Surcharge KfW 55 and geothermal energy with deep drilling

Hello,

we want to avoid using Styrofoam in our house. Multipor would probably allow for a more robust facade without Styrofoam, but our builder has no experience with it and would already charge an extra >5,000€ for mineral wool.

The house is 1.5 stories high and offers 160 sqm. The builder uses 24 cm aerated concrete and 12 cm ETICS as standard. For 36.5 cm aerated concrete, we would get 3,100€ reimbursed and thus meet the Energy Saving Ordinance 2016. For KfW 55, according to the builder, a 48 cm aerated concrete with lambda 0.08 and thicker insulation of the base slab would be necessary. This results in an extra cost of about 12,000€.

Is the difference between KfW 70/Energy Saving Ordinance 2016 and KfW 55 really that significant? According to the Ytong flyer, KfW 55 should be possible with a 42.5 cm block with lambda 0.08.

We have a similar issue with the heat pump. A air heat pump is included as standard. We would like to switch to geothermal. The builder offers deep drilling and brine heat pump for an extra 9,500€. Motivated by the threads in the forum, we wanted to install a trench collector on our own. However, in that case, we would only get 6,800€ reimbursed for the eliminated drilling. Therefore, we would probably take the drilling after all and rely on BAFA funding.

Are these prices realistically related?

Thanks and regards Christian

Hard to speculate from a distance. When it comes to the heating system, they charge well for the extra effort on an unknown system (to put it mildly)... but what's the point in getting upset about it.
€5500 more for the brine-water heat pump after the Bafa deduction will heat your place for at least 15 years (€30 more per month for an air-water heat pump vs. brine-water heat pump); so it's a matter of personal preference.

The BAFA funds not only brine-water heat pumps with ground probes but any brine-water heat pump. With probe 4.5T€, without probe 4T€ in new buildings (program "Innovation funding"). Those who build a basement and install a trench collector or install a trench collector themselves are likely to profit from the funding (of course not if the developer calculates everything unrealistically expensive).

I can't say much about your prices. They generally feel rather expensive. Why should the heat pump for a brine-water heat pump be 2700€ more expensive than an air-water heat pump? This is hard to understand even with volume advantages; it is more likely a factor of "upgrading" and/or "I don't want it." But that is probably how it is with developers. The same applies to the KFW issue; after all, many roads lead to Rome.