We experimentally investigated the phenomena of frost retardation in terms of the heat exchanger fins with various water contact angles under normal air-source heat-pump operating conditions. We first introduced a new experimental method using a luminance meter, which measured the light intensity from the surface, and determined the phase-change time, for quantitatively defining the frost stages. The phenomena of frost retardation was analyzed for 10 samples with different water contact angles (75 degrees-160 degrees) at different refrigerant temperatures. When the refrigerant temperature was -10 degrees C or -12 degrees C, the effect of frost retardation increased remarkably with superhydrophobic surfaces. However, when the refrigerant temperature was -8 degrees C, the effect of superhydrophobicity diminished at water contact angles greater than 150 degrees. (C) 2015 Elsevier Ltd. All rights reserved.