Experimental comparison of three indoor thermal environment control methods: diffuse ceiling ventilation, chilled beam system and chilled ceiling combined with mixing ventilation

Thermal environments created by diffuse ceiling ventilation (DCV), chilled beam system (CB) and chilled ceiling with mixing ventilation (CCMV) were compared at different heat loads. Experiments were carried out in two test rooms (4.1 x 4.2 x 2.9 m3 and 5.5 x 3.8 x 3.2 m3, L x W x H). A double office layout where workstations were located in the perimeter area was investigated. The heat load was increased from a usual level of 38-40 W/floor-m2 to a peak load level of 57-64 W/floor-m2. Air temperature in the occupied zone was kept at 26 ± 0.5°C. Air velocity and temperature were measured with omnidirectional anemometers. Mean air speed, draught rate and temperature differences were all low at the usual load and increased slightly at peak load. The CB system produced more locations with draught rates higher than 10% than the CCMV or DCV systems. Thus, the study suggests using radiant systems with air distribution to reduce draught discomfort in the modern indoor environments.