Renovate an old building or build new? Experiences?

150k for the renovation seems very little to me, especially since the entire heating system is supposed to be new, and the facade is also supposed to be insulated.

In 2022, we once asked an energy consultant for a house from 1928, and the estimate to get the house towards KFW85 was 450k. And we live in an area where construction can be done quite cheaply.

Ultimately, the old building with renovation would cost about €590k + €40k incidental purchase costs, totaling €630k, while the new building with some special features would cost €640k + €50k incidental purchase costs, so €690k.

I believe you about the new building,
but with the old building and renovation by companies, there are endless additional charges. Or are you renovating yourself?
Before you know it, every trade adds something on (we didn’t see that beforehand, blah, blah ...).
My decision would be the new building, because it’s more predictable.

Plot size? Orientation of the living rooms + terrace regarding cardinal directions? Traffic noise? Road connections, neighbors, floor plan - correspondence to needs, ceiling heights ... and so on. I can think of many more criteria, money is rather secondary.

Old building vs new building
Living area: 130 sqm - 142 sqm
Plot: 360 sqm - 320 sqm
Garden orientation: west - south/west
Busy side street - quiet residential area
Floor plan: both top, new building has nicer attic studio and larger kitchen

Electrical work plus a new bathroom for 20k could already be tight. Had you already included front doors in the 150k further up?
With old buildings, there are also surprises that need to be planned for. What about the water pipes?

......with that price difference, the decision for the new build would be easy for me. At least then you have peace of mind initially.

The electrical work is done by a very good friend, I would only have to buy the materials and might give him 1-2k€ as a tip. But well, together with the bathroom it could then rather be 25k€. By renovation, I meant the front door, and further down the interior doors.
Unfortunately, I can't say anything about the water pipes. At least the basement is completely dry.
This "peace of mind initially" is already appealing to me, since I can’t really put much aside for reserves at first.

Floor plan: both great, newly built nicer attic studio and larger kitchen

If your nerves are strong enough, feel free to post both floor plans. If they get torn apart by the locals here, it might show which floor plan is more "top". ;)

If your nerves are strong enough for it, feel free to post both floor plans. If they were torn apart by the locals here, maybe it will show which floor plan is more "top". ;)

Well, just top for my needs. But here you go.