This paper describes a refrigeration system using a natural refrigerant that has been developed to reduce significantly both direct and indirect greenhouse gas emissions. The new system uses both R-404A and CO 2 (R-744) as refrigerants. The new system has very low global warming potential compared with conventional HFC systems which reduces significantly direct emissions. Indirect emissions are also much reduced as the system efficiency is much greater than achieved using conventional HFC refrigeration. Copyright , Manchester University Press.