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Page 8 of 14 Li et al. Carbon Footprints 2024;3:6 https://dx.doi.org/10.20517/cf.2023.54

Quantifying the carbon emissions at the fleet level for automotive air conditioning is instrumental in
providing insights for the formulation of low-carbon policies, particularly those related to the replacement
of fluorinated refrigerants. The forecasted fleet carbon emissions for various refrigerant technologies in
automotive air conditioning from 2022 to 2060 are presented in Figure 4. This calculation encompasses both
EVs and ICEVs, with the carbon emission data for ICEV air conditioning products referencing the LCCP
[17]
model . The prediction of vehicle fleet size draws on the forecast by Xiang et al., which projects that
China’s vehicle fleet will reach 401 million units by 2030, saturating at 645 million units by 2057 . The
[27]
electric vehicle fleet is expected to constitute 9.6% of the total in 2025, achieving market parity with ICEVs
by 2035, and reaching a fleet size of 641 million units by 2060. As depicted in Figure 4, carbon emissions in
China’s automotive air conditioning industry will increase with the growth of the vehicle fleet size, peaking
around 2040-2045 before gradually declining. At the industry level, the R290 technology route still exhibits
the lowest fleet carbon emissions. The adoption of R290 refrigerant as a replacement for R134a is projected
to result in a cumulative reduction of approximately 3.88 billion tons of carbon dioxide in the automotive
air conditioning industry. The adoption of the R1234yf refrigerant would result in an estimated cumulative
reduction of approximately 2.41 billion tons of carbon dioxide when replacing R134a.

Interestingly, the fleet carbon emissions of R744 refrigerant are higher than R134a. This is attributed to the
high-temperature efficiency degradation of R744 air conditioning systems, leading to huge operational
carbon emissions in the fleet’s air conditionings. Additionally, considering that R134a refrigerant still
predominates in China’s automotive air conditioning industry, the calculated carbon emissions for the fleet
in 2022 are approximately 162 million tons of carbon dioxide equivalent. This represents approximately
1.17% of the total national greenhouse gas emissions and approximately 6.16% of the greenhouse gas
[27]
emissions caused by national road traffic . Therefore, achieving emissions reduction in the automotive air
[28]
conditioning industry plays a crucial role in driving the low-carbon transformation of urban transportation.

Following the LCA of the emission reduction potential of low-GWP refrigerants, we proceeded to employ
LCCA model to evaluate the cost-effectiveness of replacing low-GWP refrigerants in electric vehicle air
conditioning, as depicted in Figure 5. Figure 5 illustrates significant variations in the life cycle cost of electric
vehicle heat pumps with different refrigerant technology choices across various regions in China, where the
values on the color-shaded slide bar refer to distinct LCC range values. This discrepancy is attributed to the
vast expanse of China, spanning multiple climatic zones. The disparities in climate data among different
geographical regions result in substantial variations in the operational loads of electric vehicle air
conditioning, consequently leading to pronounced differences in LCCA outcomes for different cities.
Therefore, it may be more reasonable for cities located in different climatic zones to adapt refrigerant
replacement choices that are suitable for their specific local conditions.

Subsequently, mirroring the preceding carbon emission analysis, we have augmented the study by including
the technology of AC + PTC for comparative purposes. The life cycle NPV costs of various electric vehicle
air conditionings under national average conditions are depicted in Figure 6A. From Figure 6A, it is
observable that while the CapEx for AC + PTC technologies is the most economical, the considerably lower
energy efficiency of PTC leads to exceptionally high OpEx over the life cycle. The total life cycle NPV cost of
AC + PTC technology surpasses those of R134a, R1234yf, and R290 heat pumps.

Among heat pump air conditionings using the low-GWP refrigerants R1234yf, R744, and R290, the R290
heat pump exhibits the lowest life cycle cost, thus indicating superior cost-effectiveness under national
average conditions. The R134a heat pump is currently the predominant solution for electric vehicle air
conditioning, with an NPV life cycle cost of approximately 11,500 CNY. The OpEx of R1234yf heat pump