Building according to the Energy Saving Ordinance 2016 or KfW55

The advantage for us is that you don't have to wrap the house in plastic foil and also don't need a ventilation system.

Uh - will your place then be drafty or how should I understand that? The house is just as airtight as with ETICS (which by the way doesn't have to be plastic, there are plenty of alternatives) and needs to be ventilated just the same. Monolithic or ETICS - that has no influence on ventilation.

Most general contractors ensure energy efficiency through external insulation of the facade. This includes a vapor-tight membrane. To prevent excessive humidity inside the house, this is usually combined with a central ventilation system. The ventilation system itself is also more efficient when ventilating, as the energy does not completely escape through the window.

For us, this was not an option. I do not want an airtight house (indoor climate) nor external insulation on the facade. I think this solution can be applied to old buildings, but if I am building new, I choose the masonry so that the brick has sufficient insulating properties. We decided on a Poroton T8 brick with a wall thickness of 42.5 cm. Of course, this is a matter of price and only comes into consideration if you are building solid.

But as I already said, the KFW subsidy covers almost all the additional costs, and the better building fabric is then your "profit."

By the way: I am not generally against a ventilation system. If it is financially feasible, it can certainly be done additionally. I would just make sure that the ventilation system is not required for the KfW55 standards.

Just my 2 Cents.

Here Energy Saving Ordinance 2016 without ventilation, the house has an airtight envelope but everything without foil, and of course had to pass the blower door test.

Basement solid construction with Poroton brick T12 36cm,

Ground floor + attic completely wooden house with approx. 34.8-38.8cm exterior walls U-value 0.13-0.15 W/m²K
+ exterior plaster
+ 6cm wood fiberboard
+ 6/20 and 6/24 duo louvered timber studs with 20-24cm blown-in insulation
+ 1.5cm OSB
+ 6cm installation layer with wood fiber insulation board
+ 1.5cm OSB (joints glued with airtight tape = airtight envelope)
+ 1.3cm drywall
+ painter’s fleece + interior paint

Roof overall with
+ tiles
+ 3cm battens
+ 3cm counter battens
+ 1.6cm diffusion-open wood fiberboard
+ 8/24cm solid structural timber rafters with 24cm blown-in insulation
+ 1.2cm OSB board, joints glued
+ 3cm battens
+ 1.3cm drywall

The temperatures were absolutely comfortable during the first hot weeks. Maximum room temperature in the attic around 24°C with 35°C outside.
Air-water heat pump then of course only produces hot water.

Here temperature comparison weather station on the roof outside, and on the same day in the ground floor living area. It had already been hot for a few days. At night just always ventilate well.

This includes a vapor-impermeable foil.

Well, I may have slept through the building construction lectures, but since when are foils installed in walls?

This includes a vapor-tight foil.

I have never heard that such a foil is installed in ETICS. Nonsense.

I don't want an airtight house

Then why are you building one? If KfW 55, then Blower Door Test. And it must be just as good as for every KfW 55 house. So your house will be just as airtight.

To prevent humidity inside the house from getting too high, this is usually combined with a central ventilation system.

Since we just established that your house is airtight as well, I would be interested to know what you do against the high humidity.

Better building fabric is then your "gain".

Better building fabric compared to ETICS?
By the way, my house is also becoming KfW 55. I am also getting ETICS, but as usual without foil. Stone, resol, plaster.

Here the Energy Saving Ordinance 2016 without ventilation, the house has an airtight envelope but all without foil, and of course had to pass the blower door test.

I keep hearing that. There was no blower door test for our house.