R-404A has been the global industry standard HFC refrigerant for commercial refrigeration in both small and large systems. Due to the high global warming potential of R-404A however (AR4 100 year GWP = 3922), interest is growing to identify low GWP alternatives which match R-404A performance. The new low GWP refrigerant HFO-1234yf (100 year GWP = 4) has been found to be a suitable component in mixtures which can be formulated to match R-404A performance while reducing GWP. Two approaches have been investigated. The first is to develop the lowest GWP R-404A alternative possible (GWP c.1400) while maintaining nonflammability. This is desirable for large supermarket systems and for retrofit of existing R-404A systems in the field which were designed for nonflammable refrigerants. The second approach is to drive to the lowest GWP (e.g. c. 250), but with mild flammability which meets ASHRAE A2L classification. This could be suitable for systems where a small degree of flammability may be allowed with smaller refrigerant charge sizes based on industry codes and standards. These two approaches will be evaluated by thermodynamic cycle analysis and through experimental testing in an R-404A self contained freezer. Several parameters will be measured compared to an R-404A baseline, including energy consumption, pressures and temperatures and mass flow rate.