Thermal comfort study on vertical air temperature gradient with displacement ventilation system in the tropics

The objective of this study is to explore the influence of vertical air temperature gradient and room air temperature (at 0.6 m height) on overall and local thermal comfort of 30 tropically acclimatized subjects in a room served by Displacement Ventilation (DV) system. These 15 males and 15 females were engaged in sedentary office work for a period of 3 hours. The subjects were exposed to 3 levels of vertical air temperature gradient, nominally 1, 3 & 5 K/m, between 0.1 and 1.1 m heights and 3) room air temperatures, 20, 23 & 26 degrees C, at the height of 0.6 m. The main findings of this study are that temperature gradient had different influence on thermal comfort at different room temperatures. Room temperature had greater influence on thermal comfort than temperature gradient. Tropically acclimatized subjects could tolerate temperature gradient of 5 K/m at room temperature of 26 degrees C.