The problems with humidity, diffusing from the soil into the house is already known for a long time. Less known are the problems with radioactive gases like Radon and sulfur dioxide gas in some countries. The picture hereunder shows where sulfur dioxide is emitted by the vulcanic underground (red squares).
Every problem has a solution and the Daliform group came with a good idea. Under the floor, they install cavities, manufactured from plastic, to be able to ventilate these unhealthy gases.
On top of the ventilated space, thermal insulation has to be installed because we do not want to heat the ventilating air with expensive energy.
Although the above solution works, the combination ventilation / thermal insulation can be done with (closed cell) cellular glass. GLAPOR cellular glass is 100% impervious to these and other gases (like ordinary glass) and eliminates the need for a ventilated space. On top of that, it functions of course also as thermal insulation with a high load bearing capacity.
I would be surprised if the combination of the cavities / XPS thermal insulation is not a lot more expensive than GLAPOR cellular glass, installed on the concrete with hot bitumen. And we may expect also a much longer life time with the cellular glass solution, which is also proven to be ecological.