HOAI or why architects have no interest.....

Sorry, forgot the details ;-). Yes, it is actually a detached house, new build about 150 sqm according to KFW40 (presumably). In terms of content, all are comparable; with the 3rd architect, even service phase 5 is included, but in return, the construction supervision by an energy consultant is omitted. Offers 1 and 2 only up to service phase 4. These are actually lump sum prices (wording in the offers). We choose the craftsmen ourselves. We only want the architects until the approval – after that, we take over.

I find the price for the geotechnical investigation amazingly cheap. With us, it doesn't cost less than €1,000 gross for 2 drillings. 3 holes cost directly €1,500.

I think you misunderstood that. The architect just wanted €200 for forwarding the relevant plans and data to the geologist. Apparently, nothing has been drilled there yet.

Seems to vary a lot by region as well. Around here, an architect wouldn't even give you the time of day for something like that. It's not uncommon for someone to say they won't build for less than budget xy. From what I hear in the area, most architects barely schedule an appointment unless you already have the land secured.

1) never signed a contract that is billed by the hour
2) never signed a contract that is billed by the hour
3) look carefully at what is stated as the scope of services in the offer, if there is no [HOAI] contract you cannot refer to what is stated in the [HOAI] regarding the service phases.

Actually - okay, then my comment is withdrawn, as it is pointless ;-). What surprises me is the price difference between the architects. We have not accepted any offer yet, since apparently it can be done cheaper. Whether cheap is ultimately good, we will find out through the discussions that take place beforehand.

The services are indeed listed according to the HOAI phases, i.e. planning and cost estimation, design with cost calculation, approval - as it should be. And that for all three. Nothing is listed regarding fees outside the price, so no hourly rates. Understandably, as a layperson, one becomes skeptical when such huge price fluctuations occur despite seemingly identical services.

Understandable that as a layperson, you become skeptical when such huge price fluctuations occur for seemingly the same services.

That could be because the architects each calculated differently how much from existing plans they can incorporate into your planning.

In that regard, I am a complete layperson, but I would then look closely at what is exactly named as the "subject of the contract" and scope in the contract. For example, whether a room program appears there, or already some kind of standard house, etc. Because I somehow cannot imagine a completely free design according to HOAI with 2-3 preliminary drafts and all refinement steps.