Every refrigerator and air conditioner contains chemical refrigerants that absorb and release heat to enable chilling. Refrigerants, specifically CFCs and HCFCs, were once culprits in depleting the ozone layer. Thanks to the 1987 Montreal Protocol, they have been phased out. HFCs, the primary replacement, spare the ozone layer, but have 1,000 to 9,000 times greater capacity to warm the atmosphere than carbon dioxide.
In October 2016, officials from more than 170 countries met in Kigali, Rwanda, to negotiate a deal to address this problem. Through an amendment to the Montreal Protocol, the world will phase out HFCs—starting with high-income countries in 2019, then some low-income countries in 2024 and others in 2028. Substitutes are already on the market, including natural refrigerants such as propane and ammonium.
Scientists estimate the Kigali accord will reduce global warming by nearly one degree Fahrenheit. Still, the bank of HFCs will grow substantially before all countries halt their use. Because 90 percent of refrigerant emissions happen at end of life, effective disposal of those currently in circulation is essential. After being carefully removed and stored, refrigerants can be purified for reuse or transformed into other chemicals that do not cause warming.
Montreal Protocol: UNEP. Montreal Protocol on Substances that Deplete the Ozone Layer: Final Act. United Nations Environment Programme, 1987.
ozone layer is beginning to heal: Solomon, Susan, et al. “Emergence of Healing in the Antarctic Ozone Layer.” Science 353, no. 6296 (2016): 269-274.
hydroflourocarbons [vs.] carbon dioxide: Myhre, Gunnar, Drew Shindell, François-Marie Bréon, William Collins, Jan Fuglestvedt, Jianping Huang, Dorothy Koch et al. “Anthropogenic and natural radiative forcing.” In Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, UK, and New York: Cambridge University Press, 2013.
2016…amendment to the Montreal Protocol: Davenport, Coral. “Nations, Fighting Powerful Refrigerant That Warms Planet, Reach Landmark Deal.” New York Times. October 15, 2016; Johnston, Chris, et al. “Climate Change: Global Deal Reached to Limit Use of Hydrofluorocarbons.” The Guardian. October 15, 2016.
John Kerry…“biggest thing we can do”: Davenport, “Landmark Deal.”
reduce…warming…one degree Fahrenheit: Johnston et al, “Global Deal.”
[growth of] air-conditioning…by 2030: Shah, Nihar, Max Wei, Virginie Letschert, and Amol Phadke. Benefits of Leapfrogging to Superefficiency and Low Global Warming Potential Refrigerants in Room Air Conditioning. Lawrence Berkeley National Laboratory, 2015.
emissions…at end of life: Zhao, L., W. Zeng, and Z. Yuan. “Reduction of Potential Greenhouse Gas Emissions of Room Air-Conditioner Refrigerants: A Life Cycle Carbon Footprint Analysis.” Journal of Cleaner Production, 100 (2015): 262–268.
destruction…to reduce emissions: World Bank. Study on Financing the Destruction of Unwanted Ozone-Depleting Substances through the Voluntary Carbon Market. Washington, D.C.: The World Bank, 2010.
air-conditioning in…U.S. homes: HUD. American Housing Survey for the United States: 2009. Washington, D.C.: U.S. Department of Housing and Urban Development and U.S. Department of Commerce, 2011.
in urban Chinese households: Shah et al, Leapfrogging.
Their replacement chemicals, primarily hydrofluorocarbons (HFCs), have minimal deleterious effect on the ozone layer […].
HFC substitutes are already on the market, including natural refrigerants such as propane and ammonia. Carbon dioxide itself can be used in specially designed systems that achieve much higher pressure.
The Kigali accord ensures a step change is coming, and other practices focused on existing stocks could reduce emissions further.
Caption: HFCs are largely innocuous to the ozone layer, but they are one of the most potent greenhouse gases known to humankind.
Revision: Our analysis includes emissions reductions that can be achieved through the management and destruction of refrigerants already in circulation. Over thirty years, containing 87 percent of refrigerants likely to be released could avoid emissions equivalent to 89.7 gigatons of carbon dioxide. Phasing out HFCs per the Kigali accord could avoid additional emissions equivalent to 25 to 78 gigatons of carbon dioxide (not included in the total shown here). The operational costs of refrigerant leak avoidance and destruction are high, resulting in a projected net cost of $903 billion by 2050.
Project Drawdown defines refrigerant management as: controlling leakages of refrigerants from existing appliances through better management practices and recovery, recycling, and destruction of refrigerants at the end of life. This solution replaces conventional refrigerant management practices.
Refrigerants are used as working fluid in commercial refrigeration systems, in household appliances such as air conditioners and refrigerators, in refrigerated containers used for carrying perishable goods, as air conditioning systems onboard cars, trains, aircrafts, and ships, and in industrial cooling systems, etc. There are various classes of refrigerants.  Chlorofluorocarbons (CFCs) are ozone depleting substances and have been phased out under the Montreal Protocol; Hydrochlorofluorocarbons (HCFCs) are also being phased out. Hydrofluorocarbons (HFCs), which do not deplete the ozone, emerged as an alternative to HCFCs and have grown to extensive use. All refrigerants have a high global warming potential, and their release into the environment contributes to global warming. Considering the large impact which the release of refrigerants has on global warming, world leaders have agreed to phase out HFCs and replace them with natural refrigerants with much less warming potential under the Kigali Accord in October, 2016. Refrigerants are emitted into the environment during the production process, from refrigerant banks  due to leakages, and during end-of-life disposal of the appliances.
Measuring the refrigerant management solution requires: generating a total addressable market forecast of the refrigerant gas emissions for the period 2020-2050 (in kilotons of carbon dioxide-equivalent emissions per year), forecasting an adoption of management measures and the resulting decreased emissions from those measures for each year from 2020-2050, and then comparing the difference in emissions from the total market and the adoption scenarios to arrive at the results.
Refrigerant management can be undertaken in five main ways:
(i) Lowering the demand/use of appliances and thereby production of refrigerants.
(ii) Replacing refrigerants with low-warming HFCs/new cooling agents/non-HFC substances.
(iii) Increasing the refrigeration efficiency in appliances, thereby lowering the use of refrigerants.
(iv) Controlling leakages of refrigerants from existing appliances by good management practices.
(v) Ensuring recovery, reclaiming/recycling, and destruction of refrigerants at end of life.
The Drawdown solution models the lasts two options.
Total Addressable Market 
The model uses available projections for the size of refrigerant banks. It then estimates the leakages from these banks using historical leakage rates for various sub-sectors such as commercial, industrial, domestic, and stationary (as opposed to mobile) AC systems. This is the total addressable market.
Adoption of good practices to control leakages is modeled as a part of the solution. The solution also models the accompanying costs from the application of these measures. Additionally, the solution considers the destruction of refrigerants at end of life: some of the refrigerants are recovered and destroyed at this point. The current quantity of refrigerants which are recovered and destroyed is estimated by using the historical data on equipment retirement rates, recovery efficiency, and destruction efficiency. For 2014, this value is estimated to be around 30 kilotons of refrigerant, which is approximately 2.7 percent of the total quantity emitted. This is the current adoption. 
This solution models the potential of capturing a higher portion of this refrigerant stream. Estimates of refrigerant banks in the future are used to calculate the end-of-life banks based on the expected lifetime of the equipment. Thereafter, higher recovery efficiencies are assumed based on the technical feasibility of recovery from various sub-sectors. Assumptions on increased destruction efficiencies are then used to estimate the refrigerant which can be destroyed in the future along with cost implications. The two parts of the solution are then combined to calculate the total impact.
Adoption Scenarios 
Impacts of increased adoption of refrigerant management from 2020-2050 were generated based on three growth scenarios, which were assessed in comparison to a Reference Scenario where the solution’s market share was fixed at the current levels. Descriptions of Drawdown's Plausible, Drawdown, and Optimum Scenarios to come.
In the conventional case, direct emissions from refrigerants which leak during the lifetime and at end of life contribute to global warming. These are dependent on the quantity of refrigerants which are emitted in the environment and their respective global warming potential. For the refrigerant management solution, it is assumed that all emissions are from a standard refrigerant which has a potential of 2326.
Modest amounts of electricity are consumed when refrigerant destruction facilities are operated. This is quantified for the solution as energy, in kilowatt-hours per kilogram.
For financial consideration, Drawdown decided to consider only the operating cost factor for this solution. No direct upfront costs are applicable for control of leakages from appliances (Purohit and Isaksson, 2016). However, there are operational and maintenance costs per unit of refrigerant for adopting these measures. Only costs of collection, recovery, and destruction were used as operational costs per ton of refrigerant. The annual costs multiplied by the estimated emissions avoided give the total costs and the average annual costs per unit of HFC avoided for different years.
The total costs for end of life recovery, removal, and destruction are calculated in a similar way.
The total carbon dioxide-equivalent reductions that can be achieved from 2020-2050 in the Plausible scenario are 89.7 gigatons, with a net operating cost of US$902.8 billion. The Drawdown Scenario optimizes recovery factors and destruction rates, showing a mitigation of 96.5 gigatons from 2020-2050, and the Optimum Scenario also shows a mitigation of 96.5 Gt.
Refrigerant management is difficult to implement as the appliances are distributed. There are weak regulations on controlling leakage of refrigerants, end-of-life recovery, and refrigerant. Further, there are no economic incentives for the recovery of refrigerants. Funding, training, technical, and informational barriers are also some of the limitations for adoption of the solution.
In order to increase adoption, policies and regulations on recycling/management of refrigerants need to be formulated and implemented. Strong regulations such as a complete ban on venting of refrigerants and accountability of refrigerants must be introduced in national legislation. Economic incentives for recovery, recycling, and destruction of refrigerants, such as the issue of carbon credits under the Kyoto protocol, would help increase the adoption in developing countries. Capacity-building in these countries, including technology transfer, would help aid faster adoption of the solution.
 Such as Chlorofluorocarbons (CFCs) like R-11, R-12, and R-502; Hydrochlorofluorocarbons (HCFCs) like R-22; Hydrofluorocarbons (HFCs) such as R404A, R134a, and R 407; and natural refrigerants like CO2 and NH3.
 The total quantity of refrigerant gases in existing equipment.
 For more on the Total Addressable Market for the Materials Sector, click the Sector Summary: Materials link below.
 Current adoption is defined as the amount of functional demand supplied by the solution in the base year of study. This study uses 2014 as the base year due to the availability of global adoption data for all Project Drawdown solutions evaluated.
 For more on Project Drawdown’s three growth scenarios, click the Scenarios link below. For information on Materials Sector-specific scenarios, click the Sector Summary: Materials link.