Numerical assessment of thermal comfort and air quality in an office with displacement ventilation.

Computational fluid dynamics has been used for assessing the thermal comfort and air quality in an office ventilated with a displacement system for a range of supply air conditions. Thermal comfort is predicted by incorporating Fanger's comfort equations in the airflow model. Indoor air quality is assessed according to the predicted contaminant concentration and local mean age of air. The performance of the displacement ventilation system is then evaluated based on the predicted thermal comfort and indoor air quality. It is shown that discomfort in offices with displacement ventilation results more often from unsatisfactory thermal sensation than from draught. It is also shown that optimal supply air conditions of a displacement system depend on the relative position between the air diffuser and occupant. It has been found that increasing the air flow rate improves indoor air quality but may result in local thermal discomfort.