Thanks for the reference but I couldn't find any info on 1 phase motor efficiency. Instead, they seem to consistently say "single phase motors are not required to meet EPAct efficiencies".
I would like to know the relative efficiency of a 5 HP single phase vs. a 3 phase induction motor. The application is an air conditioning compressor (hermetically sealed motor). The same question would apply to a quirrel cage fan motor 1 HP.