Additional construction costs ... but which ones?

How do you come to the conclusion that you don't need electricity for drying? Dehumidifiers run on electricity and not on gas heating

That was my interpretation based on PayDay's post. If the drying is done with electricity after all, then 30€ seems a bit low to me.

Temporary construction electricity was just under 900 kWh with us without screed drying - so nothing like 30 euros.

Screed drying with the heat pump then cost over 3000 kWh

It's just extremely different. The screed heating itself almost always takes place via the primary heating of the house (gas/electricity, after all, this is already available). However, the moisture does not just disappear because it is warm. Drying devices of course require quite a bit of electricity. Whoever manages to get the screed in during summer can also work without a dryer. Whoever is willing to wait a few weeks longer can also do without, etc... everyone has to decide that for themselves. How much electricity is actually used in the end varies a lot. For us, it was 30€.

Our KfW man cost 930€, came at the end of the construction, took 3 pictures, and checked if the ventilation system was working properly. He gave us the confirmation that everything was fine and the invoice arrived. It might be different now in 2016 (compared to November 2015).

Especially in summer you need dehumidifiers because you simply can't get rid of the moisture

Or you have a stupid winter like now, then you need some too.

Do you still know approximately how much the production of the construction site electricity exclusive of consumption cost you?

Which production? In the power plant?