Reliability of an energy calculation for KFW55, too high?

Considering that every room in our house has four exterior walls, I find the value very good.

Our house has 7 rooms (+2 hallways).

There are only two rooms that do not have 4 exterior walls (bathroom and children's room), but a hallway and a living room with 5 each.

To me, that sounds like 6 floors with a flat roof. Each room on a different level, except the bathroom and children's room, and the living room at the very top. :D

Oh man... the ratio of surface area to volume doesn't really play an extraordinary role in the consideration.

Optimal would actually be a sphere, or to prevent it from rolling away, say, an igloo. Close to that is the building cube (in modern terms: townhouse).

But for every differently shaped building component, you pay energy on top. The only thing that is probably even less ideal is an L-shaped bungalow, because no rooms share floors and ceilings there at all.

Fortunately, individuality and personal taste still count as well ;)

Meeting the requirements for KfW55 fails more due to transmission heat losses than primary energy demand. For us, a primary energy demand of 45.79 kWh/m²a would have been "allowed" for KfW55, we achieved 25.81 kWh/m²a. That would have easily sufficed for KfW40 (< 33.3 kWh/m²a) as well. The transmission heat loss had to be below 0.266 W/m²K, we achieved 0.246 W/m²K. Here we were still clearly far from KfW40 (< 0.209 W/m²K).

I believe that strongly depends on whether you build massively or not. It was the same for us though. Transmission heat loss was significantly more critical.

We have a transmission heat loss H' T [W/(m²K)] of 0.243. The reference value would be: 0.256. Our energy consultant found serious errors in the thermal insulation verification from the structural engineer hired by the general contractor. And recalculated everything. According to the general contractor's structural engineer, the planned execution should suffice for KFW 55. (He used software that is not even approved by KFW). As a result, the general contractor had to make significant improvements to achieve KFW 55. How fortunate that I hired an external KFW companion and not the structural engineer hired by the general contractor, who would have also created the KFW verification. (That smells like fraud). Improvements had to be made: stronger insulation under the floor slab with even better WLG, stronger insulation under the screed with better WLG, different roller shutters, thicker insulation with better WLG on the attic ceiling..... The same thing I basically did with the TÜV hired by the general contractor. Simply canceled and hired my own construction supervisor.