Is KFW300 possible without QNG seal?

Can you give a bit more details regarding your solid construction with KFN40

I can tell you how it is for me:

42.5cm Ytong 0.07W/mK Basement 24cm reinforced concrete + 18cm insulation Floor slab 25cm reinforced concrete on 18cm insulation Roof: 240mm insulation between rafters + 100mm wood fiber above roof insulation

Arge Haus creates EH40 even with unfilled 36.5 stones. With a thick photovoltaic system, battery storage, ventilation system, I believe it is not that difficult to make an EH55 house into an EH40 house, right? Windows and doors are already at a very high standard anyway.

For KfW 40, not only is a low energy demand required (=large photovoltaic system with storage), but the heat loss itself is also limited. Our general contractor also said they built a KFW40 house with 36 cm Ytong. Depending on the shape and basement, however, this is only possible with the 42 cm. Here, however, some (~30 - 60 pieces) thermal bridges must also be explicitly calculated.

Here, however, some (~30 - 60) thermal bridges must be explicitly calculated.

However, the calculation does not change the house itself. It only changes on paper. Costs money, brings no advantage - since there is no funding without additional QNG.

QNG is not a funding condition for KFW300. QNG is a requirement for increased funding (+50k€ compared to without QNG) And yes, the bridge calculation itself does not change anything about the house, but it is necessary to prove that it is a KFW40 house. If all bridges are calculated and still too much heat is lost inside, something must be changed in the house. Don't get me wrong, I have no idea why KFW40 should not be calculated with simplified reference values like KFW55 (i.e. u-value wall < x, u-value roof < x), this is a waste of money without end (~100€ per thermal bridge). At least the values that must be used without explicit calculation should be lowered, since every thermal bridge that is calculated reduces the value.

QNG is not a funding requirement for KFW300.

QNG Plus is the minimum requirement for the 300. Not the formal certificate, but compliance with the conditions stated there regarding emissions. In this respect, you have to at least partially comply with QNG and proof must be provided. It is somewhat cheaper than with a certificate (after all, everyone wants to make money :rolleyes: ) That is why I only stayed with 55, but renovated better – insulated wall U-value up to 0.11W/(m²K).