Extending effective draft temperature to cover full range of air velocity

The effective draft temperature (EDT) is widely used for the evaluation of air distribution performance regarding thermal comfort. The applicability of the conventional EDT is limited to the air velocity below 0.35 m/s. However, the air velocity can be elevated to as high as 0.80 m/s for energy saving. This study extends the EDT to cover the full range of air velocity. The transfer coefficient of air velocity to air temperature of the proposed extended EDT is quantified based on the cooling effect of the air movement (calculated from the standard effective temperature), and the reference state and upper and lower boundaries of the proposed extended EDT are quantified based on the thermal neutrality and the upper and lower boundaries of thermal comfort respectively (calculated from the Predicted Mean Vote). Experiments in a stratum-ventilated office with elevated air velocity are used to validate the proposed extended EDT. Results show that the conventional EDT has an average accuracy rate of 69.6%. The existing extended EDT (with an average accuracy rate of 71.7%) outperforms the conventional EDT by 3.1% and the proposed extended EDT (with an average accuracy rate of 97.8%) outperforms the conventional EDT by 40.6%. The proposed extended EDT according to Categories I–III of thermal comfort under both cooling and heating modes is tabulated for convenient applications in practice.