Change heating after building application or during construction phase

Hello everyone,

we were approached by our site management to ask whether we should possibly adjust our heating option due to the current events (political, gas, war, etc.).

We are currently building a KfW55 house (city villa, 148sqm) and last year at the time of signing the contract, we had chosen a gas heating system combined with solar thermal. Now we are considering short-term to cancel the gas heating including solar thermal and switch to an air heat pump.

We have a bit of uncertainty about how long the adjustments on the part of the construction company (architect, etc.) will really take. This could possibly lead to a "construction stop" or even a delayed move-in. Regarding the current status of the construction, we are at the point where the foundation slab and the ground floor have been completed and the intermediate ceiling will come next.

To my knowledge, a "supplementary application" must be submitted to the building authority. Nevertheless, further questions arise:

1. Can the heating system still be changed that easily during the construction phase and after receiving the building permit?

2. Which documents are all required for a supplementary application at the building authority? Exterior views, data sheets of the air heat pump, and which others?

3. Could there possibly be problems with the already approved KfW55 application and would a new energy calculation need to be made regarding the funding?

4. Are there any other topics and/or points that should be considered?

Thanks in advance!

Best regards, Martin

So in my building application it even said that I heat with oil (kfw40+), the architect clicked the wrong button.

The main thing is that the energy consultant gives the green light, he just has to recalculate once. Then, as far as I know, it should be fine. Without guarantee

So in my building application it even said that I heat with oil (kfw40+), the architect clicked the wrong option. The main thing is that the energy consultant gives the green light, they just have to recalculate once. Then, as far as I know, it should be fine. Without guarantee

Was the heating adjusted during the construction phase or was only the "selection" wrong in the application?

Also adjusted the heating during the construction phase or was only the "selection" in the application wrong?

Actually changed the manufacturer of the heat pump again during the construction phase. You simply have to meet your energy balance requirements - contact with an energy consultant should help.

Make sure to do it. Even if it leads to delays. You certainly won’t touch the heat transfer surfaces for 50 years. They must be suitable for heat pumps. I also don’t want solar thermal on the roof. It only costs money, makes the heating system unnecessarily complicated, brings little to no benefit, and you will (rather) sooner or later need the space for photovoltaics.

we were approached by our site management,

Exactly, they are your first point of contact for your questions.