Efficiency comparisons between CO2 and fluorocarbons


The below examples demonstrate that CO2 systems often achieve energy savings compared to HFCs systems.

Table: Efficiency comparison between CO2 and fluorocarbons





Auchen (Hungary)

Company reports energy savings of at least 35% CO2/ammonia cascading systems than with comparable R404a air-cooling systems.[1]




The company reports 10-15% energy savings with CO2 transcritical cycle refrigeration compared to HFC-404a systems.[2]




Edeka market in the north of Germany is reporting 25% energy savings running a 100% CO2 transcritical system.[3]



TEWI and LCCP studies comparing CO2 and R134a

The energy efficiency benefits of CO2 systems have been known for several years. Extensive measurements carried out at the University of Illinois in 1999 showed that CO2 MACs have at least 30% lower TEWI than HFC systems for most of the regions in Europe, US and Japan.[4] Other studies reporting on trials comparing CO2 prototypes against state-of-the-art R134a system in real situations indicate that the COP of the CO2 system was typically 25% greater than that of the R134a system. [5] Based on the Life Cycle Climate Performance (LCCP), a recent study by SINTEF research institute compared MAC systems’ total contribution with global warming in a cradle to grave approach, highlighting several benefits of R744 MAC concerning environmental performance, costs, and future potential. Namely, that R744 MAC produced up to 40% fewer emissions in hot climates (India and China) than R134a.[6]

Vending Machines


Coca-Cola has developed a new, high-efficiency, CO2 technology for vending machines. Energy savings with these units average 26%. According to Coca-Cola: “Some of our suppliers achieved even better CO2 performance versus R134a under ‘D’ conditions (40 degrees C ambient) . . . and in all countries in the world yearly averages are in a range where CO2 in beverage cold drink equipment performs better than 134a”. It has been reported that Coke’s CO2 cooler made by Haier is 35% more efficient than the ordinary HFC ones.

Vending Machines

Sanyo Electric

In 2004, Sanyo conducted field tests in Australia, comparing a  CO2 vending machines with an existing HFC based machine. The  CO2 system was optimized to replicate the operational factors of the HFC system. “The results showed “17% lower energy consumption by the  CO2 system…compared to the R134a system during the summer season.”[7]


[1] www.r744.com                  2010-03-01

[2] www.r744.com/news/view/3097                 

[4] Yin, J., Pettersen, J., McEnaney, R., and Beaver, A., "TEWI Comparison of R744 and R134a Systems for Mobile Air Conditioning," SAE Technical Paper 1999-01-0582, 1999, doi:10.4271/1999-01-0582. http://papers.sae.org/1999-01-0582

[5] Notes from Calor Gas reporting on studies by Walter & Krauss, 1999; Walter 1999; DKK 1998) and confirmed on Mercedes http://www.daimler-benz.com/ind_gfnav_e.html?/research/text/80331_e.html

[7] UNEP DTIE OzonAction : HCFC Help Centre : www.unep.fr/ozonaction/topics/hcfc_case-studies.html

“CO2 Vending Machines “ by Sanyo Electric Co. Ltd.