Energy consultant recommends KFW 55 - Recommended with solid construction?

We had planned KfW 70, with air-water heat pump and controlled residential ventilation we almost achieved a perfect landing at KfW 55. Slightly thicker perimeter insulation was necessary. The wall construction is brick.

We had planned KfW 70, with an air-to-water heat pump and controlled residential ventilation we almost hit a perfect score at KfW 55. Slightly thicker perimeter insulation was necessary. The wall structure is brick.

May I ask what wall thickness you have?

36.5 cm

There is also the trick where the main contractor hires their own structural engineer who calculates the building envelope "incorrectly"... for example, including the attic even though the top floor ceiling is the thermal envelope...

My colleague built with Ytong 36.5cm (U-value 0.23) and achieved KFW55 (originally planned was KFW70). A controlled residential ventilation system and an air-to-water heat pump were installed as building services.

Thermal bridge optimization was done, but nothing was manipulated here. The contractor specializes in the Ytong construction method and has a consistent concept that he adheres to. (Different materials with different U-values, etc., etc.).

I do not see any problems with the existing building services/insulation at first. I would question more closely what the cause is.

There is also the trick where the general contractor hires their own structural engineer who "incorrectly" calculates the building envelope... e.g. counts the attic even though the top floor ceiling is the thermal envelope...

Trick = subsidy fraud?