Representative data obtained by industry according to DOE test procedures were analyzed to determine the expected impact of frosting/defrosting and cycling on the heating seasonal performance factor (HSPF). The study is made by a simple computation of the HSPF, neglecting the cyclic losses and/or the losses because of frosting/defrosting.

For the representative data presented the effects of neglecting frosting/defrosting in determining the HSPF are noted to be quite small, less than what would be expected based on the limited field data available in the literature. The losses due to cycling effects are also noted to be somewhat lower than expected, based on some of the published field data, but in agreement with the estimates of losses based on other field data.