Most common current refrigerants and their alternatives
After chlorofluorocarbons (CFCs) were partially banned in the 1980s due to their ozone-depleting properties and finally banned completely in the 1990s, Germany decided to only allow non-ozone-depleting refrigerants to be used in new systems.
These systems now widely use F-gases (hydrofluorocarbons, or HFCs). However, several of these refrigerants are harmful to the climate due to a strong greenhouse effect. R-410a, which is widely used in stationary air-conditioning systems, has a GWP (global warming potential) of 1,725 and is extremely harmful to the climate; it must not be allowed to leak into the environment under any circumstances.
R-404a, R-507 as well as R-134a, which is mainly used in vehicles, also have high GWP values (3,920, 3,850 and 1,430, respectively). R-134a was banned years ago from air-conditioning systems in new passenger cars since it escapes relatively easily from those types of systems.
R-1234yf is considered a good alternative to R-134a since it has a low GWP of 4 and several properties comparable to R-134a. However, the hydrofluoroolefin (HFO) used in R-1234yf (2,3,3,3-tetrafluoropropene) is mildly flammable.