CO2 is a naturally occurring substance which is found in abundance throughout our environment; it is in the air that we breathe and the beverages that we drink.
CO2 has a global warming potential (GWP) of just one, thousands of times lower than many traditional
Furthermore, with an Ozone Depletion Potential (ODP) of zero, CO2 has no effect on the ozone layer, making it a sustainable and environmentally sound
Increasingly stringent environmental legislation sees
operators of refrigeration systems under increasing pressure to reduce or eliminate their use of
traditional, high-GWP refrigerants.
This is highlighted by the revised EU F-Gas
Regulation (517/2014), which will see the
availability of HFCs reduced by 79% between the years of 2015 and 2030, whilst simultaneously introducing step-wise bans on the installation and servicing of systems using higher-GWP refrigerants.
CO2 has an A1 safety rating (BS EN378-1: 2016), being classified as non-flammable with low toxicity. As a result, CO2 systems are straightforward to implement, with fewer safety stipulations than systems using toxic or flammable refrigerants.
CO2 operates at higher pressures than traditional refrigerants; a factor which should be considered when designing the system.
It is interesting to note however that the higher pressures associated with CO2 also result in smaller compressors and system components. CO2 is not classed as an F-Gas and may be vented directly to atmosphere if necessary.
In addition to favourable environmental and safety qualities, CO2 systems also offer attractive energy
CO2 is very effective at transferring heat, allowing higher
evaporating temperatures than many traditional refrigerants. It is also relatively insensitive to pipe work pressure drops, resulting in higher suction pressures and
Mild climates such as the United Kingdom are ideal for air cooled transcritical CO2 systems, allowing them to function in their most efficient operating mode for large portions
of the year.