Chlorofluorocarbons (CFCs) are the class of refrigerants that contribute the most to ozone depletion potential (ODP). Ozone depletion potential is a measure of how much a substance can damage the ozone layer in the stratosphere, which protects life on Earth from harmful ultraviolet radiation. CFCs are synthetic chemicals that contain chlorine, fluorine, and carbon atoms. They were widely used as refrigerants, aerosol propellants, solvents, and foam blowing agents until they were phased out by the Montreal Protocol due to their high ODP. The LEED Green Associate Candidate Handbook states that one of the strategies for achieving energy and atmosphere efficiency is to “eliminate chlorofluorocarbons (CFCs) in new building HVAC&R systems†[1, p. 15]. References: LEED Green Associate Candidate Handbook, [Ozone Depletion Potential | U.S. Environmental Protection Agency]