A simplified proxy model based on a well-mixed batch adsorber for vacuum swing adsorption (VSA) based CO2 capture from dry postcombustion flue gas is presented. A graphical representation of the model output allows for the rationalization of broad trends of process performance. The results of the simplified model are compared with a detailed VSA model that takes into account mass and heat transfer, column pressure drop, and column switching, in order to understand its potential and limitations. A new classification metric to identify whether an adsorbent can produce CO2 purity and recovery values that meet current U.S. Department of Energy (US-DOE) targets for postcombustion CO2 capture and to calculate the corresponding parasitic energy is developed. The model, which can be evaluated within a few seconds, showed a classification Matthew correlation coefficient of 0.76 compared to 0.39, the best offered by any traditional metric. The model was also able to predict the energy consumption within 15% accuracy of the detailed model for 83% of the adsorbents studied. The developed metric and the correlation are then used to screen the NIST/ARPA-E database to identify promising adsorbents for CO2 capture applications.