doesn’t actually cost that much. Above all, you shouldn’t base such decisions on just 3-4 responses in a forum...

Add as much thermal mass as possible to the roof – usually, only glass wool is used. That doesn’t really help much with summer heat protection...

@lastdrop

It depends on the unit – there are some with a silent mode. I’m not sure if the same noise limits apply as for the outdoor units of a heating system (but I assume they do).

We had a very good unit from Fujitsu, but when it was over 30°C (86°F), you could still hear it from outside.

In my case, the outdoor unit is installed on the rear extension’s flat roof. There are no issues with the neighbor there.

Just out of curiosity:

When building a new house – would installing such an air conditioning system affect the KfW calculation and possibly the associated funding? An air conditioner can potentially consume a considerable amount of energy.

I’m thinking of the example discussed in this forum about circulation pumps, where it was mentioned that these might cause you to lose your KfW status.

If that is the case, it would be advisable to consult an expert again when planning the installation later on, to avoid risking the approved KfW status and suddenly facing a financing gap.

For houses that are already built and approved, the “changed” KfW value probably no longer matters much. After approval, no one will come by for a second inspection after several years (at least that’s what I assume).

A future buyer would likely be pleased to have a KfW-certified house plus an air conditioning system.

Sebastian79 schrieb:
No, not quite – especially since roof insulation doesn’t really cost much. Above all, you shouldn’t base such decisions on 3-4 replies from a forum...

Put as much mass as possible onto the roof – usually only glass wool is used anyway. That doesn’t really help much with summer heat protection…

@lastdrop

It depends on the device – some have a silent mode. I’m not sure if the same noise limits apply as for the outdoor units of a heating system (but I think they do).

We had a very good unit from Fujitsu, but when it was over 30°C (86°F), you could hear some noise from outside.

In my case, the outdoor unit is placed on the rear extension on the flat roof. There are no issues with the neighbors.

If I understood the architect correctly, he mentioned something about a wooden panel. For this additional insulation measure, a net cost of 2,700 euros was estimated.

I am aware of how to interpret the information from the forum. I see it as a suggestion that I ultimately have to coordinate with the respective craftsman and architect.

The real question is whether the extra roof insulation makes economic sense if the house can be cooled with air conditioning?

Above-rafter insulation is important not only for cooling but also for soundproofing and, of course, thermal insulation. Additionally, you have a waterproof roof underlay – so it’s not that simple.

You won’t be able to cool the house down anyway, because as soon as the devices are turned off, the temperature rises quickly again.

I wouldn’t do without it... I would rather give up the air conditioning.

Mycraft schrieb:
After the first summer, when I could barely or not at all sleep during the few hot weeks, a split air conditioning unit was installed in the bedroom.

I don’t really know what a split unit is, but I guess I want one too.

Sebastian79 schrieb:
We have installed air conditioning or are currently installing it — one unit in the living room, three in the bedrooms and children’s rooms.

So you have an outdoor unit sitting or mounted outside? How does that work exactly?
I googled air conditioning units and found some that are relatively small and mounted on an interior wall. I could live with that in the bedroom.

Saruss schrieb:
I chose not to install one because — personally — I don’t have any issues with a few warmer weeks.

That’s how it is for us too! At least, that’s what I thought, because I also like it a bit cozier. But thanks to the large south-facing window, a lot of sun comes through in summer and heats up the room a lot. We also don’t always keep the roller shutter down. In our old terraced house, we had the whole front wall in the bedroom made of windows — so we were used to the heat. But that heat would also escape through the 78mm (3 inches) insulation ... In our 2014 house, it just stays trapped.

Apart from this thread, I hadn’t really considered an external air conditioning unit, so that’s why I’m asking.

Hopeful regards

ypg schrieb:
So, do you have a unit installed outside, mounted or standing? How should I imagine that?
I looked up air conditioning units: there are devices that are relatively small and installed on an interior wall. That would be something I could live with in the bedroom.

Exactly, one unit is installed outside (somewhere), and one inside the room – that’s what you found when you searched (unfortunately, I’m not allowed to share links here). The outdoor unit is usually only about 70–80 cm (28–31 inches) wide and 20–30 cm (8–12 inches) high.

For just one room, you’re definitely looking at less than 2,000 euros (including installation) if retrofitting.