Construction time overrun 34 months - compensation states 500€/month

Briefly on the side. Heat pump electricity consumption in one month is 1600 kWh. Does that sound right?

In January? In BW? 150m²/Energy Saving Ordinance building?
1600 kWh * COP (at that time of year approx. 3) = 4800 kWh = approx. 50 kWh heat /m² = too much for one month, even January, but in new buildings due to screed drying quite possible. If the value still comes from the construction phase, it cannot be used as a reference anyway, as the conditions and usage are completely different.

If after 2 years you come to a total of 20-25 kWh electricity per m² per year, everything is fine.

Yes, from January 16th until the day before yesterday

Status 22.02.18 - follows in about an hour
Status 07.02.18 - 5596 kWh
Status 16.01.18 - 4361 kWh (until then it was running in the heating program for the screed and also without the outdoor unit, as it was incorrectly connected)

How does the calculation go?
4800 kWh divided by 150 m²... then would come out to 32

Were there any personal contributions?
What caused the 3 months delay?

Own work only started “afterwards“

Delay was caused by the site manager, as he was not able to coordinate everything properly.
When you have construction sites from Frankfurt down to Mannheim and even come from Koblenz, it's clear that you lose track.
The guy is simply useless.

Always forgets everything, does not take care of promised things, etc.

Sometimes I called the trades and informed them that the previous trade was finished and they could start.

The first delay occurred already in the shell construction because too few bricks were delivered.
Then the shell builder couldn’t work for 2 weeks, etc. etc.
It dragged on like that throughout the entire construction.

They kept coming up with the construction boom and everyone being fully booked, etc.
Sure.
We were the 3rd in the construction area and are now one of the last to move in.
Out of about 22

Perhaps an open conversation would help more. You can clearly say that you have the impression that the construction company is trying to take advantage of you. Address the mentioned points openly and say that it apparently has always been saved at your expense and now there is again an attempt to circumvent the contract to your disadvantage. It is best to do this in a direct conversation and not by email or letter. Everyone can then put their cards on the table, and hopefully, you will not part ways upset in the end. After all, you also want 5 years of warranty without constant disputes. A good relationship is worth a lot, but please without being taken for a fool, because that does not help.