Build according to KFW 70 or the Energy Saving Ordinance 2014

Glad the floor plan is liked. Nice to hear something positive for a change. The architect is planning with gas and solar; we actually wanted to inquire about geothermal energy as well. It's currently also being subsidized. It would be our favorite. Several acquaintances are very satisfied. The architect says it will be significantly more expensive despite subsidies. The companies would just add the subsidy costs on top again. That's also a statement I don't understand. Regarding the wall construction, 17.5 brick + ETICS (Styrofoam) is planned, although I prefer mineral wool. But according to the architect, it is significantly more expensive.

Yes, heat pumps using geothermal energy, that is brine/water via ground collectors or ground probes, are significantly more expensive, as drilling for ground probes alone incurs additional costs of around €8,000. Furthermore, your primary energy factor for the heat pump (currently 2.4 for electricity) divided by the annual performance factor of about 3.5 with 0.68 is still more than three times as high as that of the pellet heating system. Styrofoam, i.e. EPS, is already the insulation material with the best price-performance ratio. Sand-lime brick should be cheaper in the wall structure than conventional bricks.

But let's not compare apples and oranges... A seasonal performance factor of 3.5 with a brine-water heat pump is hardly achievable deliberately... >4.5 can be assumed, especially when talking about the subsidy. It amounts to 4.5 T € and is intended as an incentive...

Taking only the first one and then just the extremely expensive drilling as a comparison is very hypocritical.

What kind of roller shutter boxes are installed when building according to the KfW 70 standard? Our architect always says that these are much more expensive than normal ones. He also says that with KfW 70 or better, they can only be opened from the outside. Is that correct?

That depends on the entire building. For KfW 55, we do not require roller shutter boxes that can only be accessed from the outside for inspection. Therefore, the statement cannot be generally true.