Mechanism for advancing air distribution: Matching zonal priorities with cascade utilization of air potential

Advancing air distribution is one of the core tasks for developing low-carbon and healthy building environments. However, the mechanism for advancing air distribution is unclear. This study reveals and justifies the mechanism for advancing air distribution, i.e., the air potential should be maximally used, which indicates the air potential is used cascadingly to match the zonal priorities. Regarding thermal comfort, the supply air should be used sequentially to condition the breathing, lower, and upper zones, which is described quantitatively by the Matching of Thermal Potential, a newly proposed index. The larger the Matching of Thermal Potential, the higher the energy efficiency. This is verified by the coefficient of determination (R²) of greater than 0.95 for the case studies on mixing ventilation, displacement ventilation, stratum ventilation, and interactive cascade ventilation. Moreover, due to the coupled heat and mass transfer, a higher Matching of Thermal Potential leads to a younger mean age of air in the breathing zone. According to the mechanism, a novel air distribution strategy, i.e., graded ventilation, is proposed as an example. It reduces energy consumption by 8.4% - 53.5% and the mean age of air in the breathing zone by 7.8% - 23.4% under different thermal conditions. The revealed mechanism contributes to advancing air distribution for improved energy efficiency and inhaled air quality while providing thermal comfort.