Heat pump system performance in Northern climates

Single-value ratings for heat pumps and air conditioners have become industry standards and are widely used by consumers, designers, and program managers for equipment selection and prediction of performance. On the heating side, the standard rating is the heating seasonal performance factor (HSPF), and on the cooling side the standard rating is the seasonal equipment efficiency ratio (SEER). These values are determined under set conditions. However, the actual performance of the equipment depends on the climate in which it is being used. Furthermore, the overall energy use can be greatly impacted by factors such as control strategy and duct losses. This paper presents the results of computer modeling using the bin method to estimate the impact of climate, certain common control strategies, sizing approaches, and duct losses on the HSPF of heat pumps in two climates in the northwest United States. Comparisons with field data and observations show impacts on heat pump performance consistent with modeling results.