Window offers like day and night

We might want to achieve a change of use, and the structural engineering will also be completely reapplied for. I'm afraid we won't get by with existing use rights. But whether everything actually needs to be insulated is the question. A specialist needs to calculate that. Good tip! We probably won't manage to preserve the industrial facade, even if we would like to. The facade is severely damaged; simple repairs are no longer sufficient. We are considering plastering everything and at least preserving the window arches. Let's see.

I’m afraid we won’t get through with grandfathering.

What else should the repurposed building be in the end, if not an old building? To impose a new building and its requirements would be ridiculous, and to my knowledge, there is no third classification for residential buildings.

I had previously assumed that for a conversion and change of use, e.g., into living space, the current [Energieeinsparverordnung] must be complied with? Is that not the case?

The Energy Saving Ordinance is basically intended for new buildings but also contains regulations for alterations to existing buildings. The intention is clear; no one should be forced to tear up their existing residential building unnecessarily, but at least for measures already planned, it should be ensured that they at least come close to the requirements for new buildings.

The Energy Saving Ordinance therefore only distinguishes between houses that are newly built and those that already exist but are "altered." The change of use is nothing other than an "alteration" in this sense. And in that case, what I wrote above applies:

The place must comply with the values of the reference building + 40% - that's it.

Problem: A 10cm insulation still needs to be added to the outside of the mentioned building in order to comply with the energy saving regulations. For this, the window reveal would also need to be insulated -

That all sounds very much like concrete measures - what is so urgent about them before the usage concept is even established?

Mmh, this is hair-pulling. Our consultant is not willing to look for alternatives so that the windows don't become so much narrower. He just wants to take away 10 cm. We have the impression that he is the wrong person for us - he does more new construction. We need an expert for old building renovation, especially regarding the Energy Saving Ordinance. Where can you find such a person?

The windows are "bricked up" from the outside with clinker. There is only a 1 cm window frame there. Sawing off this brick cladding would be madness - utopian - not possible. Insulating from the inside would be possible, but should hardly have any effects regarding the Energy Saving Ordinance, since the cold is already inside the wall.

It really remains only a as narrow as possible and therefore highly effective reveal insulation and slightly smaller windows, as we see it. We are now checking whether 3 cm on the left and right is enough with high-quality insulating materials. If anyone has material suggestions, gladly send them. First, we are looking at the Resol and Bauder plates mentioned by and scouring the internet.

Apart from that, the window offer from provider 2 was not as cheap as we thought after all. He forgot a few items. We have now demanded these. Let's see what comes out of it then.

That all sounds very much like concrete measures - what of that is urgent before the usage concept is even in place?

The owner wants to carry out measures by the end of March so that he can claim them on his taxes.