The History of Refrigerants, and a Glimpse at Their Future
Several proposed changes were submitted for the International Building, Fire and Mechanical Codes during the 2021 Group A code cycle. These proposed changes would permit the usage of A2L refrigerants, continuing the nearly 200-year history of refrigerant evolution.
By the 1930s, safety issues involving many early refrigerants emerged, leading to the invention of synthetic safety refrigerants (chlorofluorocarbons or CFCs), along with the development of partially chlorinated refrigerants (hydrochlorofluorocarbons, or HCFCs. By the 1970s, it was discovered that these refrigerants caused the ozone layer to breakdown, which could result in harm to our health and to our environment. In 1987, Canadian diplomats forged the Montreal Protocol, a treaty that called for drastic global phasedowns in the production of CFCs, which have high ozone-depleting potential. The Protocol went into effect in 1989, allowing hydrofluorocarbons or HFCs to take center-stage.
While HFCs have an ozone-depletion potential of zero, they are still potent greenhouse gases with medium-to-high global warming potential (GWP). The usage of HFCs has been scrutinized and they are regulated under the 2019 Kigali Amendment to the Montreal Protocol because of their contributions to climate change.
While refrigerant systems are not intentionally vented to the atmosphere, a leaky system can have an immense impact on global warming. In late 2021, the United States Environmental Protection Agency (EPA) issued a rule under the American Innovation & Manufacturing (AIM) Act that mandates an 85 percent economy-wide phasedown in HFC refrigerants over the next 15 years. The phasedown is expected to avoid 900 million metric tons of CO2 emissions by 2035, and avoid up to 0.5 degrees Celsius of global warming by 2100.
The phasedown of HFCs has ramped up a growing acceptance of the use of A2L refrigerants as a substitute. The A2L subgroup are a class of refrigerants that have lower toxicity and flammability compared to other classifications, making it the second-safest refrigerant category. A2Ls also have a significantly lower GWP than A1-class HFCs. Globally, A2Ls have been used safely for years, and as of 2018, more than 68 million air conditioners using A2L refrigerants have been installed around the world. Besides this, the EPA has adopted a final rule accepting six refrigerant alternatives for use in new residential and light commercial air conditioners and heat pumps that meet the requirements in UL 60335-2-40 for air conditioning equipment. Each lower GWP alternative — R–32, R–452B, R–454A, R–454B, R–454C and R–457A — is classified by ASHRAE as A2L (mildly flammable).
Since A2Ls are new to the United States and have different flammability characteristics, safety, training, and building code updates are extremely important.
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