Refrigerants used in air conditioners are changing … again. The last round of changes took place between the mid-1990s through 2010, as chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) refrigerants were phased out and largely replaced by hydrofluorocarbons (HFCs). This transition was a global effort under an international treaty known as the Montreal Protocol that addressed the destructive effects these compounds had on the ozone layer. Periodic measurements have confirmed that, since implementing those refrigerant changes, there has been a steady decrease of ozone-depleting substances in the atmosphere. The current round of changes stems from the Kigali agreement to the Montreal Protocol, and it aims to reduce the greenhouse effect of refrigerants.
This article will focus on the class of refrigerants that will replace R-410A, the most commonly used refrigerant in air conditioners and heat pumps installed today. R-410A was the primary replacement for R-22 during the last transition. While not ozone-depleting, R-410A has a higher global warming potential (GWP) than R-22, so its environmental impact rules it out as a long-term refrigerant solution. Similar concerns apply to other refrigerants currently in use for applications involving cooling or refrigeration but are beyond the scope of this article.