A refrigeration system is disclosed. The system includes a compressor, a condenser, an expansion device, and an evaporator fluidly connected to form a refrigeration circuit. A refrigerant composition including an environmentally-suitable chiller refrigerant that has a 100 year direct global warming potential (GWP) of less than 150 is included. The refrigerant composition includes a mixture including R-1336mzz-(Z) and R-1130-(E), wherein an amount of R-1336mzz-(Z) in the mixture is in a range from at or about 69% by weight to at or about 81% by weight, and an amount of R-1130-(E) in the mixture is in a range from at or about 31% by weight to at or about 19% by weight.