• SkillCat Team

Global Warming Potential

Updated: 2 days ago

EPA 608 Core Chapter 20 (Take full course for free)


In this module, we will discuss the properties of different refrigerants. As we discussed in the previous module, certain refrigerants destroy the ozone layer. Other refrigerants can be harmful in other ways, which we will explore in this module. Skip to quiz!


1. Global Warming


Aside from potential to deplete the ozone layer, certain refrigerants also contribute to global warming. Let’s take a look at a short video to review the basics of global warming.




As discussed in the video, gases like carbon dioxide (CO2) naturally trap heat in the atmosphere. This makes Earth warm enough to be livable for us humans. We refer to these gases as greenhouse gases.


But an increase in these greenhouse gases traps more and more heat from the sun. This leads to a disruption in the balance of life on earth, leading to extreme weather events. Some gases are more potent at trapping heat in the atmosphere than others.


2. GWP Number

We measure how much a gas contributes to global warming with a number called the Global Warming Potential (GWP). This number is different for each gas. GWP measures how much energy one ton of gas will absorb over 100 years compared to carbon dioxide.


By definition, carbon dioxide has a GWP of 1 because it is the gas we use as a reference to compare other gases to. If the GWP of a substance is greater than 1, then it has a higher global warming potential than CO2.


The higher the GWP, the more heat the gas traps in the atmosphere. For example, if a gas has a GWP of 2, it means it will absorb two times as much energy as carbon dioxide over 100 years. If a gas has a GWP of 500, it means it will absorb five hundred times as much energy as carbon dioxide over 100 years.


GWP is a number that quantifies the effect of a chemical on the environment. It allows policymakers to compare and make decisions on what regulations are needed.


3. GWP Comparison


Let’s take a look at the global warming potentials of a few refrigerants. This table shows five different refrigerants. It includes their trade names and global warming potentials (GWPs).


Refrigerant Type ASHRAE Number GWP


CFC R-12 10900

HCFC R-22 1810

HFC R-410a 2088

HFO R-1234yf 4

HFO R-1234yf 3

Notice that R-12, a CFC refrigerant, has the highest GWP. R-12 has a GWP of 10,900, meaning it has a global warming potential of almost 11,000 times more than carbon dioxide.


We see here that R-410a, an HFC refrigerant, has a higher GWP than R-22, an HCFC refrigerant.


This is noteworthy because recall that HFCs were produced as an alternative to HCFCs. HFCs do not deplete ozone but they do contribute to global warming. This is why HFCs are also being phased out, as we discussed in Key Regulations.


Compared to all of the other refrigerants on this list, we see that the refrigerants with the least global warming potentials are:

  • R-1234yf, which is an HFO refrigerant

  • R-600a, which is an HC (hydrocarbon) refrigerant

This chart reflects the fact that the type of refrigerant corresponds to its global warming potential. In general, CFCs have the highest global warming potential. We see in this chart that the R-12 refrigerant has a GWP much larger than the others.


HFOs and HCs have the lowest global warming potential. Recall that HFOs and HCs were developed after CFCs, HCFCs, and HFCs. They were developed to provide an alternative to the high global warming potential of HFCs.


4. Conclusion


In this module, we discussed the characteristics of different types of refrigerants. Certain refrigerants deplete the ozone, others have high global warming potential. We also have to consider the different classes of safety of individual refrigerants in order to take proper safety precautions.


Question #1: Which gas is used as a reference for measuring GWP?

  1. CFC

  2. HCFC

  3. Ozone

  4. Carbon Dioxide

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Carbon dioxide is used as a reference in measuring global warming potential (GWP).


Question #2: GWP is a measure of how much energy a gas traps in the atmosphere over 100 years

  1. True

  2. False

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GWP is a measure of how much energy a gas traps in the atmosphere over a 100 years compared to carbon dioxide. GWP is not a measure of the amount of energy.


Question #3: Which of the following are true?

  1. Carbon dioxide has a GWP of 1

  2. Carbon dioxide has a GWP of 0

  3. Carbon dioxide has an ODP of 0

  4. Carbon dioxide has an ODP of 1

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Carbon dioxide has a GWP of 1. GWP is a comparison of how much energy a gas absorbs over a 100 years, compared to carbon dioxide.

Carbon dioxide has an ODP of 0. because it does not contain chlorine so it does not destroy ozone.


Question #4: If a gas has a GWP of 50, it means it has 50 times less global warming potential than carbon dioxide.

  1. True

  2. False

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A GWP of 50 means the gas has fifty times more global warming potential than carbon dioxide. It means that this gas will retain fifty times the amount of energy in the atmosphere as carbon dioxide over a hundred years.


Question #5: Of the following refrigerants, which one has the highest global warming potential (GWP)?

  1. R-12

  2. R-22

  3. R-410a

  4. R-1234yf

Scroll down for the answer...











As we saw in the chart earlier, the refrigerant with the highest global warming potential is R-12, which is a CFC refrigerant. It has a GWP of 10,900.

This means that it retains almost 11,000 times more than the amount of energy that carbon dioxide would trap in the atmosphere!


Question #6: Of the following refrigerants, which one has the least global warming potential (GWP)?

  1. R-12

  2. R-22

  3. R-410a

  4. R-1234yf

Scroll down for the answer...











As we saw earlier with the chart, R-1234yf has the least GWP. It is an HFO refrigerant and has a GWP of only 4.


Question #7: R-12 has a GWP in which of the following ranges?

  1. 1-500

  2. 500-1000

  3. 1000-10,000

  4. 10,000-50,000

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R-12 has a GWP of 10,900. This means it has close to 11,000 more global warming potential than carbon dioxide.10,900 would fall between 10,000 and 50,000.


Question #8: R-410a has a GWP in which of the following ranges?

  1. 1-500

  2. 500-1000

  3. 1000-10,000

  4. 10,000-50,000

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R-410a has a GWP of 2088, which means it has 2088 times more global warming potential than carbon dioxide. 2088 falls in between 1000 and 10,000.


Question #9: Which types of refrigerants have the lowest GWPs? (Select two)

  1. CFCs

  2. HFCs

  3. HFOs

  4. HCs

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HFOs and HCs have the lowest GWPs.


Question #10: The GWPs of HFOs and HCs are close to those of HCFCs.

  1. True

  2. False

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False. The GWP of HFOs and HCs are in the single digits, while those of HCFCs are in the thousands.


Question #11: The GWP of R-290 is greater than which of the following? (Select all that apply)

  1. R-410a

  2. R-134a

  3. R-22

  4. None of these

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R-290 is greater than none of these refrigerants. Recall that R-290 is propane, which is a hydrocarbon. We mentioned that hydrocarbons, or HCs, have the lowest GWPs.

Answer choices a, b, and c are either HCFC or HFC refrigerants, which have GWPs in the thousands.


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