I suppose an uninsulated concrete floor slab (as in the current situation with this building) is always going to 'feel' cold compared to the room.
With being completely enamoured with UFH (put it in the last 2 places, really miss it in this farmhouse, so have put it in the stone barn conversion) perhaps we should go for a thin layer of foil-faced PIR and then UFH pipes to avoid too much of a floor build-up, whilst still doing the downstand EWI to foundations to minimise heat loss.

Posted By: Dominic CooneyI suppose an uninsulated concrete floor slab (as in the current situation with this building) is always going to 'feel' cold compared to the room.

The feel of a surface is largely to do with its thermal admittance. Some surfaces, like concrete or stone, are inherently 'cold' because they conduct heat away from your hand or foot quite quickly. Timber or EPS or cork conduct heat away less rapidly and feel 'warm' because of this. Hence people like carpet and wood floors and cork mats in bathrooms etc. Changing the surface will be cheaper than installing UFH, although it doesn't do quite the same job.