Window offers like day and night

Please write in the details about what was so catastrophic.

Dr Hix has already provided a pretty fitting list.

Additionally: sealing tape with thick OUTSIDE printed on it was used on the inside and it was said that this was the right way, and the connection strip in the kitchen was installed at the top of the window because of a higher worktop (this was corrected).

Support blocks were either completely forgotten or just cut off from a random loose roof batten (spruce/pine)

I thought the roof batten under our terrace door was a unique piece.

As cute as I find the candle test (I can fully relate to it from the bottom of my heart!), it was still useless. Air tightness is not about the wind possibly blowing through here (the outer compression tape should already prevent that), but about no warm room air being allowed to penetrate the construction at this point.

Hehe thanks. So if it is mainly about that, then everything is fine.

Problem:
A 10cm insulation must still be added to the exterior of the mentioned building in order to comply with the energy saving ordinance. For this, the window reveal must also be insulated – 5cm on the left and right sides are to be added. This means the windows would be 10cm narrower. However, the windows are already quite small and light is a scarce commodity in the building.
We would like to prevent losing even more light by making the windows even smaller. Is it conceivable to first enlarge and cut out the window reveal and then install the insulation? Or are there perhaps particularly narrow insulating materials? Any tips?

Making it wider is not possible, otherwise the lintel will not sit properly. Reveals insulation or reveal panels is the keyword. In the reveals, just take 3cm Resol or Bauder panels, they have WLG 025.

In addition, insulation is applied on the frame, and 3cm fits well there. Even with 5cm insulation, it is only 2cm narrower on each side.

But in existing buildings, there is no obligation to insulate the facade, unless it was not a residential building.

Our windows were set further out. A frame was installed and the windows were placed in it.

A 10cm insulation still has to be added to the outside of the mentioned building in order to comply with the Energy Saving Ordinance

Is that really the case? In existing buildings, the obligation to carry out "changed" components according to the Energy Saving Ordinance does not apply, provided that the building as a whole ultimately exceeds the permissible reference values by no more than 40%. (Energy Saving Ordinance §9 para. 1) This means that you theoretically have the option to achieve the corresponding values through other adjustments. Often, a detailed thermal bridge calculation is a suitable approach here. It only costs a fraction of the facade insulation and can quite well produce the same result on paper.

But even if that is not sufficient, the question arises whether the entire facade actually needs to be insulated. The "10% rule" (e.g. when repairing plaster) always refers to the specific component. So if the entire north side receives new plaster and thus more than 10% of all plaster surfaces on the building are affected overall, the obligation to insulate applies only to the north facade.

Another option would be an exemption according to §25, which is usually relatively easy to justify, especially considering the facade and its exorbitant costs.

I would find it a pity if the charm of an old industrial building were disfigured by an ETICS.