Fixed price commitment - price increase after expiration?

Well, and by the way, it is also the question whether the clause is really one-sided? It guarantees a fixed price for a certain period of time and afterwards the price is then adjusted. Expecting this period to be excluded from the price adjustment is actually naive. Whether the GU has already factored this in beforehand is pure speculation.

Many builders, who perhaps have calculated rather tightly, will likely be badly affected by such price gouging, and it may endanger the entire construction project. Or they may have to settle for the lowest standard. A pity, really.