Thermal comfort and IAQ assessment of under-floor air distribution system integrated with personalized ventilation in hot and humid climate

The potential for improving occupants' thermal comfort with personalized ventilation (PV) system combined with under-floor air distribution (UFAD) system was explored through human response study. The hypothesis was that cold draught at feet can be reduced when relatively warm air is supplied by UFAD system and uncomfortable sensation as "warm head" can be reduced by the PV system providing cool and fresh outdoor air at the facial level.

A study with 30 human subjects was conducted in a Field Environmental Chamber. The chamber was served by two dedicated systems a primary air handling unit (AHU) for 100% outdoor air that is supplied through the PV air terminal devices and a secondary AHU for 100% recirculated air that is supplied through UFAD outlets.

Responses of the subjects to the PV-UFAD system were collected at various room air and PV air temperature combinations. The analyses of the results obtained reveal improved acceptability of perceived air quality and improved thermal sensation with PV-UFAD in comparison with the reference case of UFAD alone or mixing ventilation with ceiling supply diffuser.

The local thermal sensation at the feet was also improved when warmer UFAD supply air temperature was adopted in the PV-UFAD system.