Architect or developer? Which is more affordable?

Developers are usually cheaper because the construction method differs from that with an architect. BUT: 2x exactly the same house = architect is cheaper

Now it is so that a large new house was built with an architect in our family two years ago and [...]
Now our consideration:
If we were to build with this architect as well and do a so-called "piggyback solution," i.e. ask the same affordable and good craftsmen again whether they would do the same again for, e.g., a 4% price increase?

Do I understand correctly (I hope not): You want to have a house from your relatives copied 1:1 by their architect onto your plot, and the reduction of the architect's fee to a repeat fee (I believe that saves about 7% or so) is supposed to make this waiver of individual planning "worth it"?

It is important in any case not to be misled by the costs that are visible at first glance (amount of the offers). With good planning, both approaches are certainly feasible, but ultimately only the final invoice after completion of the construction project "at the bottom line" counts. A larger number of individual trades (i.e., more interfaces) always represents a higher risk, among other things, regarding the subsequent assertion of defects, as soon as the burden of proof falls on the client after acceptance. This should definitely be kept in mind, because the organizational/contractual effort required to minimize the risks as much as possible is naturally higher with several interfaces. Whether it is therefore worth paying a potentially higher price for the general contractor is always a matter of the individual case (especially the specific implementation and the experience of the parties involved); this can hardly be assessed in general.

Thank you very much for your previous answers! We are thinking of a different, smaller single-family house than the one our relatives built. But we thought we could ask the same shell builder, window maker, etc. again without doing a lot of new tenders...

But from what we hear, the companies are so busy that it will be difficult to get good prices. Probably the companies that built for our relatives in 2014 have no interest in building our house in 2018 :-(

We are now considering reducing from 140 to 130 m² to save costs and be able to afford the construction with the general contractor. The offer from the general contractor so far is 340,000 euros for 140 m² including a white tank and good standards (large window areas, wooden windows, parquet, good room heights).

We would like to end up at a maximum of 320,000 euros...

Savings ideas: leave out the fireplace (5,000 euros), leave out the white tank if possible, manage the construction ourselves (architect from the family, but unfortunately with little experience in single-family houses).

Another question: For about +7,000 euros we could upgrade to KFW 55. And we would simultaneously receive a 5,000 euro repayment subsidy of the L-Bank for the funding loan. Do you think anyone still needs a fireplace in a KfW 55 house at all? Or are the heating costs (even in "bad times") always manageable there?

Thanks dear builders for your good and helpful advice!! I wish you a nice afternoon.

Take over the construction management yourself

Will not work, because the site manager is not for you, but for the general contractor.

needs a chimney

No house built in 2017 needs one, a chimney is a luxury and has nothing to do with heating.

We would like to end up at max. 320,000 Euros

We are at 324,000 for 134 sqm with a white bathtub, chimney, air-to-water heat pump, and controlled residential ventilation.
For that without bathrooms and without tiles or other floor coverings.

The offer from the general contractor so far amounts to 340,000 euros for 140 m² including a waterproof concrete shell and good standard (large window areas, wooden windows, parquet flooring, good ceiling heights)

Good wooden windows are an extra cost item, for which I would rather choose aluminum. Show us how we should imagine the house at this price in pictures, that is: please post floor plans and elevations.

We are now considering reducing from 140 to 130 m² to save costs and be able to afford building with a general contractor.

You either need space or you don’t. Where you can save well are completely different things: bay windows, corner windows, shower in the guest bathroom, fireplace, double garage dance hall and the like.