The benefit of the exhausted ventilation air recovery equipment depends not only on the equipment design; it depends on the ventilation system's work mode, heal gains and heal losses ratio too. When the outdoor air temperature exceeds certain limit characteristic for every premise, recovered heat compensates heal demand. Maximum efficiency of heat recovery becomes not indispensable. If the internal temperature continues to rise then the heat demand is lessened till it becomes equal zero and finally the heating of supplied air is switched off. Thus, mean annual heat recovery efficiency is less then technically possible one. The 20% difference was found between nominal efficiency and the real year heal recovery efficiency. The paper is based on the measurements carried out in 60 thous. m3 supermarket hall with run-around loop heat recovery equipment, it's use efficiency was considered as well.