Air conditioners use refrigerants to carry heat between the indoor and outdoor units. In the late 1970s, it was discovered that CFC and HCFC fluorocarbon gases, which were the most common refrigerants of that time, deplete the ozone layer if released into the atmosphere. Since then, Daikin, as a manufacturer of fluorocarbon gas, has been working to find refrigerants that exert as little impact as possible on the environment. Let's look at air conditioner refrigerants as they relate to global warming and ozone layer depletion.

Major Substances Used as Refrigerants
■ CFC
Chemical compounds consist of chlorine, fluorine, and carbon. Widely used in the past as refrigerant for air conditioners. CFCs were found to deplete the ozone layer and developed countries stopped manufacturing them in 1995. CFCs are greenhouse gases with a global warming potential three to 10 times that of HFCs.
■ HCFC
Chemical compounds consist of hydrogen, chlorine, fluorine, and carbon. Used to substitute for CFCs, HCFCs have an ozone depletion potential just one-twentieth that of CFCs. Developed countries will stop manufacturing HCFCs in 2020. The global warming potential is about the same as HFCs.
■ HFC
Chemical compounds consist of hydrogen, fluorine, and carbon. A CFC substitute (hydro-fluorocarbon). With an ozone depletion potential of zero, HFCs are the best refrigerant for protecting the ozone layer. HFCs are currently in the process of being substituted for HCFCs. However, HFCs are designated in the Kyoto Protocol as a greenhouse gas whose emission must be reduced. As well, like CFCs and HCFCs, the release of HFCs into the atmosphere is forbidden under the Fluorocarbons Recovery and Destruction Law (Japan).
■ Natural Refrigerants
Substances existing in the natural world and having refrigerant characteristics. Examples are ammonia, hydro carbon (propane), and CO2.