Numerical investigation of local thermal discomfort in offices with displacement ventilation

Local thermal discomfort in offices with displacement ventilation is investigated using computational fluid dynamics. The standard κ-ϵ turbulence model is used for the prediction of indoor air flow patterns, temperature and moisture distributions, taking account of heat transfer by conduction, convection and radiation. The thermal comfort level and draught risk are predicted by incorporating Fanger's comfort equations in the airflow model. It has been found that for sedentary occupants with summer clothing common complaints of discomfort in offices ventilated with displacement systems result more often from an unsatisfactory thermal sensation level than from draught alone. It is shown that thermal discomfort in the displacement-ventilated offices can be avoided by optimizing the supply air velocity and temperature. It is also shown that optimal supply air conditions of a displacement system depend on the distance between the occupant and air diffuser.