In the air-conditioning field there are compressors and combinations of compressors with cylinder unloading which will reduce the pumping rate during Part Load Operation. The information presented herein provides a method for using compressor performance data, standard performance data as provided by the compressor manufacturer, and putting that information into a form which will clearly show the required combinations for greatest energy saving. Air-conditioning load requirements change because of seasonal temperature changes. It is the purpose of this writing to explore the brake horsepower (BHP) per tons refrigeration (T.R.) in systems using large reciprocating compressors in combinations of one or more at reduced capacity by means of cylinder unloading.