Small Bungalow Floor Plan - Optimization Potential?

I also thought of the long side 11m facing the street, about 8m into the property, then you have a great garden feeling and enjoy looking at your house. If you plan solid construction, think about the octameter, I would take 36cm filled bricks, plastered inside and outside, done. The upper windows are cleaned twice a year from a ladder, still by ourselves.

I would have also thought that it is better to have a large roof surface facing south since I have to install a photovoltaic system (Baden-Württemberg).

Our orientation of the photovoltaic system is east/west, south is overrated. In winter, not much sun comes anyway, and in summer the sun is almost vertical, for east/west from 6 am to 8 pm.

KNN - look here:

OK. That's what you mean by KNN. Then your desired house is out. The program is basically for social housing (and also requires various confirmations, which are complex/expensive). You could do it if you plan completely differently. Between 71 and 85 sqm of living space you need, for example, four "individual rooms", i.e. living or retreat rooms (commonly understood: 4x living room/bedroom/dining room/children's room or similar) each with at least 10 sqm. So besides your living room and bedroom you must have two more rooms. A study and a dining room - so the large living room divided into three rooms. Social housing. P.S. A kitchen or eat-in kitchen is NOT an individual room.

For me it is questionable whether the combination of solid construction and KfW 40 (or even tighter) is then directly out regarding cost efficiency?

No (by the way, all houses are equally airtight, just differently insulated), they are not. Whether thermal insulation is now 14 cm or 16 cm thick makes only a few € difference in material price, for example.

With wood it is - expressed layman-like - one more panel in between or the plastic bag.

Yes, that is simpler.

many thanks for the clarification - thus KNN is definitely out and not worth another thought.

unfortunately my post simply disappeared again yesterday,

This is absolutely incomprehensible to me, I could not and still cannot find any reason for it.

@11ant You had already commented on my post yesterday - many thanks for that. Unfortunately, I could only skim your reply before everything was gone.

In my notary's safe, it is still in perfect condition, see below. However, I can also quote my paragraphs from it here again in a citable form:
This is a delight, you did that exemplary. The relevant height difference of your property is about one meter or about 80 cm within the house foundation area. Placing the house parallel to the contour line was a smart choice. According to the 11ant basement rule (see external: "With or without basement: a rule as a decision-making tool") a basement or the equally expensive measures when "foregoing" it cost you about 40% of the basement price on the cost item "caused by the property". [ / ]
You can find how to determine the more suitable construction method at the source of the aforementioned basement rule under "Services" (keyword switching). EH55 is no longer KfW subsidized because it has largely been caught up by the legal standard GEG2024. You don't need to meet more than that, but it is also not worthwhile. Save yourself the lowering of the roof, build a gable roof with 38° pitch and install the technology in the attic, then you can significantly reduce it on the ground floor and then only have the house entries in the HAR/utility room.
You will find a bungalow builder (albeit with a multi-person household) most suitable to you here in

But your suggestion to keep the roof pitch at 38 degrees and place the technology in the attic stuck with me. Then there would be more space in the utility room on the ground floor or you could even make it smaller.
Would you then have to reinforce/insulate the ceiling more? (Noise of the technology) Or would that also have an effect on the insulation of the roof?

I don't see any special measures as necessary here, I would take the attic anyway within the thermal envelope. did it like this here:

[...] we already discussed the topic of the "heating room" in the attic with @Golfi90 [...]

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Thank you for posting your answer again. From Golfi90's post history, I gather that where the hot water tank is located in the roof above, there should be a bathtub on the ground floor below. Is that correct? Or was that an inside joke?