Traditionally, radiant systems have been used for heating by circulating a heated fluid through PEX or copper pipes most likely in the floor which provides heating. The radiant energy transfer is caused by a warm surface giving up it heat to a cooler surface (your body). This radiant energy travels through space without heating the space itself. It only turns into heat when it contacts a cooler surface. Radiant cooling works very much the same way, except the heat transfer is in the opposite direction. Instead of a heated fluid, a chilled fluid is circulated through capillary tubes located in the ceiling or walls. The capillary mats in the ceiling or walls then absorb the thermal energy radiating from people and other sensible load, lowering the mean radiant temperature of the room.
The major difference between cooled ceilings and air conditioning is the heat transport mechanism. Air conditioning uses convection only using air distribution through duct work, but radiant cooling uses a combination of radiation and convection. The amount of radiant heat transfer can be as high as fifty five percent, while convection accounts for the remainder. read more