Questions about underfloor heating with geothermal energy

Hello everyone.

As a first-time home builder, many questions arise. One has been particularly on my mind lately.

We have a KfW70 house with good insulation (16 cm masonry and 18 cm insulation), underfloor heating via a ground source heat pump.

When I take my little one to kindergarten in the morning, I am always surprised that the tiles in the kindergarten entrance area feel noticeably warm.

Our tiles, for example in the living room, on the other hand, feel noticeably cold. The temperature sensor in the living room is set to 20 degrees, and this temperature is maintained, which is nice and good. But why do the tiles feel noticeably cold?

Is it because, on the one hand, the kindergarten is not heated with geothermal energy and, on the other hand, it is not insulated like our house?

Of course, the underfloor heating is supposed to maintain the room temperature (which it does) and not warm the feet. But where is the explanation for the "noticeably cold tiles"? Our heating system naturally doesn't have to work as hard because of the good insulation.

An explanation would still "put me more at ease."

Well, entrance area = cold air keeps coming in, the heating has to blast to maintain the room temperature anyway. There are said to be people who open the windows wide in the dead of winter so that the underfloor heating finally gets going properly and the tiles warm up...

It is completely normal. It has nothing to do with the heat generation (whether gas, district heating, heat pump). As you have correctly recognized, it is due to the good insulation. The underfloor heating is supposed to comfortably temper the room. Because of the good insulation, it achieves this with a low flow temperature (water temperature) in your case. If you were to turn up the underfloor heating so that the tiles become noticeably warm, you would be sitting in a sauna. So it is completely normal in a well-insulated new building.

Is it an "old" kindergarten where the heating might be designed for a high flow temperature?

It is as DerBjörn already says. You have a modern heating system in your house with low flow temperatures. And the pipe spacing of the underfloor heating is certainly quite close. In the past, underfloor heating was not laid so closely, and logically a higher flow temperature is necessary to heat the floor. You will notice this higher flow temperature in the kindergarten. For example, in our case, the highest flow temperature at the coldest minus degrees was around 33 degrees. Of course, somewhat less reaches the surface of the floor – so significantly below your body temperature (feet). That is why even in a warm and cozy room the floor still feels cool (primarily with tiles).
Best regards

May I bring up the topic again? Something is not right here.

The person who installed the heating told me just yesterday that the system is set with a target room temperature of about 20 degrees, so that I can turn the room thermostats in the living room and bathroom all the way up. If it then gets too warm, I can adjust the target room temperature on the system. Said and done.

Suddenly, the electric heater started to work, but at "full blast" (= power consumption!).

After looking around in the system's menu, I then found a target room temperature of 35 degrees. So if the thermostats in the living room and bathroom are fully on, they want to distribute 35 degrees.

In the end, I reset the system (layman’s fear of changing something that I can no longer fix) to how it was: thermostats in the living room at 22, in the bathroom at 23 with a set target room temperature of 35 degrees.

This morning I come into the living room and: 18.8 degrees. Why???

I would like to hear your opinion on the attached photos.