Abstract:Abstract:To evaluate the uncertainty of measurement of energy efficiency of the external rotor fan, an air conditioning outer rotor of model №5.6 was selected to evaluate the uncertainty of energy efficiency measurement. A type of outlet side test wind chamber energy efficiency measuring device was used. The results show that the relative extended uncertainty of the energy efficiency measurement results of the external rotor fan should be greater than 1.2% (k=2), providing the measuring accuracy of the energy efficiency of the centrifugal fan for the legal metrological verification institutions and providing theoretical support for the realization of the fan market specification.