IN SHORT
• The climate impact of refrigerants is generally expressed as GWP over 100 years. GWP compares the climate effect of 1 kg of refrigerant with that of 1 kg of CO₂ over the same period.
• GWP20 looks at the same ratio, but over a period of 20 years. Especially for relatively short-lived greenhouse gases, this value can be significantly higher than the GWP100 value.
• GWP100 remains the commonly used metric within the refrigeration industry and F-gas legislation. GWP20 can provide additional insight into climate impact over a shorter time horizon.
• The choice of refrigerant goes beyond GWP alone. Other environmental effects, such as degradation products and how long they remain in the environment, can also be taken into account.
Global Warming Potential (GWP) is a metric used to compare the climate effect of a greenhouse gas with that of CO₂.
It looks at the integrated climate effect following the emission of 1 kg of a greenhouse gas compared with 1 kg of CO₂, over a defined period of time.
The most commonly used time horizon is 100 years: GWP100. GWP20 uses the same comparison, but focuses on the first 20 years after emission.
The GWP value of a refrigerant therefore depends partly on the selected time horizon. This is because greenhouse gases differ in how strongly they retain heat and how long they remain in the atmosphere.
For various fluorinated refrigerants, the GWP20 value is higher than the GWP100 value. This means that their climate effect relative to CO₂ can be stronger during the first twenty years.
An important distinction should be made here: a higher GWP20 does not mean that the total climate impact over twenty years is greater than over one hundred years. GWP is a ratio relative to CO₂, and that ratio changes depending on the selected time horizon.
For greenhouse gases that remain in the atmosphere for a relatively short period, GWP20 can therefore provide additional information about their contribution to warming in the shorter term.
For natural refrigerants such as R744 (CO₂), R717 (ammonia) and R290 (propane), the direct climate impact remains relatively limited.
Although GWP20 is a recognised scientific metric, GWP100 is primarily used in climate policy and within the refrigeration industry.
The European F-gas Regulation also uses a 100-year time horizon as the basis for defining and assessing GWP. GWP100 therefore forms the basis for, among other things, statutory GWP values and the calculation of CO₂ equivalents.
GWP20 does not replace this metric. It can, however, be used as an additional comparison to provide greater insight into the climate effect of a refrigerant over a shorter time horizon.
When switching to refrigerants with a lower GWP, it is important not to focus solely on one figure. Other technical and environmental effects can also play a role.
HFOs and various A2L refrigerants, for example, generally have a lower GWP100 than many older HFC refrigerants. At the same time, certain fluorinated refrigerants can form substances such as trifluoroacetic acid (TFA) when they break down in the atmosphere.
TFA is hardly broken down any further and is found in, among other places, water and soil. As a result, there is growing attention for the potential environmental impact of such degradation products.
This makes it relevant to consider not only the direct contribution to global warming when selecting a refrigerant, but also other possible environmental effects.
Reducing greenhouse gas emissions remains an important principle when designing refrigeration and heating systems. At the same time, it is important to consider the overall impact of a refrigerant.
Natural refrigerants such as CO₂, ammonia and propane have a low direct climate impact and do not present the same concerns regarding persistent fluorinated degradation products as various synthetic refrigerants.
Which solution is most suitable ultimately depends on much more than GWP alone. Factors such as the application, safety, temperatures, system design, energy consumption and operational requirements also play a role.
GWP20 can be used when, in addition to long-term impact, insight is also required into the climate effect of a refrigerant over a shorter time horizon.
The twenty-year time horizon is independent of the technical lifetime of an installation. For each individual emission, the climate effect is assessed over the twenty years following that emission.
For example, if a refrigerant leaks from an installation after fifteen years of operation, GWP20 considers the twenty years following that specific emission. GWP20 therefore does not indicate how much climate impact an installation causes during its first twenty years of operation.
In practice, GWP100 remains the primary metric. Looking at GWP20 as an additional measure can nevertheless help show how different refrigerants behave relative to CO₂ over a shorter time horizon.
When comparing refrigerants, it is therefore advisable to look beyond a single figure. GWP100 provides the commonly used basis, while GWP20 can offer additional context. By also considering technical characteristics and other environmental effects, a more complete picture of a refrigerant choice can be formed.
Would you like to discuss the choice of refrigerant for a new or existing installation? Our specialists will be happy to assist.
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GWP20 compares the warming potential of a greenhouse gas over 20 years, while GWP100 assesses the same impact over 100 years. For refrigerants with a relatively short atmospheric lifetime, the shorter time horizon can show a higher relative climate impact.
Many cooling and air conditioning systems have a technical lifespan of approximately 20 years. During that period, refrigerant can be released through leaks, maintenance, or service work. GWP20 can therefore provide additional context regarding the climate impact during the system's operational life.
Not necessarily. GWP is just one component of the total environmental impact. Other aspects, such as degradation products and persistence in the environment, can also be relevant. That is why it is important to evaluate refrigerants more broadly than just based on a single GWP value.
GWP100 remains an important and widely used metric, but it does not provide the full picture in every situation. For refrigerants that contribute significantly to warming over a shorter period, GWP20 can provide additional information. Especially for systems with a lifespan of about 20 years, this time horizon helps to better weigh the climate impact during the operational period.
Anyone comparing refrigerants would therefore do well to look beyond a single number. By placing GWP20 and GWP100 side by side and also considering other environmental effects, a more complete picture of the total impact of a refrigerant choice emerges.
Would you like to discuss the refrigerant choice for a new or existing system? Our specialists are happy to help.
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