Don't give in just yet till you hear both sides: First of all, heat doesn't rise, but hot air does, and thats a big difference when it comes to radiant heated floors vs scorched air heating systems...the comfort level of a radiant floor is Nirvana compared to the convective drafty currents of hot air blown in thru vents over your head only to collect at the ceiling. Radiant floors are like the sun. Conversely,....cold doesn't fall, cold air falls, which is why radiant cooling in the ceiling makes more sense and successfully and uber-efficiently done over in Germany. To get around the damp/moist factor, they employ window sensors that simply adjust temp of the water running thru the ceiling panels so that the aluminum ceiling-panel system (or concrete ceiling) "coldsink" doesn't sweat nor worsen the humidity inside. Radiant cooling is a brilliant idea since less energy needed for the few times a day the air is recirculated thru much smaller mini-duct system to circulate and dessicate the air. Apparently, the cost savings can be over 50%....but, its that startup cost as with any high-efficiency system that keeps us from practicing what we preach. Until we pay what the Euros pay for energy, the majority of installs for new construction will continue to use poorly-efficient and outdated methods of heating and cooling. But the radiant cooling system is here and it works. Very 'green', uber-efficient, and probably the right way to go if you can afford it. And yes, wouldn't it be great to use the existing radiant system already in the floor.....all I know is that hot air rises (Not heat) and cold air falls.