Frosting inside heat/energy exchangers are common especially in cold climates and result a significant decrease in the performance of the exchangers. Using experimental effectiveness data from a previous research [1] and ambient temperature/enthalpy duration curves the effect of preheating the outdoor air and bypassing the outdoor airflow (supply side closing) techniques on annual heating energy consumption of ventilation are predicted in three different weather European locations (in Helsinki in Finland as Cold climate, in Krakow in Poland as North Temperate climate and in Palermo in Italy as Mediterranean climate). The results are presented separately based on the analyzed techniques: supply side closing, pre-heating and frosting effect ignoring. The results show the outdoor air preheating technique results higher energy saved than the supply side closing and if the indoor air quality requirements are lower, then using a sensible heat recovery unit is suitable for heat recovery and the investment cost is lower. (C) 2015 Elsevier B.V. All rights reserved.