Sick building syndrome: ventilation aspects.

Many occupants of a Swedish office building reported symptoms typical of sick building syndrome (SBS). Tests showed that the supply airflows were inadequate, but there was poor air movement in the rooms. Much of the supply air never reached the occupants but went direct to the exhaust system. Reducing the temperature of the supply air improved its dispersion. Instead of rising, the air sank towards the floor and then circulated through the entire room. Computer simulations using computational fluid dynamics (CFD) techniques confirmed these results and demonstrated the importance of considering air movements as well as supply airflow rates. When CFD was used to model the effects of introducing displacement ventilation, improved air movements were again observed. The results demonstrated that CFD is an effective tool in determining suitable parameters for the ventilation air to achieve good air movements. Moreover the work showed that CFD is a useful method to evaluate and deal with ventilation problems connected to SBS, and should be used at the design stage to construct ventilation systems that will provide good air quality.