All three parts of this work corroborated a massive dependence of the adsorption energies on the choice of dc-XC functional, with quantitative deviations frequently amounting to several 10 per cent in relative terms. These variations are essentially independent of the choice of basis sets or the optimisation strategy. Hence, it is clear that any study that is aimed at an at least semi-quantitative prediction of adsorption energies for organic contaminants (or other sizeable organic molecules) in zeolites will have to pay considerable attention to the use of an appropriate DFT approach. On the other hand, the results of Part 1 showed that qualitative trends are not strongly affected by the dc-XC functional. Therefore, DFT-based investigations that are primarily aimed at the identification of zeolite-guest combinations exhibiting strong interaction should be fairly insensitive to the choice of approach. Although the occurrence of some outliers in Figure serves as a reminder that caution must be exercised in individual cases, the overall findings indicate that the identification of zeolite adsorbents having a high affinity towards a given contaminant should, in the majority of cases, not depend strongly on the dc-XC functional, at least among the 13 functionals tested.