Effects of velocity variations in ventilated rooms on comfort, affect and cognitive performance

96 human subjects (18 years age students from a Swedish high school) were submitted in an experimental room furnished as a classroom to different air flows issued from different ventilation systems : displacement with constant air flow rate, alternating between displacement (floor diffusers) and mixing ventilation (ceiling diffusers) with constant flow rate, mixing ventilation with varying flow rate, displacement with constant flow rate and with ceiling fans to generate air motions alternatively on and off. Activuty of the subjects was composed of tasks allowing to estimate their intellectual performance. A questionnaire also concerned their perception of comfort. Air velocity variations did not affect thermal comfort but had a positive effect on perceived indoor air quality and on cognitive performance.