What is GWP and how does it relate to heat pumps?
Efforts to combat climate change are increasingly influencing the choice of heating solutions. One of the most important metrics for assessing environmental impact is the GWP value – but what does it mean, and why is it important when selecting a heat pump?
GWP in a nutshell
GWP (Global Warming Potential) describes how much heat a specific gas traps in the atmosphere compared to carbon dioxide (CO₂). The GWP of CO₂ is defined as 1. For example, a GWP value of 750 means the gas warms the atmosphere 750 times more than the same amount of CO₂.
Why is heat retention in the atmosphere harmful? It’s due to the greenhouse effect. Solar radiation warms the Earth, and part of that heat reflects into space. Certain gases – such as CO₂, methane, and many refrigerants – allow sunlight through but trap the heat from escaping. They absorb and retain thermal radiation, which causes warming of the atmosphere and accelerates climate change.
The higher the GWP value of a gas, the more heat it traps – and the greater its negative impact on the climate.
The emission impact is expressed as CO₂ equivalent (CO₂e), calculated by multiplying the amount of gas (in kilograms) by its GWP. For example, a one-kilogram leak of a refrigerant with a GWP of 750 results in 750 kg CO₂e, or 0.75 tonnes of CO₂-equivalent emissions.
Refrigerant in Heat Pumps
In heat pumps, the refrigerant acts as a medium that transfers thermal energy from the ground or another heat source to the building’s heating system. In ground source heat pumps (also known as brine-to-water or liquid-to-liquid heat pumps), the refrigerant circulates in a closed loop inside the unit — through the evaporator, compressor, condenser, and expansion valve, collectively known as the refrigeration circuit. As the refrigerant evaporates and condenses at different pressure and temperature levels, it enables efficient heat transfer. Although the system contains only a small amount of refrigerant, a potential leak can have a significant environmental impact — which is why the choice of refrigerant is so important.
GWP values of refrigerants vary significantly
There are several refrigerants on the market, and their GWP values differ greatly:
- R410A: GWP approx. 2088
- R454B: GWP approx. 466
- R290 (propane): GWP only 0.02
The difference between the highest and lowest GWP values is enormous. For example, R290 is over 100,000 times more climate-friendly than R410A.
Choosing a low-GWP refrigerant is a climate-friendly act
When selecting a heat pump, the refrigerant’s GWP is becoming an increasingly important criterion – especially for companies and property owners who value sustainability. A low-GWP solution can:
- reduce the carbon footprint of the property
- help meet future environmental regulations
- strengthen a brand’s responsibility image
- be a more future-proof investment as the refrigerant remains allowed longer
Legislation guides the transition to low-emission alternatives
Under the latest EU F-gas regulation, high-GWP refrigerants are being gradually phased out. From the beginning of 2027, heat pumps under 50 kW placed on the market must use refrigerants with a GWP no higher than 150. The same limit applies to devices over 50 kW starting in 2030. Read more: The F-gas Regulation encourages industry to use natural refrigerants
In practice, this means heat pumps with higher-GWP refrigerants can still be installed, used, and serviced, but new units cannot be brought to market after the regulation takes effect.
For this reason, many manufacturers – including us at Gebwell – have shifted to developing and producing heat pumps that use R290 refrigerant, which is both efficient and environmentally sustainable.
Summary
GWP is a key metric for assessing the environmental impact of heat pumps. By choosing a low-GWP refrigerant – like R290 – one can make a significant climate-friendly decision without compromising on performance.