Carbon neutrality: heat pumps have a role to play!

With sales expected to grow by 38% in Europe by 2022, heat pump manufacturers are stepping up the development of their equipment using fluids with low environmental impact.

The gradual replacement of fossil fuel burners with more environmentally-friendly renewable energy solutions, such as heat pumps, contributes to the goal of reducing carbon emissions. 

It's often said that heat pumps work like a refrigerator in reverse. They transfer heat from the outside air, ground or water into a building, and raise its temperature for use in a heating system.


The two most commonly installed types of heat pump are air-to-air and geothermal. Air-source heat pumps are the most popular on the market, reputed to be less expensive and easier to install. Geothermal heat pumps, considered more efficient, have a longer lifespan and provide a constant flow of heat through the seasons. They require pipes to be laid in the ground, making them more expensive to install. They are particularly suitable for new buildings.


In Europe, there are still millions of boilers in service that will need to be replaced in the coming years. Governments are increasingly encouraging the deployment of low-carbon heating technologies.


The evolution of refrigerants in heat pumps


An essential component of any heat pump is the refrigerant required for the vapour compression cycle, which for many years was mainly R-410A and R-134a. With the emphasis on sustainable development, and a GWP of 2088, R-410A is no longer at all suitable for new equipment.


Equipment manufacturers now use low GWP** refrigerants such as R-32 (GWP 675) and R-454B (GWP 466). Some low-charge hermetic monobloc systems use R-290 or R-134a. Most ground-source heat pumps, which previously used R-407C, are now switching to R-454C or R-455A, both of which have a very low GWP of 148. 

Some low-GWP refrigerants have a degree of flammability. As long as the installer is trained in safety and installation, their use should be acceptable. In the long term, R-1234yf (GWP 4) or R-1234ze (GWP 7) will be used in place of R-134a. R-513A (GWP 631) can easily be replaced in the short term.

In some specialized applications, R-744, R-1233zd, propane and ammonia are used as refrigerants.



Combining bio-sourced heat transfer fluids with ultra-low GWP fluids: a winning combination


Air/water or geothermal heat pumps use a heat transfer fluid, heating it in the heat exchanger with compressed refrigerant, raising its temperature to suit the system.



A closed-loop geothermal heat pump circuit circulates the heat transfer fluid through a set of underground pipes, while an open-loop system uses groundwater for the heat exchange process and extracts it after use. Open loops are generally simpler and less costly to install, but may require more maintenance.

Traditionally, heat transfer fluids are based on mono propylene glycol (MPG), a product of the petrochemical industry. With the emphasis on carbon reduction targets, it's time to consider alternatives to conventional heat transfer products. One such product is Greenway® Neo Heat Pump N, a plant-based fluid formulated from biosourced 1,3-propanediol. Plants are harvested, fermented and refined to produce this biotechnology.


The use of a biodegradable product such as Greenway® Neo Heat Pump N reduces the risk of soil pollution in the event of leakage, which is particularly important in a heat pump system, and provides excellent protection against corrosion. What's more, the production process for bio-based 1,3-propanediol consumes less energy and emits less CO2 than MPG or synthetic chemicals, helping to reduce the ecological footprint.


In concrete terms, replacing oil-fired boilers with heat pumps that consume less energy and are charged with low environmental impact process fluids is the first step in a responsible approach. All heat pumps need electricity to operate, but they can provide highly energy-efficient heat, with a high coefficient of performance (COP) of up to 5, whereas the best condensing boilers only have a COP of 0.9.

Equipment manufacturers are continuing their research and development to meet decarbonization targets.