Hydronic Radiant Cooling Piped cold water can cool in arid climates or humid climates if dehumidification equipment is added.  Comfort relies as much on radiant heat transfer as it does on air temperature. Conventional air conditioning units are only designed to control air temperature. Because radiant energy travels through space without cooling the air itself but rather objects, hydronic radiant cooling systems separate ventilation from thermal conditioning, providing fresh air and conditioning independent from each other. Radiant cooling is a sophisticated approach to comfortable, high-efficiency cooling.
The human body transfers heat in three different ways: radiation, convection, and evaporation. Thermal comfort is when these three factors are in thermal neutrality. Ideally 50% of body heat is cooled by radiation, 30% by convection and 20% by evaporation (sweat and breathing through the mouth).With an ideally designed conditioning system, the occupant would not know if it is cooling or heating. Radiant cooling falls in the "air-and-water" category where the outside air ventilation system provides only the necessary fresh air while the hydronic thermal distribution system with a radiant heat exchanger provides the cooling. Therefore radiant cooling or heating systems address both, the convection and radiation factor of body heat whereas conventional air conditioning mainly address the convection factor by high air circulation. There are currently three different hydronic radiant cooling systems available.The panel system is the most common radiant system. The panels, usually aluminum, can be surface mounted or embedded on floors, walls or ceilings. The capillary tube system characteristics are small closely spaced tubes that are embedded in plastic, gypsum, or mounted on ceiling panels. The many tubes allow for better heat absorbing distribution and a thinner ceiling. And finally, the concrete core conditioning systems with tubes embedded in a concrete slab allows for peak load shifting because of its thermal storage capacity. This could be used also as a wall mass. In each of these systems, the water is mixed in a glycol solution and cooled by an air-to-water heat pump, a cooling tower, a ground-source heat pump, or even well water. Since the radiative surface is typically a whole floor or ceiling surface, the water can be as warm as 65º. 
With professionally configured and installed units the system can be used in any climate, however because of the risk of condensation in very humid areas proper design and installation may be even more critical. These systems are most economical in areas like Arizona where the humidity is less than 15%. A forced air system, such as an air handler or dedicated fresh air system, may need to be incorporated to remove humidity and pollen. Some systems have arelatively slow system response. Once room surfaces reach a desired temperature, however, they tend to maintain that temperature with relatively little extra energy.
Not Applicable
The preferred installation is ceiling mounted, as this reduces air stratification, facilitates collection of condensate, and involves less structure. The piping network is tied into a heat transfer source such as a heat pump. Tthe transfer medium can also cool the coil for an air handler to provide air movement.
A new and seldom-used technology, radiant cooling is not regulated in the codes like radiant heating.
Not Applicable
The preferred installation is ceiling mounted, as this reduces air stratification, facilitates collection of condensate, and involves less structure. The piping network is tied into a heat transfer source such as a heat pump. Tthe transfer medium can also cool the coil for an air handler to provide air movement.
Not Applicable
Due to the high heat capacity and density of water, thermal energy can be transported in water in pipes with little pump power, saving approximately 70 to 80% of fan power normally used to condition a building. This alone reduces the peak-power of the air-conditioning system by about 30 to 45%. There is no space conditioning equipment necessary on exterior walls, and the panel system can use the automatic sprinkler system piping in some multi-family dwellings. Radiant cooling panels with minimum fresh air supply is a draft and free system that also eliminates fan-coil and induction unit noise. Cooling is more evenly distributed, and drafts can be eliminated. There is less exfiltration of cooled air when doors or windows are opened. Prices vary extensively depending on climate, existing conditions and system. According to distributors, ammortisation within 5-7 years is common. | 
