46 www. refrigerationandaircon. co. za RACA Journal I October 2026
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Supplied by GIZ Proklima
The industry was quick to replace CFCs with products using HCFCs, the latter having lower ODPs, but still high GWPs. Since 2007, the phase-out of HCFC refrigerants is also addressed under the Montreal Protocol. HCFCs will be phased out for production until 2030.
Partly as a direct replacement for CFCs, partly as a replacement for HCFCs, a third class of fluorinated chemicals was introduced, the HFCs. These have no ozone depletion potential, but their global warming potential( GWP) is unacceptably high, in some instances several thousand times higher than CO2. According to the Montreal Protocol, the so-called Kigali Amendment( 2016), requires the phase-down of this group of chemicals, primarily used in refrigeration, air-conditioning systems and foam insulation.
It was further discovered that several refrigerants( including CFCs, HCFCs and HFCs), contribute to global warming as they have a high GWP. In the framework of the Kyoto Protocol that entered into force in 2005, the consumption of HFC refrigerants with high GWPs has to be reported. The Kyoto Protocol, an international treaty, which was adopted as the first addition to the United Nations Framework Convention on Climate Change that committed its signatories to develop national programmes to reduce harmful emissions.
The GWP is a relative measure of how much a given mass of greenhouse gas is estimated to contribute to global warming. It is calculated over a specific time horizon, arbitrarily over 100 years, but sometimes also over 20 or 500 years. The GWP is expressed relative to carbon dioxide, with a GWP = 1. The higher the GWP value, the more a substance will contribute to global warming.
The GWP of many refrigerants is regularly revised by the Intergovernmental Panel on Climate Change. The lifetime of many HFCs is much less than 100, their main impact on the climate will therefore be on a much shorter time horizon. The average GWP20 for HFCs is 94 % greater than the GWP100 average. Hence, the GWP20 metric better reflects the true potency of HFCs during their actual time in the atmosphere.
The figure below shows several refrigerants and their respective ODP and GWP.
ODP and GWP for commonly used refrigerants.
PERSISTENT COMPOUNDS INTO THE ENVIRONMENT( FOREVER CHEMICALS) The newest class of synthetic refrigerants, unsaturated HFCs( uHFCs) also known as HFOs( hydrofluoroolefins), are responsible for introducing a persistent compound into the environment. Contrary to its predecessors, uHFCs HFOs have no ODP and a low GWP. However, their degradation product TFA( trifluoroacetic acid) has no known degradation pathway and will accumulate in water bodies, plants and soils. It is phytotoxic, i. e. toxic to some plants, and its long-term effects are not yet known.
Many uHFCs / HFOs are also flammable and / or have toxicity implications and yield dangerous decomposition products when they burn. For example, the release of hydrogen fluoride from R1234yf, that is being used in mobile air conditioning, is endangering human health, adding concerns for rescue personnel and drivers in the case of released refrigerant. The production process is typically much more energy-intensive than for conventional( saturated) HFCs.
The Rio Declaration on Environment and Development of 1992 states that:“ Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.” It urges users to apply this precautionary approach in case the impact of a substance on the environment is not fully understood yet.
LOOKING AHEAD, GREEN COOLING TECHNOLOGIES Today, industry is facing two main options regarding the future use of refrigerants. Companies could either move to unsaturated HFCs or HCFCs( so-called HFOs), which have a lower GWP but unknown impacts on the environment; alternatively, they can opt for natural refrigerants.
Natural refrigerants are not ozone-depleting and have no or negligible GWP. They were partly used in refrigeration processes until the mid-20th century. While some substances like ammonia have been in continuous use for the last century, others like carbon dioxide and hydrocarbons were‘ rediscovered’ more recently as efficient options for refrigeration.
Natural refrigerants often have higher toxicity, flammability or high operating pressure. Therefore, their use requires additional training for technicians. In addition to the selection of a suitable refrigerant, the design of the entire refrigeration system has a decisive influence on energy consumption. Most recently, the total greenhouse gas emissions during equipment lifetime has gained increased attention, demanding
46 www. refrigerationandaircon. co. za RACA Journal I October 2026