S06 -- Radiant Heating and Cooling (SI)

Panel heating and cooling systems use temperature-controlled indoor surfaces on the floor, walls, or ceiling; temperature is maintained by circulating water, air, or electric current through a circuit embedded in or attached to the panel. A temperature-controlled surface is called a radiant panel if 50% or more of the design heat transfer on the temperature-controlled surface takes place by thermal radiation. Panel systems are characterized by controlled surface temperatures below 300F (150C). Panel systems may be combined either with a central forced-air system of one-zone, constant-temperature, constant-volume design, or with dual-duct, reheat, multizone or variable-volume systems, decentralized convective systems, or in-space fan-coil units. In decoupled systems, the air system provides ventilation air and meets dehumidification needs. In hybrid (or load-sharing) systems, the air system may provide significant additional capacity (e.g., where cooling loads exceed the capabilities of a radiant slab system). This chapter covers temperature-controlled surfaces that are the primary source of sensible heating and cooling in the conditioned space. For snow-melting and freeze-protection applications, see Chapter 52 of the 2023 ASHRAE Handbook -- HVAC Applications. Chapter 16 of this volume covers high-temperature panels over 300F (150C), which may be energized by gas or electricity. PRINCIPLES OF RADIANT SYSTEMS Heat Transfer Factors Affecting Heat Transfer Panel Design General Design Considerations Hybrid Systems RADIANT HEATING AND COOLING SYSTEMS Hydronic Ceiling Panels Embedded Systems with Tubing in Ceilings, Walls, or Floors Electrically Heated Radiant Systems DESIGN PROCEDURE Controls