Does a KFW70 house become a KFW55 house this way?

Hello everyone,

So far we had a house plan that was confirmed in writing by the architect as Kfw70.

However, the following changes have now arisen: geothermal heat pump instead of a gas/solar system, a controlled ventilation system with heat recovery (previously none was planned), 0.5 glazing instead of 0.7 glazing.

Could something like this already have an effect regarding Kfw? Since the architect is currently on vacation for 3 weeks, I can't ask him =(

Best regards

Hello,
everything is possible
We have planned a Kfw 70 house (with geothermal heat pump, controlled residential ventilation + heat recovery, good insulation). Due to the building technology, we could even choose a "simple" glazing - the Uw value for the entire window only needs to be 1.2!!!
We have now also decided on a small photovoltaic system, because with our large family (e.g. constantly running washing machine/dryer/dishwasher) a lot of electricity can be consumed ourselves. This allows us to achieve the values necessary for a KFW 55 house.
An answer for your house can therefore only be given by the person who creates the energy certificate.

KFW55 is possible, but the whole thing must be completely recalculated. We are currently going through the process (from KFW70 to KFW55). As a layperson, I did not know that so many additional forms and things are necessary, all of which must be additionally submitted for KFW55. Above all, the confirmations during the construction phase make it somewhat more complicated. So in general: it is possible that it works out, but it is certainly not guaranteed.

We have now decided on a small photovoltaic system because our large family (constantly running, e.g. washing machine/dryer/dishwasher) can consume a lot of electricity themselves. This allows us to achieve the values required for a KfW 55 house.

Hm, then something is wrong?! Household electricity cannot (NOT at all) be counted in the KfW calculation if there is a separate meter for the heat pump! We also fell for that; KfW or the energy consultant corrected us there. (As mentioned, with 2 separate meters for the heat pump and household, and the photovoltaic system connected to the household, it brings you NOTHING for the KfW calculation - it is explicitly excluded)

Hello Wastl, there will be no separate meters. The heat pump has a direct connection for the electricity from the photovoltaic system, the energy certificate specifies KfW 55. These are the details we have and this is also how the KfW application looks.

Hello Wastl, there will be no separate meters. The heat pump has a direct connection for the electricity from the photovoltaic system, the energy certificate specifies KfW 55. These are the details we have and this is also what the KfW application looks like.

Then it's correct - only the electricity from the photovoltaic system that is used for the heating system (possibly controlled residential ventilation with heat recovery?) qualifies for KfW 55. I just wanted to correct your original post: electricity for the washing machine, dryer, PC, etc. is not eligible for KfW funding. With your setup, you will have to recalculate (pre-calculate) what actually goes into the heat pump and what does not. But the energy planner will have already done that.