Radiant cooling cools a floor or ceiling by absorbing the heat radiated from the rest of the room. When the floor is cooled, it is often referred to as radiant floor cooling; cooling the ceiling is usually done in homes with radiant panels. Although potentially suitable for arid climates, radiant cooling is problematic for homes in more humid climates due to condensation on the panels when their temperature is below the dew point of the air in the room.
Most cooling home applications in North America have been based on aluminum panels suspended from the ceiling, through which chilled water is circulated. To be effective, the panels must be maintained at a temperature very near the dew point within the house, and the house must be kept dehumidified. In humid climates, simply opening a door could allow enough humidity into the home to allow condensation to occur.
The panels cover most of the ceiling, leading to high capital expense for the systems. In all but the most arid locations, an auxiliary air-conditioning system will be required to keep the home’s humidity low, adding further to the capital cost. Some manufacturers do not recommend their use in homes.
In addition, the limited use of radiant cooling in the United States U.S. creates concerns about the quality and availability of professionals to install, maintain, and repair a residential system.
Despite these caveats, there may be cases where cooling is appropriate for homes, particularly in the arid Southwest. Radiant cooling systems have been embedded in the ceilings of adobe homes, taking advantage of the thermal mass to provide a steady cooling effect.
Homes built on concrete slabs are prime candidates for radiant heating systems, and radiant floor cooling takes advantage of the same principle using chilled water. This is particularly economic in homes with existing radiant floor systems. Again, condensation is a concern, particularly if the floor is covered with heavy carpeting, and the effect is intensified by the tendency of cool air to collect near the floor in stratified layers. This limits the temperature to which the floor can be lowered.
Despite that limitation, a study performed by DOE’s Oak Ridge National Laboratory found that some early morning cooling of a home’ s concrete slab, combined with nighttime ventilation, could shift most of the cooling loads for a house to off-peak hours, reducing the peak demand on electric utilities.