Refrigerants: everything you need to know about their types and uses

Choosing the right refrigerant today is not just a technical matter. It is a decision that directly affects the efficiency, safety, environmental impact and regulatory compliance of your air conditioning systems and heat pumps.

The sector is undergoing a true revolution, driven by new European regulations and a growing focus on sustainability. In this article, I will guide you through the history, types, selection criteria and future of refrigerants, with a focus on the safest and most advanced solutions for the HVAC sector.

A brief history of refrigerants

In the 1930s and 1940s, the first refrigeration and air conditioning systems used ammonia and carbon dioxide as natural refrigerants. These substances were efficient, but presented some critical issues in terms of safety and handling.

Over time, to meet safety and ease-of-use requirements, the industry introduced CFCs (chlorofluorocarbons) and later HCFCs (hydrochlorofluorocarbons). These gases dominated the market for decades thanks to their stability and ease of use, but were later found to be harmful to the ozone layer and the climate.

In the 1990s, growing environmental awareness and the Montreal Protocol marked the beginning of the phase-out of CFCs and HCFCs. This led to the introduction of HFCs (hydrofluorocarbons), which contain no chlorine and are therefore harmless to the ozone layer, but still have a significant impact on global warming (high GWP).

Today, the challenge is to minimise environmental impact. For this reason, natural refrigerants (such as ammonia, CO₂ and hydrocarbons) and new HFOs (hydrofluoroolefins), characterised by a very low GWP, are becoming increasingly widespread.

What refrigerants are and how they work

The refrigerant is the fluid that enables heat exchange in air conditioning systems, heat pumps and chillers. Its role is to absorb heat from a source (for example, outdoor air) and release it where it is needed (inside the building or into technical water).

The operating principle is based on evaporation and condensation cycles: the refrigerant evaporates at low pressure, absorbing heat, then is compressed and condensed at high pressure, releasing heat.

This cycle repeats continuously, allowing thermal energy to be transferred efficiently.

The main types of refrigerants

Today, refrigerants in use are divided into three main families. Below is an overview of their main characteristics:

HFCs (hydrofluorocarbons)

HFCs such as R410A and R32 were introduced in response to the phase-out of CFCs and HCFCs. They are low-toxicity, stable and non-flammable, but still have a GWP that is too high for current standards (R410A: GWP 2080, R32: GWP 675). They are expected to be progressively phased out, especially in the residential sector, due to new European restrictions.

HFOs (hydrofluoroolefins)

HFOs represent the new frontier of synthetic refrigerants. They have a very low GWP and reduced environmental impact. One example is R1234ze. However, many HFOs are slightly flammable (A2L class according to ISO 817), and therefore require specific precautions during design and maintenance.

Natural refrigerants

• Ammonia (R717): excellent energy efficiency, zero GWP, no impact on the ozone layer. It is toxic and flammable only at high concentrations, which is why it must be handled with care and with safe hydronic systems.
• Carbon dioxide (CO₂, R744): negligible GWP, non-toxic and non-flammable, but requires systems designed to operate at very high pressures.
• Propane (R290): excellent efficiency, very low GWP, but highly flammable. It is increasingly used in small systems and compact heat pumps.

Key parameters for choosing a refrigerant

When selecting a refrigerant, we recommend evaluating the following factors:

• Energy efficiency: depends on enthalpy and operating pressures. An efficient refrigerant reduces consumption and improves system performance.
• Safety: consider toxicity and flammability (ISO 817 classification: for example, A1 = non-toxic/non-flammable, A2L = slightly flammable, A3 = highly flammable, B = toxic).
• Environmental impact: the key parameter is GWP (Global Warming Potential). The lower it is, the lower the greenhouse effect.
• Regulatory compliance: verify that the refrigerant is permitted under current regulations (F-gas 2024/573), which set GWP limits and deadlines for the phase-out of the most impactful gases.
• Availability and costs: some natural refrigerants are readily available and cost-effective, while others require more advanced technologies.

The new F-gas Regulation 2024/573: what changes?

European legislation is becoming increasingly stringent. The new F-Gas Regulation 2024/573 aims to drastically reduce fluorinated gas emissions, with the objective of phasing out HFCs by 2050.

Key points include:

• Ban on gases with GWP > 2500 for new installations and maintenance already in force since 2020.
• GWP limit of 750 for residential air conditioners from 2025; this excludes the use of R410A in new systems and will significantly restrict R32 in the coming years.
• Mandatory progressive reduction of HFC quotas placed on the market.
• Safety classification according to ISO 817:2014: each refrigerant is classified according to toxicity and flammability (A1, A2L, A3, B1, etc.).

For designers and installers, staying up to date is essential: choosing a refrigerant today must take into account not only performance, but also its “remaining lifespan” on the market.

Which refrigerants are used today in heat pumps

The heat pump market is rapidly adapting to new rules and the need for efficiency and sustainability.

Below is an overview of the main solutions:

In recent years, low-GWP refrigerants such as R454B, R454C and R290 have been gaining ground, while R410A and R32 are set for a gradual phase-out.

Why does Robur use ammonia?

Robur has chosen to use ammonia (R717) as the refrigerant in its absorption heat pumps for several reasons:

• Zero climate impact: ammonia has a GWP of zero and therefore does not contribute to the greenhouse effect.
• Excellent thermodynamic performance: it ensures high efficiency and reduced refrigerant charges, thanks to its high latent heat.
• Safety in hydronic solutions: in Robur products, the refrigeration circuit is completely separated from the system water, eliminating risks for users and environments.
• Regulatory stability: ammonia, as a natural refrigerant, is not subject to restrictions or phase-outs foreseen for HFCs and HFOs. This makes it a safe and future-proof choice.

Thanks to these characteristics, Robur heat pumps offer a robust, eco-friendly solution that complies with the most up-to-date regulations, ideal for those seeking efficiency and sustainability without compromise.

Conclusion

Today, choosing a refrigerant is a strategic decision that goes far beyond simple efficiency. Safety, environmental impact, regulatory compliance and long-term prospects must all be taken into account.

The HVAC sector is moving towards natural and low-GWP refrigerants, with a strong acceleration driven by the new F-gas regulation.

Robur, thanks to the use of ammonia in its gas heat pumps, provides a concrete and reliable answer to today’s and tomorrow’s challenges: efficient, safe, sustainable products that are ready for the future of air conditioning.

If you would like to learn more about Robur solutions or need support in choosing the most suitable refrigerant for your project, our technical team is always at your disposal.