Field measurements of characteristics of turbulent air flow in the occupied zone of ventilated spaces.

Characteristics of the air velocity were measured at 500 points in the occupied zone of 20 typically ventilated spaces. A relationship between the mean velocity and the standard deviation was found at four heights above the floor. The turbulence intensity varied from 10 to 70% at ankle level (0.1 m) and from 20 to 55% at head level. This is similar to the experimental conditions under which the draught chart by Fanger and Christensen was established. The impact of turbulence intensity on the draught sensation should be studied by exposing subjects to air flows with constant mean velocities and turbulence intensity varying up to 70%.