Construction costs are currently skyrocketing

Our plumber plans the flow temperature of the heat pump at 35°C and pipe spacing always at 20 cm. I then asked for a cost increase calculation for around 30°C. (see attachment) I received this without further explanation. Before I start a conversation/discussion with him, I would like to have the following points clarified:

1) I understand that under the item "Length" the planned pipe length for the room is indicated. If several heating circuits are planned there, I have to multiply the "Length" by this factor. Is that correct? 2) I understand that more material (pipes, distributors, fastening clips) and more work incur costs. Have I forgotten anything? 3) If I have understood 1) correctly, I come to a total length of 1,059.71 m and 17 heating circuits at 35°C and 1,929.2 m and 27 heating circuits at 28°C flow temperature. The difference is 869.49 m of pipes and 10 more heating circuits. In which range should we currently price this additional output? Do construction costs skyrocket here or is this trade not affected by this?

The automatic locking with A-opener of the front door has become €40 cheaper than planned...

OT: Our coffee beans have also dropped from 20.30 to 19.80 ^^

in the new version, the bathroom stands out above all. It stays cold there... The plans raise some questions. If you want to delve deeper into that, it's best to start your own thread.

oh yes: The variant with 28°C flow temperature is supposed to cost 3,980 euros more.

in the new variant the bathroom stands out above all. It stays cold there...
The plans raise some questions. If you want to delve deeper into this, it's best to start your own thread.

A rough assessment is enough for me for now: Is the 3,980 euros justified?

I am very happy about details here:
:)

I would now consider it normal and fair. The additional price is about €18.77/m², we paid about €9.6/m² in 2015.

If you heat with 28°C instead of 35°C supply temperature, say 15% more efficiently, you will consume 4,462 kWh per year instead of (150m²*35kWh/m²/a) 5,250 kWh. Which is of course a lie, because a significant part of the heat in low-energy houses goes towards hot water, but whatever. So in kWh electricity, this is a saving of 197 kWh (788 kWh heat saving with an annual performance factor of 4). At 40 cents/kWh heating electricity, that is just under 80 EUR savings per year.

You can calculate when the 4,000 EUR extra cost pays off. You will have to get pretty old ;)

I may be mistaken... but after seeing that the plasterers place their scaffolding/cross braces on power lines laid on the ground without batting an eye... I can’t imagine that the screeders manage not to step on the heating pipes when pouring cement screed with a laying distance of 10cm (and less)...