There are a number of different ways of insulating a concrete floor. Much depends upon whether the floor is new or existing; how the floor will be used; the type of construction, and what you want to achieve.
Is the insulation strong enough?
If your concrete floor is for industrial or heavy duty applications, then any insulation you use needs to have a high compressive strength – to take the weight of whatever is above. Typically the insulation would be situated below the slab and below the damp proof membrane for heavy duty use, whilst normal domestic buildings would have a higher performing, lower compressive strength material above the slab.
How much space do you have?
How much space you have is important. For example, if you are digging down to lay a new slab, then you will need to leave room for the insulation. The thicker the insulation, means the more material you will have to excavate and dispose of. If, however, you are insulating on top of an existing slab, then you will need to consider things such as whether you need to replace or remove skirting boards, door jamb heights, ceiling heights etc. Once again, a thinner insulation such as vacuum insulation may be a more cost-effective or more practical option in the long run.
What u-value do you want to achieve?
You also need to work out what U-value you want to achieve. This is determined by the Perimeter / Area or P/A ratio and soil type (the Middle East is predominantly sand). Sand will affect the thermal performance as it has a high thermal conductivity when compared to clay, meaning more insulation would be required to achieve the same U-value). A P/A calculates how much of the floor perimeter is exposed to unheated or external spaces as a proportion of its total area. The more exposure (the high ratio), the more insulation is needed to achieve a particular U-value.