The complexity and many assumptions used in the procedures to calculate air-source heat pump seasonal energy efficiency ratio (SEER) and heating seasonal performance factor (HSPF) make it difficult to compare energy use with equipment rated under different standards. SEER and HSPF are not indicators for demand since they are seasonal values, and performance at severe conditions is not heavily weighted. The ratings for ground-source heat pumps calculated performance at a single fluid temperature (32°F) for heating coefficient of performance (COP) and a second for cooling EER (77°F). These ratings are not seasonal and reflect temperatures for an assumed location and ground heat exchanger type, and are not ideal indicators of energy use