Ventilation Performance Index of Thermal Comfort for Stratum Ventilation: Extending Effective Draft Temperature to Cover Full Range of Air Velocity

The conventional effective draft temperature (EDT) is commonly used to assess air distribution performance regarding thermal comfort. However, its applicability is limited to air velocities below 0.35 m/s. To accommodate higher air velocities of stratum ventilation for energy saving, this chapter proposes an extension EDT to cover the full range of air velocity. The transfer coefficient of air velocity to air temperature in the proposed extended EDT is determined based on the cooling effect of air movement, calculated using the standard effective temperature. The reference state, upper and lower boundaries of the proposed extended EDT are quantified based on thermal neutrality, the upper and lower boundaries of thermal comfort. Experimental investigations are conducted in a stratum-ventilated office to validate the proposed extended EDT, respectively. Results demonstrate that the conventional EDT achieves an average accuracy rate of 69.6%. The existing extended EDT outperforms the conventional EDT with an average accuracy rate of 71.7%. The proposed extended EDT exhibits significant improvement, surpassing the conventional EDT by 40.6% with an average accuracy rate of 97.8%. To facilitate practical applications, the proposed extended EDT is tabulated according to Categories I to III of thermal comfort under cooling and heating modes.