Environmental impact of fluorinated greenhouse gases and ODS
Two different damage mechanisms
Candidates must never confuse GWP and ODP. GWP (global warming potential) compares a gas's 100-year warming effect with CO2 = 1 and is the basis of every F-Gas threshold. ODP (ozone depletion potential) compares chlorine/bromine-driven ozone destruction with CFC-11 = 1. HFCs are powerful greenhouse gases but have zero ODP; HCFCs such as R-22 are both ozone-depleting and high-GWP, which is why R-22 use for maintenance has been banned since 2015 while HFCs remain in use under a phase-down.
Use IPCC AR4 values as used by the F-Gas Regulation: R-134a 1430, R-32 675, R-407C 1774, R-410A 2088, R-404A 3922, R-22 1810. The conversion is:
tCO2e = mass in kg × GWP ÷ 1000
Remember that the environmental impact of a system is not only the refrigerant: indirect emissions from electricity use over the equipment's life usually dominate, which is why the F-Gas phase-down pushes towards lower-GWP refrigerants and why efficiency matters. TEWI (total equivalent warming impact) combines direct refrigerant losses with indirect energy emissions.
Traps
- Assuming HFCs damage the ozone layer - they do not.
- Using kg instead of tCO2e when comparing systems.
- Forgetting that the phase-down is measured in CO2 equivalent, so 1 kg of R-404A counts far more heavily than 1 kg of R-32.
Worked example
A plant holds 12 kg of R-404A. Direct charge in CO2 terms = 12 × 3922 ÷ 1000 = 47.1 tCO2e. The same duty met with 12 kg of R-32 = 12 × 675 ÷ 1000 = 8.1 tCO2e - roughly a six-fold reduction in charge-related impact.