Quick answer: Hydrocarbon refrigerants such as isobutane (R-600a) and propane (R-290) do not harm the ozone layer and have a global warming potential (GWP) of about 3, compared with 1,430 for the common HFC refrigerant R-134a, according to US Environmental Protection Agency (EPA) figures. They also work efficiently, which can lower electricity bills. Their main drawback is that they are highly flammable, so they are used in small quantities in equipment built and serviced to strict safety standards.
Refrigerants are the working fluids inside refrigerators, freezers and air conditioners. They absorb heat as they evaporate inside the appliance and release it as they condense outside, changing between liquid and gas again and again. Because refrigerants can damage the ozone layer, warm the climate, or be toxic or flammable, the industry is heavily regulated. Read more about other types of refrigerants in this research article.
A short history: from ammonia to Freon to hydrocarbons
Early refrigeration and air-conditioning systems used gases such as ammonia, sulfur dioxide, methyl chloride and propane. These were toxic, flammable or both, and leaks could cause fatal accidents.
In 1928, Thomas Midgley Jr., working with Charles Kettering at General Motors, developed dichlorodifluoromethane (CFC-12, R-12), a chlorofluorocarbon that was sold under the Freon brand. CFCs seemed ideal because they were neither toxic nor flammable. An earlier version of this article described CFCs as “natural”; they are synthetic chemicals. The Freon brand, created by DuPont, now belongs to Chemours, the company DuPont spun off in 2015, which sells newer refrigerants under the same name.
Why CFCs, HCFCs and HFCs are being phased out
Scientists later found that the chlorine in CFCs destroys the stratospheric ozone layer, which shields the Earth from the sun’s harmful ultraviolet radiation. The EPA notes that CFCs also contribute to climate change: CFC-12 has a GWP of 10,900.
The Montreal Protocol phased out CFCs. Hydrochlorofluorocarbons (HCFCs) such as R-22 and R-123 were used as transitional replacements because they do less damage to the ozone layer, but they are being phased out too. In the US, production and import of HCFC-22 ended in 2020, and production and import of all HCFCs is due to end in 2030, according to the EPA.
Hydrofluorocarbons (HFCs) do not damage the ozone layer, but many are powerful greenhouse gases. The Kigali Amendment to the Montreal Protocol, agreed in October 2016 and in force from 1 January 2019, phases down HFCs. Developed countries must cut HFC use to 15% of their baseline by 2036. India’s Union Cabinet approved ratification in August 2021, and India’s schedule cuts HFCs by 10% in 2032, 20% in 2037, 30% in 2042 and 80% in 2047.
An earlier version of this article said the ozone hole caused the polar ice caps to melt. That mixed up two different problems. Ozone depletion lets more ultraviolet radiation reach the ground; global warming is driven by greenhouse gases. Some refrigerants, including CFCs and many HFCs, contribute to warming as greenhouse gases.
Common hydrocarbon refrigerants
Refrigerants carry “R” numbers under the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 34 naming system. The original list in this article contained a few wrong numbers, corrected below.
| Refrigerant | R-number | Notes |
|---|---|---|
| Isobutane | R-600a | Widely used in household refrigerators. (The original list said R-600, which is normal butane.) |
| Propane | R-290 | Used in refrigerators, freezers, commercial display cases and some air conditioners and heat pumps. |
| Ethane | R-170 | A component of some refrigerant blends, such as R-441A. |
| Pentane | R-601 | A heavier hydrocarbon; cyclopentane is widely used to blow refrigerator insulation foam. |
| Ethene (ethylene) | R-1150 | Also a component of some low-temperature blends listed by ASHRAE. |
| R-441A | R-441A | Blend of ethane, propane, isobutane and n-butane. |
| R-436A | R-436A | Blend of 56% propane and 44% isobutane. (The original list said “R-136A”.) |
| R-433C | R-433C | Blend of 25% propene (propylene) and 75% propane. |
Today, hydrocarbon refrigerants are used in household refrigerators, freezers, air conditioners, cold storage, food processing freezers, supermarket cabinets, heat pumps, chillers, industrial refrigeration and vending machines. They are versatile and work across many temperature ranges. Learn more about hydrocarbons in general at https://www.investopedia.com/terms/h/hydrocarbon.asp.
Advantages of hydrocarbons as refrigerants
With CFCs and HCFCs phased out and HFCs being phased down, hydrocarbon refrigerants are one of the main alternatives. Their benefits are:
Very low climate impact and no ozone damage
Hydrocarbons contain no chlorine, so they do not deplete the ozone layer. In the EPA’s table (using values from the Intergovernmental Panel on Climate Change’s Fourth Assessment Report), isobutane has a GWP of 3 and propane 3.3, compared with 1,430 for HFC-134a, which many refrigerators used before.
Good energy efficiency
The efficiency of a refrigerator or freezer is measured by its coefficient of performance (COP): the amount of cooling it delivers divided by the electricity it uses. The EPA says hydrocarbon refrigerants improve the energy efficiency of refrigerators compared with HFC-134a, which saves consumers money. Hydrocarbons absorb a large amount of heat as they evaporate (their latent heat of evaporation), which helps them cool effectively.
Lower running costs
A more efficient appliance uses less electricity, which lowers running costs over its life. The saving matters most for equipment that runs around the clock, such as the laboratory freezers used to store research and clinical samples. If you run a laboratory, compare the energy ratings of hydrocarbon-based models with older designs, and choose a design whose reliability and sample protection match your needs.
Proven in the mass market
The EPA reported in 2016 that hydrocarbon refrigerants already dominated the household refrigerator market in Europe, Japan and China. In the US, they entered the market in 2010, when GE introduced a refrigerator line using isobutane.
The main drawback: flammability
Under ASHRAE Standard 34, refrigerants are classed by toxicity (A for lower, B for higher) and flammability (1, 2L, 2 and 3). Hydrocarbons are class A3: lower toxicity but highly flammable. That is why:
- Appliances using them hold only small amounts of refrigerant, and safety standards set charge limits and design rules. In the US, the EPA lists hydrocarbon refrigerants for household refrigerators as acceptable only with use conditions.
- Repairs should be done only by technicians trained to handle flammable refrigerants, with no open flames or sparks nearby.
- A hydrocarbon should never be used to “top up” or convert a system designed for a different refrigerant. Use only the refrigerant named on the appliance’s rating plate.
Lowering your cooling bills is only half the picture. If you are also looking at the electricity supply itself, see our guide on whether solar is a good investment for your home.
Frequently asked questions
Which refrigerant does my refrigerator use?
Check the rating plate or label, usually inside the fridge or on the back near the compressor. It names the refrigerant (for example R600a or R134a) and the amount charged.
Are hydrocarbon refrigerants safe at home?
Appliances designed for them are built to safety standards that limit the amount of refrigerant and control ignition sources. The risk comes from poor repairs or from putting a hydrocarbon into equipment not designed for it, so use trained technicians.
Is Freon banned?
The original Freon refrigerant, CFC-12, has been phased out under the Montreal Protocol. Freon is now a Chemours brand name used for other refrigerants, so check the R-number rather than the brand.
What is the Kigali Amendment?
It is a 2016 amendment to the Montreal Protocol that phases down HFC refrigerants because of their climate impact. India approved ratification in 2021 and will cut HFC use in steps from 2032 to 2047.
What does GWP mean?
Global warming potential compares how much a gas warms the climate with the same mass of carbon dioxide over a set period. A GWP of 3 means about three times the warming effect of CO2; 1,430 means about 1,430 times.
Checked in October 2026 against the US EPA’s domestic refrigeration fact sheet and HCFC phase-out pages, ASHRAE’s refrigerant safety classification fact sheet, UNEP’s text of the Kigali Amendment and the Indian government’s 2021 cabinet release. Always follow the appliance maker’s instructions and local regulations when servicing cooling equipment.
