Computational fluid dynamics (CFO) was used in a study of the air flow characteristics in the occupied building zone. Correlation equations between the mean air speeds and the percentage dissatisfied with the macroscopic flow numbers were derived. Ten macroscopic flow numbers including the total ventilation rate, the air change rate, ventilation rate, air diffusion performance index, modified jet momentum number, two new flow numbers and three expressions of jet momentum ratio were investigated.

The calculation of airflows is of great importance for detailed building thermal simulation computer codes, these airflows most frequently constituting an important thermal coupling between the building and the outside on one hand, and the different thermal zones on the other. The driving effects of air movement, which are the wind and the thermal buoyancy, are briefly outlined and we look closely at their coupling in the case of buildings, by exploring the difficulties associated with large openings.