KFW55 in unheated existing property

Basically, the KFW increased the interest rates significantly again last week.

For new buildings, the conversion of the granary would be a renovation of an existing property.

Hello, thank you for the many responses. I know that I have to submit a building application for the change of use and also that I have to involve an architect, structural engineer, and energy consultant. The preliminary building enquiry is already underway and I have already received a positive verbal commitment. The attic is located within the inner area, has road access, and is surrounded by residential buildings on all sides. KFW 151 only applies if the property is heated, but it is unheated. Therefore, 153 applies here. Quote from the KFW website: "The conversion of unheated non-residential buildings, such as barns, into living space can be financed through the KfW loan." But concerning my actual question: Is it even possible to build only one floor energy-efficiently, or is it absolutely necessary to always renovate or build the entire building energy-efficiently if you only want to use one floor as living space? The whole building or even two floors do not make sense to me, as it is simply too large and correspondingly too expensive.

What you put into the thermal envelope ultimately doesn't matter or is calculated by the energy consultant or they advise you accordingly.

I would calmly check again whether the grain storage ever had an emergency stove somewhere. The KFW does not require that the entire building was heated ;-)
The energy consultant can also help you with this.

Understood. Yes, two rooms on the lower floor were previously used as club rooms. I think there is still a stove in the corner. I will clarify that with the energy consultant. For now, I am waiting for the preliminary decision so that I have it in black and white that I am allowed to convert it into living space, and then I will sit down with the architect and the bank.