The United States is one of the largest markets in the world for air-conditioning and refrigeration equipment, and was one of the first countries to sign the Montreal Protocol and complies with its obligations through a U.S. national law called the U.S. Clean Air Act of 1990. Phaseout of CFCs in the U.S. is well underway and manufacturers, in compliance with the law, will meet or exceed the requirements set forth in the Montreal Protocol. HCFC-22 is the most widely used refrigerant in the U.S. This is due to the proliferation of residential and small commercial unitary air-conditioning equipment which relies almost exclusively on HCFC-22. It is obvious that the phaseout of the production of HCFC-22, currently scheduled for the year 2020, will have a significant impact on the United States. The HCFC-22 Alternative Refrigerants Evaluation Program (AREP) was established by the Air-Conditioning and Refrigeration Institute (ART) to assist manufacturers in obtaining performance data on a multitude of HCFC-22 and R-502 alternatives. Several alternatives are found to perform almost as well, and sometimes better than the baseline refrigerant. No single alternative emerged as an universal replacement for all applications.