Is preparing for an air conditioner worth it?

Does anyone know how long the KfW is allowed to check/sanction the subsidized energy certificate?

In my opinion, it is 10 years. So for the lifespan in a normal house, it is still possible to officially retrofit at some point without any concerns.

Zubi123 is right. Evidence: "Information and diligence obligations of the grant recipient Within 10 years after the confirmation of the application, the following documents must be kept by the grant recipient and presented to KFW upon request..." (Quote p. 11 information sheet on application BEG residential building grant 461 Efficiency House) "Furthermore, KfW is entitled to check compliance with the funding conditions on site at the grant recipient (...) The audit rights of KfW apply for 10 years from the date of application confirmation/commitment." (p. 2, General Terms and Conditions for the Application and Awarding of Grant Products of KfW via the KfW Grant Portal)

Zubi123 is right. Evidence: "Information and diligence obligations of the grant recipient Within 10 years after application confirmation, the following documents must be kept by the grant recipient and presented to KfW upon request..." (Quote p. 11 information sheet for BEG residential building grant application 461 Efficiency House) "Furthermore, KfW is entitled to check compliance with the funding conditions on site at the grant recipient (...) The audit rights of KfW apply for 10 years from the date of application confirmation/commitment." (p. 2, General Terms and Conditions for the Application and Award of Grant Products of KfW via the KfW grant portal)

Are there any experiences in the community about this, or are these empty "threats" from KfW?

With all the preparations, I am skeptical. Whenever something has been prepared, fireplace, ventilation, etc., it has later not been carried out.

So you believe that without a recalculation by an energy consultant, we cannot install an air conditioner without losing the KFW status?

We have a semi-detached house from the developer and we are not allowed to install a range hood either because otherwise the KFW status will be lost, according to the developer.

They do not do a recalculation by the energy consultant.

Why should an air conditioning system worsen the energy efficiency of a building? They are promoted by [Bafa] because they IMPROVE the energy efficiency of buildings.