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Contribution of Refrigerant Emission to Total Heat Pump Emissions

Illustration, comparison will depend on climatic conditions, emissions intensity for electricity generation and application. Assumes heat pumps with 4% annual emission rate, 15% end of life emissions and 15 years lifetime. Hermetic (monobloc) heat pumps have essentially no annual leakage except due to failures, but do have end of life emissions, reducing the contribution of refrigerant emissions to the total heat pump emissions.

For this example, HFC-410A contributes about 9% of the emissions due to the heat pump for the EU CO2 emissions intensity for electricity generation (but depending on climatic conditions and application). The switch to HFC-32 and A2L HFC/HFO refrigerants with similar GWPs reduces the refrigerant emissions contribution to about 3%. The use of R-454C with a GWP of 148 or similar HFC/HFO blends reduces the refrigerant contribution to about 0.7%. For larger heat pumps that may be used for district heating or industrial applications with compressors that can use lower pressure HFO refrigerants with a GWP <1 the contribution due to refrigerant emissions is insignificant (<0.005% at GWP=1). Reducing annual leak rates and end of life emissions will reduce these contributions further.

A report for the UK Department of Energy and Climate Change addresses the net benefit of heat pumps in the UK, taking into account the environmental costs associated with refrigerant leakage and came to similar conclusions The primary research and modelling indicated that whilst leakage led to significant CO2 emissions, this was nonetheless a small proportion of the total reduced emissions associated with heat pump technologies. It also highlights that there is scope to reduce leakage further, thereby increasing the net benefit associated with heat pumps.

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