What is meant by the 'energy performance' and 'energy classification' of filters?

In Annex X, the information requirements for NRVUs require:

(p) energy performance, preferably energy classification, of the filters (declared information about the calculated annual energy consumption);

The suggested method to provide this information requirement is the declaration of the filter classification (efficiency) determined according to Annex IX.

_{Disclaimer: Please note that the European Commission cannot provide a legally binding interpretation of the EU legislation, as this is the sole competence of the European Court of Justice. Any remarks from the European Commission services are without prejudice to the position the Commission might take should related cases arise in a procedure before the Court of Justice.}