Occupant’s thermal comfort in a radiant ceiling cooling room with hot wall surface

Abstract

A radiant ceiling cooling (CC) system integrated with a mechanical ventilation system was extensively applied in a modern office in a glass curtain wall building. Thermal comfort in a radiant ceiling cooling room with mixing ventilation (MV) or underfloor air distribution (UFAD) was investigated by objective measurements and subjective questionnaires. The external wall surface temperature and mean radiant temperature were 33.9–34.6°C and 27.2–27.4°C, respectively, with a heat transfer of 41.5 W/m² from the external wall and 37.8–38.6°C and 27.4–28.2°C with a heat transfer of 69.5 W/m² from the external wall. The indoor air velocity in the occupied zone was 0.17–0.23 m/s in the room with CC+MV and 0.09–0.16 m/s in the room with CC + UFAD. There was a considerable difference between occupants’ thermal perceptions with different distances away from the external wall. Both the ventilation system type and hot wall surface temperature did not influence occupants’ overall thermal perceptions, but their local thermal sensation and skin temperature. The results suggest that the impacts of ventilation system type and hot wall surface temperature on occupants’ local thermal response should be considered during the design of a radiant ceiling cooling system combined with a mechanical ventilation system.