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Last edited 01 Apr 2022
Halocarbons are defined in the Global Warming Glossary as ‘ A collective term for the group of partially halogenated organic species, including the chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), halons, methyl chloride, methyl bromide, etc. Many of the halocarbons have large Global Warming Potentials. The chlorine and bromine-containing halocarbons are also involved in the depletion of the ozone layer.'
From the 1930s, CFCs became widely used in the United States for residential, commercial and automotive air conditioning systems. Initially, CFCs were thought to be completely safe due to their non flammable characteristics, low toxicity and stability.
However, in the 1970s, scientists discovered that the potential impact of emissions from CFCs on the upper atmosphere (or stratosphere) might be cause for concern. Research conducted by University of California chemists Professor F. Sherwood Rowland and Dr Mario Molina found that CFCs emit significant amounts of inorganic chlorine in the upper atmosphere, and this was seen as a contributing factor to ozone depletion.
The decision to phase out the production of CFCs came as a result of the Montreal Protocol, which was agreed on 16 September 1987 and came into effect on 1 January 1989. The Protocol introduced an incremental reduction of the manufacture, import, export and consumption of CFCs and other substances that deplete the ozone layer. In 1990, an amendment to the Protocol escalated the commitment to cease production of CFCs by 2000. In 1996, the production ban in major countries came into effect.
New equipment using HCFCs was banned in 2001 (2004 for small air-conditioning systems), and the use of virgin HCFCs was banned in 2010, when it also became illegal to manufacture HCFC refrigerants or for suppliers to keep them in stock. New production and import of most HCFCs were phased out as of 2020.
From 1 January 2015, EC regulation EC/1005/2009, which relates to substances that deplete the ozone layer, prohibited the use of HCFCs in any form, even for maintenance, in order to protect the ozone layer. A restriction introduced at this time also prevented the use of recycled and reclaimed HCFCs.
These regulations did not prohibit continued operation of plant using existing quantities of HCFC refrigerant but prevented invasive maintenance, replacement or topping up. However, badly maintained equipment or old HCFC systems may not lend themselves to conversion and could need complete replacement with a compliant HFC, hydrocarbon, ammonia or carbon dioxide system.
NB HFCs are also greenhouse gases, albeit not as powerful as CFCs or HCFCs. Demand for HFCs has increased rapidly following the phasing out of CFCs and HCFCs and this has been exacerbated by the growth of air conditioning in developing nations. As a result, on 15 October 2016 it was announced that 170 countries in Kigali, Rwanda, had agreed that HFCs should be phased down through an amendment to the Montreal Protocol.
- Chiller units.
- Chlorofluorocarbons CFCs.
- Deleterious materials in construction.
- Greenhouse gases.
- HFC phase out.
- Kyoto Protocol.
- Montreal Protocol.
- Ozone-depleting substances
- R22 phase out.
- Refrigerants in buildings.
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