Calculation of KFW40+ criteria - Update

Dear house construction forum,

I would like to hear your feedback: we are currently discussing the KFW40+ calculation with our energy consultant. According to the energy consultant, the calculation parameters have changed as of 08/10 by the ministry (update), which means that our construction project in its current execution no longer meets the requirements. In the current situation at the construction site, this approach by the ministry is hardly understandable to me. Are you aware of this issue? And if so, is there any indication whether this will remain?

I would like to hear your feedback: we are currently in discussion with our energy consultant about the KFW40+ calculation. According to the energy consultant, the calculation parameters from the ministry changed as of 08/10 (update), which means our construction project in its current execution no longer meets the requirements. Given the current situation at the construction site, this approach by the ministry is hardly comprehensible to me. Are you aware of this problem? And if so, is there any indication whether this will remain?

The criteria are probably being continuously adjusted (= tightened)... For us, it was like that in mid-July right in the middle of the process. We then had to send the first draft because the previous values still applied to it due to the creation date of the first calculation. Based on these values, approval is then also granted - at least that’s how our energy consultant explained it to us. For us, it was about a KfW40 project for the "small component" without QNG.

According to the energy consultant, something had also changed in July during our calculation, even for the better. Previously, due to the planned air conditioning, we still had to install a photovoltaic storage system to ensure enough “green electricity” was available, but this was no longer necessary in the further calculation, and the photovoltaic system itself was allowed to be smaller (although it probably won't be). In our case, however, it was not directly related to the KfW40 standard, but purely relevant for the LCA calculation.

We have now received information from our energy consultant that our photovoltaic system needs to almost triple and the storage capacity needs to double. Our (finished) house provider will cover the costs, but we are still wondering how such a major change comes about. Do I need to worry about the insulation of the house?

For us, the photovoltaic system had nothing to do with the insulation, but was only necessary for the LCA. It's about the fact that the ecological balance is worse with grid electricity than with self-generated electricity. For example, if you use very many energy-intensive building materials (brick, concrete, styrofoam, etc.), they lower the ecological balance. However, this is offset if you generate more electricity yourself over the building's lifetime, because that is ecologically better than the electricity mix from the grid. What materials are you building with ?

Thank you for the quick response, it will be a prefabricated wooden house.