Energy performance index of air distribution: Thermal utilization effectiveness

•Thermal Utilization Effectiveness is introduced and verified as the energy performance index of air distribution.•Energy Utilization Coefficient ignores relative contributions of occupied and unoccupied zones to energy performance.•Effectiveness of Heat Removal cannot qualitatively distinguish the energy performance of air distribution.•Heat Removal Efficiency cannot quantitatively distinguish the energy performance of air distribution.•Thermal Utilization Effectiveness addresses the drawbacks of the above three energy performance indices.