Abstract: With the energy efficiency upgrade of AHRI 210/240 in the United States, the calculation method of heating seasonal performance factor (HSPF2) of variable frequency air conditioners focuses more on the medium and low temperature conditions. Through the analysis on the calculation method of HSPF2 and experimental data, it is found that under the same configuration, the HSPF2 is significantly lower compared with the original heating seasonal performance factor (HSPF). The HSPF2_IV corresponding to the climate zone IV decreases by 8.0% on average, and the HSPF2_V corresponding to the zone V decreases by 17.2% on average. The COP under medium and low temperature conditions (H2_V, H3₂, H4₂) has a large proportion of influence on HSPF2. In product design, increasing compressor capacity, using efficient compressor and motor, optimizing heat exchanger structure and other solutions can be considered to improve the seasonal performance factor.

Key words: Variable frequency air conditioner, Heating seasonal performance factor, AHRI 210/240