Comparison between thermal environmental stabilities of radiant and convective air-conditioning systems

Radiant air-conditioning systems and floor-supply displacement heating, ventilation, and air conditioning (HVAC) systems have recently attracted considerable attention. However, such systems have not yet seen widespread use because the degree to which they increase thermal comfort is not clear. In this study, the authors measured the planar thermal deviation during summer in four offices: two offices employed a radiant air-conditioning system and a floor-supply displacement HVAC system, and the other two offices employed convective air-conditioning systems. The results showed that the convective air-conditioning system caused wide temporal and spatial variations in the thermal environment. Therefore, in buildings with convective air-conditioning systems, even if the planar average thermal environment was categorized as comfortable, it was presumed that workers who were sensitive to cold or heat complained of discomfort more often than those in buildings with radiant air-conditioning systems because the probability of workers sitting in cold or hot spots increased.