Influence of internal and external air leakages on the real performance of an air handling unit with two-stage heat recovery

Abstract The purpose of this study is to evaluate the influence of internal and external air leakages, which appears to be small but actually leads to a serious discrepancy between the theoretical and real performance of air handling units with two-stage heat recovery of the exhaust air. The results show that the overall efficiency of the air handling unit is up to 12.4% lower than theoretical for Class 3 equipment. With increasing airtightness, the efficiency of the AHU, expressed with COP, can be increased by about 3.2% as the class increases by one level.