Definition of outer shell in connection with promotion

Hello,

since this is my first post, a brief introduction: My family and I want to return to our home country next year after a longer stay abroad. There is quite a lot of vacancy there, and we have already started looking for a house. We don't yet know exactly what it will end up being; that depends entirely on what opportunities come our way. Of course, this raises many questions, so let's get started:

There is a funding program here for the "reuse of vacant buildings as residential space." In it, it says:

"at least 50 percent of the
building envelope, excluding earth-contacting
components, must be maintained
and no significant
change in the building's volume may occur"

My questions: What exactly does that mean? What is meant by building envelope? The entire wall? Only the facade? What are earth-contacting parts?

I have already contacted the office that coordinates the funding about this. They told me that for more precise definitions, I should consult a building planner (which I will need anyway when submitting the funding application). But I just want to understand it beforehand.

Does anyone have expertise in this matter?

Many thanks in advance for your professional advice.
Regards

That would probably refer to the facade and roof, which are to be preserved, similar to monument protection. Energetic changes are also possible from the inside, namely on the exterior wall (from the inside). It may also concern the appearance of the windows. Parts in contact with the ground would, in my understanding, be the floor slab or basement plinth.

But I don’t really know, it’s just an assumption.

Brief regards

"At least 50 percent of the
building envelope, excluding earth-contacting
components, must be preserved and there must be no significant
change to the building’s volume"

A value of at least 50% of the substance to be preserved means that the result must still be predominantly "old," so that you do not receive funding just for preserving a facade while otherwise constructing an entirely new building.

The floor area and basement walls make up a large part; including them would make the threshold too easy to meet – something visible that impacts the cityscape or landscape is also supposed to be preserved. Therefore, the percentage figure practically and purposefully refers to the above-ground parts of the house.

Kubatur (volume) is the outer shape in terms of basic forms (cube, cuboid, pyramid, sphere, cone, ...). Changing a mansard roof to a flat roof would be a very significant alteration, whereas extending dormers from ventilation openings to residential windows would be insignificant, as the basic shape of the roof would remain. Extensions on the courtyard side are usually seen more leniently, and such areas can be used for the adjustable nearly 50%.

I do not see any statement regarding the application of insulation materials derived from the wording. The volume is not changed by plastering a sandstone wall in the future. In the case of listed buildings (note: this does not necessarily refer to the individual object; there is also so-called ensemble protection, frequently applied in old towns or Gründerzeit factory housing estates!), such matters may of course have to be observed in addition to these funding conditions, but I do not read this from the funding conditions themselves. Kubatur means, as said, the basic form, not the fine detailing of facade appearance, window profiles, and so forth.

P.S.: a dispute or discretionary case could be whether one is allowed to replace a damaged roof covering with shingles or with "Mönch und Nonne" tiles in "Frankfurter Pfanne" style. It would be a change in substance, not a change in volume, and thus more of a monument protection aspect.