One must consider: The place is new. Everything is still relatively damp. The underfloor heating is also not a high-speed system like radiators.
However, it can efficiently heat large areas at low temperatures. But initially, it requires a lot of energy to, so to speak, get moving.
Compare this to an oil tanker or container ship. Initially, it is hardly movable. But once underway, it is enough to run the engine at low power.
All of this consumes large amounts of kWh at the beginning... over the entire heating period it will decrease, and yes, only after 1-2 years when the construction moisture is gone will the desired values be reached.