Can we still slip into a KfW-55 house?

The Kfw55 grant is tied to the 100k€ loan from program 153!

Is your financing already in place? Essentially, the subsidy is not paid out, but the 5k€ is deducted from the 100k€ loan after confirmation by the energy consultant.

Our financing is not yet finalized. Last week we visited our major red house bank. The program 153 was not yet discussed there, as our developer had informed us until now that we would end up at approximately "KfW 60" in terms of value. For the then only remaining 50K loan, the bank offered to handle it themselves. That probably no longer applies in combination with 5000 euros.
So we can still adjust the financing to KFW 55.

Are there any other points that need to be fulfilled besides the technology?
On the KfW page, I do not see that the system air-water heat pump with photovoltaics, underfloor heating, and controlled residential ventilation with heat recovery is sufficient for KfW 55. (See also attachments in #3). There, heat pumps with ground collectors, etc., are more in focus. (Not possible for us due to sandy, dry soil).

It can be worthwhile, but keep in mind that screed and insulation have special requirements.

What, for example, needs to be considered regarding the screed?

Our financing is not yet final. We were at our major red house bank last week. The program 153 has not yet been discussed there, as our developer so far had indicated that we would end up at about "KfW 60" in terms of value. For the only remaining eligible 50K loan, the bank offered to handle it themselves. That probably no longer makes sense in combination with 5000 euros. So we can still adjust the financing to KFW 55.

Are there any other points to meet besides the technology? On the KfW site, I don't see that the system of air-water heat pump with photovoltaics, underfloor heating and controlled residential ventilation with heat recovery is sufficient for KfW 55. (See also attachments in #3). There, heat pumps with ground collectors etc. are rather the focus. (Not possible for us due to sandy, dry soil).

What should be noted for example regarding the screed?

What on earth is KfW 60? There is the Energy Saving Ordinance standard, KfW 55 and lower.

Specifically regarding the screed, there is nothing to note. However, the structure of every surface on the house must be clearly defined.

Is it really a developer? Why do you already have an energy certificate? Is it a type house without individual adjustments that already has an energy certificate? Basically, I would always coordinate with the developer / general contractor on this topic and not undertake anything on your own.

5,000 euros is far too meager to have trouble afterwards if the reference values are not met.

Yes, I had deliberately put KFW 60 in quotation marks. Our developer had set that as the value to represent the current insulation. So to speak, too poor for KFW 55, but already better than exactly KfW 70/Energieeinsparverordnung.

We received the energy certificate at our own request. We wanted to have more precise values regarding the heating planning. We know what we want for the heating system, but we have not yet committed to a company. I have two appointments scheduled for the end of this week.

Overthinking helps little. Ask your developer/energy consultant if they can submit an application for KFW153 and KFW431 for you using the current values and what additional costs this might mean for the construction. The current values should at least theoretically be sufficient (if the individual U-values of masonry, windows, roof, etc. are not exceeded).

The application to KFW is then forwarded to the bank. Ultimately, the application is only reviewed by KFW after it has been signed at the bank. For us, this currently already takes 3 weeks.

Just out of interest: What is your wall construction?