Hydronic Heating and Cooling

Indianapolis Airport and NRDC Headquarters
Indianapolis Airport (left); NRDC Headquarters (right)

Hydronic heating and cooling refers to the use of radiant surfaces to provide thermal comfort and is often part of a dual-path approach where the ventilation requirements are met independently from thermal comfort. Fluids fundamentally move energy more efficient than gases, thus fan energy is replaced with lower pump energy. However, benefits for hydronic systems go far beyond this simple energy trade-off. Hydronic systems allow a building's own thermal mass to store energy allowing the mass to be "charged" during more appropriate times. Furthermore, since human comfort is seven times more responsive to radiant temperature than convective (air temperature), similar thermal comfort can be provided at higher space air temperatures.

The design for Cornerbank, a small branch bank office, included an exposed radiant floor throughout the central core of the bank. This solution worked better with the large volumes created by the vaulted ceilings associated with the daylighting clerestory. In this design, the in-slab radiant was served by a ground source heat pump system. The Indianapolis Airport also implemented extensive use of hydronic heating and cooling. The system was a two pipe changeover configuration primarily intended to counteract the envelope load from the extensive use of glass.