Is insulating the exterior wall sensible or not?

I don't know what this has to do with the original topic‍♂, but the house is in Vorarlberg... I think it's better to end this here because everything is being discussed except the actual concern. It was worth a try. Thanks for the very interesting discussion

Don't you think it would have been important (and fair) to provide this crucial information right at the beginning, or at the latest after the first reference to the German Building Energy Act? Then the further responses would probably have been different.

everything is being discussed except the actual concern. It was worth a try. Thanks for the very interesting discussion

And maybe next time respond more kindly to complete strangers who wanted to help you. Snappy sentences ending with exclamation marks don't necessarily invite further engagement with your question.

But asking if I have ever read a newspaper or watched TV. I had asked very kindly. And maybe next time respond more kindly to complete strangers who want help. It really is a great forum. It wasn’t even worth the attempt. Have a nice day

Standing air is a very good insulator.. If moisture gets into the rock wool through any leak, you will have problems that you might only notice late. I would do it without. Best regards

It can be done easily. That’s all I wanted to know. Thanks Steffi33

Standing air is a very good insulator..

The only question is how to keep the air from moving in an open façade ;) . With a wooden battens, the wind keeps blowing along the house wall – the insulating effect is nonexistent. It’s just for the appearance.
You basically have standing air in typical insulation materials – enclosed (even if they are foamed with other gases).

If moisture gets into the mineral wool through some leakage,

In the solution the OP is considering (with mineral wool), it’s not a matter of if, but only whether it will mold this winter or only in spring. For that, you choose a different construction method.

I would make the substructure stronger and insulate at least 10cm, for example. Above that, a membrane that repels water but allows vapor to pass through. The first centimeters of insulation have the most impact. After that, it becomes relatively cheaper because many costs are incurred anyway.