KFW 55 in semi-heated basement - cold basement

Just because of two rooms you don't need a heat pump that's 2kW stronger - this can be stated quite confidently without further values.

What heating load is the house supposed to have? That has to be determined if drilling is based on it... we have 1x140m.

How many sqm of heated area do you have?

We have a heating load of 8.1kW for just under 250 sqm of heated area - and we haven't exaggerated with the insulation (14cm at the top, 10cm cellar).

What is the _exact_ text block for KfW 55?

Fixed price, construction time guarantee, and individual planning:
Each construction project is individually planned in coordination with the future homeowners and adapted to the owners' wishes within the scope of possibilities, structural requirements, and conditions. For the house construction, the builder receives a fixed price guarantee (valid for 12 months) and a construction time guarantee (from 7 months) after defining the scope of services. These provide an outlook on the total expenses for building the house to help you take a secure path to your new home.

Our heating area is 208 sqm without the 2 additional rooms. The heating load has not yet been determined because the execution planning is allegedly not yet completed.

The last post is pure advertising! The previous one about KfW 55 lacks the texts about the requirements for obtaining the Efficiency House status 55. Are you sure you haven't overlooked/forgotten something?

As I have repeatedly found out in the last few days, answers can only help if all information is available.

Rhenish greetings from on the road
Building expert

Then he can't say at all that a bigger heating system is needed.

You will be able to do little to nothing about the additional cost of the underfloor heating - his house construction, his prices.

I would always recommend a full heating system, because otherwise the other rooms without heating have to be heated too.

What are your insulation values?

I have not found anything further. The contract repeatedly states that
Our solid houses are constructed according to the respective valid DIN standards and the recognized rules of building art in a conventional manner. Deviations and changes from this construction and performance description are reserved for the contractor due to legal new regulations, official requirements, changes in case law for technical and static reasons, and by the replacement of building materials of equivalent or higher quality. All dimensions of the drawings and sketches are generally raw dimensions, which must be taken into account during planning, furniture arrangement, etc. The sound and thermal insulation of our properties is carried out in accordance with the requirements of a KfW 55 house according to the Energy Saving Ordinance 2015 and the Renewable Energy Act (Renewable Energy Heat Act) in the version valid at the time of the purchase contract and the applicable sound insulation ordinance.