The purpose of this Recommendation is to provide a generic methodology for estimating energy consumption of air filters for general ventilation under actual operating conditions, taking into consideration: wide range of airflow rate, actual filter dimensions, approach to the filter change (condition based and time based method), actual operating time and actual fan efficiency. The document is built on the methodology defined in Eurovent 4/21 and implements the ISO 16890 classification, as well as its testing methods. This Recommendation, together with Eurovent 4/21 and Eurovent 4/25, forms a set of Eurovent documents for evaluation of energy consumption and energy efficiency of air filters. The differences between the scope of respective Recommendations are the following: Eurovent 4/21 is an integral Recommendation for energy rating and filter performance comparison at standard reference conditions as a basis for the certification programme and Eurovent 4/25 is a simplified version of this Recommendation to propose a consistent evaluation of energy consumption of air filters in the revised Regulation (EU) 1253/2014. This is the first edition of the document and it is the English version.