How can the utility room in the basement be effectively integrated into the thermal envelope?

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apply the flat rate of 1.0 for a new building ???

sorry, that is nonsense, it is intended for old buildings where thermal bridges can no longer be optimized.
Both flat rates, including the optimized one, have nothing to do with a new building. In this case, energy consultants can hardly calculate thermal bridges or have never looked into Annex 2.
The KfW even refers to the excessive costs that arise in this way. See the KfW FAQ.
I was even asked this question once in an exam for an old building, where I had 2 unheated garages included.

As an energy consultant, there is little you can do about outdated architecture. I know why I am both,...

I'm so glad that our architect is also an energy consultant.
Seems like a good combination ...

Everything else would already be strange because of the €4,000 subsidy from the KfW,...

As far as I am correctly informed:

- The thermal envelope is not to be equated with the building's outer shell; one can differentiate here between, for example, heated and unheated rooms. Otherwise, how else could one adequately insulate the garage in the basement? I would not want to know the U-value of a 5m garage door, or try to "compensate" with thicker exterior walls on the ground floor.

- In a KFW document, it is stated that doors to unheated areas (e.g., basement) must meet the same requirements as doors to the outside.

For my case, I once roughly calculated the U-value of the entire building. With additional insulation under the screed of the ground floor and an appropriate door to the basement, I would achieve an overall U-value of 0.207, which would be sufficient for Kfw 40.

Have I calculated this correctly? Individual U-values weighted according to the total area of the thermal envelope? Thermal bridges are, of course, not taken into account....