The paper reviews the refrigerant/freezer (RF) design and refrigerant selection process that is necessary to design an energy efficient RF that does not use fully halogenated chlorofluorocarbons (CFCs). EPA is interested in phasing out CFCs in RFs to minimize stratospheric ozone depletion while simultaneously making RFs more energy efficient to minimize global warming. Dual-circuit RFs have been shown to have a theoretical advantage over single-evaporator RFs, since evaporation may occur at a higher pressure in the fresh food loop of a dual-circuit system. Single refrigerants were simulated in a computer model to determine the optimum pure refrigerant in each of the two separate freezer and fresh food loops. R-152a was determined to be the optimum single refrigerant in the freezer, and R-142b and R-152a were determined to be the optimum single refrigerants in the fresh food section. With the assumptions made, theoretical energy savings of up to 23% are possible. The ideal RF should be safe, energy efficient, and inexpensive.