Thermal comfort in ventilated spaces depends mainly on air temperature, air speed and turbulence intensity. The indices for assessing thermal comfort, such as PMV and Draught rating, are based on measurements of the time-averaged mean air speed with omnidirectional hot sphere sensors. At present, thermal comfort is often estimated computationally by CFD-simulations. The mean air speed is not directly obtained from CFD-simulation and therefore the velocity vector magnitude is usually used instead. Since it is smaller than the mean air speed, this method may lead to underestimation of thermal discomfort. A correction method has been earlier proposed for calculating thermal comfort from CFD-simulation results. In this study, the correction method was implemented in CFD-software. Air speed and draught rating values were calculated for two simulated case examples and the effect of the turbulence correction was studied. The correction was found to be significant in room areas with high turbulence intensities.