Refrigerants used in HVAC systems, refrigeration units, and heat pumps to absorb and release heat can pose a significant environmental threat. In line with the sustainability goals of the built environment, it is essential to understand two key environmental metrics associated with refrigerants: Ozone Depletion Potential (ODP) and Global Warming Potential (GWP).
In this writing, we’ll mention these metrics.
Global Warming Potential (GWP)
It measures how much heat a greenhouse gas (GHG) traps in the atmosphere over a specific period compared to carbon dioxide (CO2) which has a GWP of 1. If they leak during the installation, use, maintenance or disposal, they trap much more heat in the atmosphere than the CO2. For instance, Methane (CH4) has a GWP of around 28-36, and meaning it’s more effective at trapping heat than CO2.
Ozone Depletion Potential (ODP)
It measures how much a substance can degrade the ozone layer, compared to CFC-11 which has an ODP of 1. ODP is the key metric by choosing less harmless refrigerant, therefore it should be zero or close to zero.
| Refrigerants | GWP | ODP | Plans | |
| CFCs (chlorofluorocarbons) | Very High | 1 | Phased-out | by 2010 globally (Montreal Protocol, 1987) |
| HCFCs (hydrochlorofluorocarbons) | Moderate | Small | Gradual Phase-out | developed countries by 2020, developing countries by 2030 |
| HFCs (hydrofluorocarbons) | High | Zero | Being replaced | reduction by 2047 (Kigali Amendment) |
| HFOs & blends | Low | Zero | Newer sustianable alternatives | |
| Naturals & HCs | Extremely Low | Zero | Eco-friendly options |
When selecting refrigerants, it is essential to choose options with zero Ozone Depletion Potential (ODP) and a Global Warming Potential (GWP) as close to zero as possible. To minimize the environmental impact of substances that contribute to ozone depletion or global warming, various phase-out plans have been legislated. Understanding these phase-out strategies requires close attention to the international environmental protocols and regulations that guide and enforce these efforts.
Montreal Protocol (1987): Its purpose was protecting the ozone layer by phasing out ozone-depleting substances like CFCs and HCFCs. CFCs has completely phased out globally by 2010, and HCFCs should phase out by 2030 for developing countries.
Kigali Amendment to the Montreal Protocol (2016): It adresses climate change by phasing down HFCs with high GWP, and introduces GWP as a new control metric. It aims to reduce HFC use by 85% by 2047.
American Innovation and Manufacturing (AIM) Act (2020): It aligns U.S. with Kigali Amendment goals, by aiming phasedown of HFCs by 85% by 2036.
