I am editing this, noticed that the explanation wasn't clear enough!
Hello!
I'm considering how to best insulate this area with regard to moisture formation and the best possible insulation performance.
In the picture, you can see the entrance located on an extension, which is a cast slab resting on two pillars and embedded in the house's foundation wall. Now we have enclosed two of the sides with masonry and will have a door on the third for some storage space. Now that it's starting to get a bit colder outside, the floor is getting fairly cold, so the question is how do we insulate this space in the best possible way (I mean the "ceiling" in the space that is under the entrance floor), I am thinking about insulation material and air gaps, etc. The space is about 7 sqm.
Regards, Fredrik