New Construction KfW 55 EE: Different opinions between energy consultant and general contractor

Important for a builder is always HT', because this value shows how good the building envelope is and thus automatically how large the heating load of a building is. And possibly to bother the energy consultant about the thermal bridge certificate, because the thermal bridge surcharge goes directly into HT' and is often only estimated in advance and revised afterwards. And if, as here, there is almost no buffer available, a KFW55EE can also be canceled afterwards with the confirmation.

One should also keep in mind that politics prescribe certain values in the calculations. Since heat pumps failed until the penultimate Energy Saving Ordinance, the primary energy factor was simply set to 0 here, which does not represent the current electricity mix. Furthermore, as soon as a photovoltaic system is added, an infinitely large battery is tacitly assumed, i.e. possibly 100% autonomy. Even if no battery appears in the system technology and 25% is a more realistic autonomy value without storage.

The relatively poor exterior walls have to be compensated for somehow, as their area is simply too large. Often, only the roof and the windows remain, hence the dream values :) The question for me would rather be about the thermal bridge verification, or rather, what kind of thermal bridge surcharge was applied at all.

The thermal bridges are specified in the application for the KfW as a flat rate of 0.05 W/(m2K). Regarding the exterior walls, this is probably also why the energy consultant’s adjustment from aerated concrete 009 to 008 was made?!

Yes, 36.5 cm walls are currently more in line with the Building Energy Act, BEG is closer to 42.5 cm. You can see yourself, the better value still remains above 0.20 U-value. The thermal bridge surcharge must be proven by the energy consultant, even if they take the worse one of 0.05. Either via an equivalence proof, which depends on whether the planning colleague adhered to DIN 4108 Beiblatt 2, or an individual proof, in all other cases the thermal bridge surcharge is otherwise higher and your H't fails, and with it the KfW55EE.

Ah sorry, not clearly formulated. Funding from KfW.

Then I actually don't see any question, build as submitted.

The contract with the general contractor has not yet been signed. There were still a few issues regarding the construction service description to clarify, but the KfW application had to be submitted beforehand.

Well then, good luck with the price negotiation.

Just as an example. I have about a U-value of 0.13 with 20cm mineral wool wlg 032 on my wall in solid construction with a 2cm air layer