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)...
