In this paper, Eurovent puts forward a simplified and easy to apply method for calculating the power consumption of the fans and the SFP_int corrected due to internal leakages occurring in the bidirectional NRVUs with heat recovery (in particular with rotary heat exchangers). The method is based on OACF and EATR factors. Eurovent members believe that the implementation of this method in the revised Regulation 1253/2014 would significantly contribute to the effective improvement in the energy efficiency of NRVUs and IAQ.