Effects of different cooling principles on thermal sensation and physiological responses

Applying low exergy cooling concepts in the built environment allows reduction of use of high quality energy sources. Non-uniform thermal conditions, which may occur due to application of lowex systems, can result in discomfort. Two different cooling principles were studied: passive (through convection in terms of increased air velocities) and active cooling (through convection or radiation). Furthermore, two different ventilation techniques were included: mixing and displacement ventilation. Ten male subjects (age: 20-29) were exposed to six different cases: (1) PC-C-M; passive cooling through mixing ventilation, (2) AC-C-M; active cooling through convection by mixing ventilation, (3) AC-C-D; active cooling through convection by displacement ventilation, (4) AC-R-M-C; active cooling through radiation by the ceiling and mixing ventilation, (5) AC-R-M-F; active cooling through radiation by the floor and mixing ventilation, and (6) AC-R-D-F; active cooling through radiation by the floor and displacement ventilation. Though all cases were designed at PMV approximate to 0, subjective data indicate significant differences between the cases. For the prediction of thermal sensation and thermal comfort under non-uniform conditions, the operative temperature only is not sufficient. Combined local factors play an important role in the comfort assessment. Furthermore, non-uniform environments, as case 6, can achieve a comparable or even a more comfortable assessment compared to uniform environments. (c) 2013 Elsevier B.V. All rights reserved.