Impact of personalized ventilation combined with chilled ceiling on eye irritation symptoms

Personalized ventilation (PV) improves inhaled air quality, because it provides fresh air to each workstation and directly to occupant’s breathing zone. The PV alone can be used for room ventilation when applied in conjunction with ceiling radiant cooling system, which removes sensible heat loads from the space.

Combining PV with chilled ceiling may be an effective way to provide thermal comfort in rooms at air temperature higher than the recommended in the standards upper limit of 26°C (category II), because the operative temperature will be lower. However, combination of high air temperature, elevated air movement toward face and increased radiant cooling may have impact on the eye symptoms.

Twenty four human subjects participated in experiments with PV combined with chilled ceiling system (CCPV) and with mixing ventilation (MV) combined with chilled ceiling (CCMV). In the experiments with PV participants were provided with control of supplied air flow rate and direction. Room air temperature was kept at 26°C and 28°C.

Relative humidity in the chamber was not controlled but was monitored and it varied between 20% and 30% during the experiments. Supplied air temperature (by PV and MV) was 3 K lower than room air temperature. Average supply/return water temperature for chilled ceiling was 15,5/16,8°C at room air temperature of 26°C and 19,5/20,6°C at 28°C.

The total exposure time was 3 h (with 0,5-h. acclimatization period). During the experiment subjects performed typical office tasks at workstations with computers. Exposure included also a higher activity level office work for a period of 25 min outside computer workstations. The influence of the environment on eye symptoms was assessed by subjective votes and objective measurements.

Subjects reported on the eye irritation and the intensity of eye dryness 6 times throughout each experiment. Eye tear film samples were taken at the beginning and the end of the exposure. The blinking rate was analysed in the beginning and at the end of exposures. The preliminary results of the analyses reveal that the environment subjects were exposed to had an impact on their subjective and physiological response.