Effect of humidity and small air movement on thermal comfort under a radiant cooling ceiling by subjective experiments

Radiant air-conditioning systems are expected to be more comfortable and superior energy-saving systems than convective air conditioning ones generally used. There are some studies on radiant cooling systems. However, they were seldom put to practical use because of dew point problem in Japan. The objective of this study is to investigate the thermal comfort of local parts of the body and the whole body, in particular, including the effects of humidity (45% rh, 65% rh, 85% rh) and small air movements, by subjective experiments under a radiant cooling system. The experiments have been performed by using radiant cooling panels in a climate chamber. Subjects were seated on a chair under the radiant cooling panels, and voted their thermal sensation and comfortable sensation. The following results were obtained. Even in the radiant cooling system, the influence of humidity and small air movement on thermal sensation votes of the whole body could be correctly estimated by using a standard new effective temperature (SET*) within one scale error of thermal sensation. Small air movement with the radiant cooling system had a possibility of improving the comfortable sensation votes in the radiant cooling.