1.7.10 Radiant Heating and Cooling
Radiant cooling: Cool a space by absorbing the heat radiated from people, equipment, etc. When the floor is cooled, it is referred to as radiant floor cooling; cooling the ceiling is usually done with radiant panels. Heat is taken away by circulating water in the embedded pipes.
Radiant heating: Heat a space by radiating heat directly to the occupants. When the floor is heated, it is referred to as radiant floor heating. Both hydronic and electric radiant heating systems are available.
Hydronic heating and cooling: Fabricated ceiling panels, ceiling/wall/floor mats, and custom floor tubing along with greater tubing longevity and digital control systems have made systems viable. The key to tubing longevity is an oxygen barrier in the polyethylene (PE). The barrier keeps oxygen in the water from corroding equipment. PE floor tubing is typically placed 9 inches on center, embedded in a top screen.
Electric heating: Typically floor systems. Both electric cable systems and prefabricated mats with embedded electric cables are available; both are built in to the floor. Electric radiant floors are most efficient and cost effective with floors with a high thermal mass.
The perception of comfort is a function of radiant surface temperatures, air temperature, air velocities and moisture levels. In most buildings, the only variable controlled is the air temperature. Radiant floors take advantage of effective temperature. Successful applications will mandate a thorough commissioning process.
Radiant systems can cost less than conventional systems due to minimized space for mechanical equipment.
A combination of radiant cooling and displacement ventilation can achieve high overall operational building energy efficiencies. Radiant floor and ceiling systems are quieter and less visually intrusive because of eliminated air duct work.
To be effective, components of radiant cooling systems must be maintained at a temperature very near the dew point within the space, and the indoor air must be kept dehumidified. This is particularly crucial in hot and humid climates to maintain comfort and avoid condensation. Radiant cooling floors are best for large-volume, tall, hardscape spaces with significant solar load.
1.2.2 Displacement Ventilation,
1.2.9 Underfloor Air Distribution
1.6.3 Ground / Water Source