What are possible disadvantages of underfloor heating/cooling? Is it better than the widely used air conditioning systems? Why?

For under floor cooling heating normally there are following disadbantages.

1. There is always raised floor which in many cases not applicable.

2. The ducts system is normally not feasible under raised floors

3. maintenance issue

4. air balancing is diffucult

5. if the throw is not good then all cooling will remain at very low level and if return is also at floor than it may take all supply air before diffusing in the area.

6. normally this is used in electrical data room or data centers in POD area where the equipments are at height and at raised floor

7. if return is at flooring also then lot of duct is being sucked by return air grilles

the hot air have low density (normally goes up  )as you know and the cooled air has higher density(it stays down until its get hot)

so its mush better to supply cooled air from the floor and have the return from the ceiling(the air circulation will be better)

but its higher cost because you will only need false ceiling you will need also raised floor

this system is very common in usa but i have only  seen it once in Egypt in a big project