Underfloor heating for which rooms?

Hello everyone,

We are currently starting the renovation of an old house, to be precise, we are emptying it at the moment (roof structure, interior walls, floors, etc.). The house currently has an old oil heating system with radiators in every room... The heating system is to be replaced by an air heat pump with underfloor heating, and here there is a fundamental question... The rooms were simple, the floor was completely made of a wooden structure, just by removing it we gained about 10 cm, so enough space for underfloor heating. But the entrance area, i.e. the foyer (~9m² on the ground floor, 9m² on the first floor) consists entirely of concrete + tiles... Removing it would be a huge effort. Therefore, we are currently considering whether it might even be possible to leave this area unheated, or simply use low-temperature radiators?

Each floor would thus be heated over about ~70m² (the individual rooms), and have ~9m² unheated... Is that okay???

Hello "hachi",
the current planning requires careful consideration of whether the remaining areas can provide heating to the entrance area or not.
Just have the heating engineer calculate it once. But be cautious!
When taking a closer look at the topic of "underfloor heating," one quickly comes across the term "cold spots." Unpleasant to stay there, even if the desired room temperature can be achieved on average.
1. If you specify that the construction there consists of concrete + tiles, you have (hopefully) also checked this information?
2. How thick are the tiles + tile adhesive?
3. What are the visual requirements in the entrance area?
Is it designed as a passage (without a door and geometric division) and is a continuous installation of a visually uniform top layer expected later?
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It is better to consider alternative constructions and thus additional heating of the entrance area at the current (early) stage of construction progress than to later regret the now impossible with dissatisfaction (figuratively speaking).
On the 1st floor, I would still understand heating via adjacent areas, but not on the ground floor if there is an access to the outside area there.