Natural refrigerants: mature technologies, but the crux is diffusion

Refrigeration's transition to climate-friendly solutions no longer depends solely on technology availability. CO₂, propane, ammonia, and other natural refrigerants are already used in a growing number of HVACR applications, and the technical solutions available today could cover up to 99.9% of the industry's applications.

An important change is highlighted: the main obstacle to the diffusion of natural refrigerants would no longer be only technological, but would above all concern skills, knowledge of available solutions, market acceptance and the ability to install them correctly .

This is a particularly timely issue for Europe. The F-Gas Regulation 2024/573 is progressively restricting the use of fluorinated gases and explicitly recognizes non-fluorinated alternatives such as CO₂, ammonia, hydrocarbons, water, and air for various refrigeration, air conditioning, and heat pump applications.

Natural Refrigerants: Ever-Expanding Applications in HVACR

There is no single natural refrigerant suitable for all applications . The transition is instead based on the ability to choose the most appropriate fluid based on temperatures, power, system configuration, installation location, and safety requirements.

In European commercial refrigeration , for example, the Commission already identifies R290, R600a, and R744 as the main non-fluorinated alternatives. Hydrocarbons are widely used in stand-alone equipment, while transcritical CO₂ systems have become established, especially in supermarkets and centralized installations.

The possibilities are further expanded in industrial refrigeration and heat pumps. Among the alternatives recognized at the European level are:

• CO₂ (R744) , used in commercial refrigeration, heat pumps and other applications;
• propane (R290) , increasingly present in self-contained appliances and heat pumps;
• ammonia (R717) , historically widespread in industrial refrigeration and also usable in industrial heat pumps;
• isobutane (R600a) , consolidated especially in domestic refrigeration and small-scale appliances;
• water and air , usable in specific applications.

This doesn't mean that every technology can be automatically transferred from one application to another. Fluid properties, in fact, require different design solutions.

Safety and design remain key

The low GWP does not eliminate technical issues. Propane is classified as A3, therefore highly flammable; ammonia requires special attention for toxicity and safety; CO₂ operates at significantly higher operating pressures than many traditional synthetic refrigerants.

For this reason, the diffusion of natural refrigerants requires specific design and not a simple replacement of the fluid inside equipment designed for other substances.

Among others, the following must be evaluated :

• amount of refrigerant;
• size and characteristics of the rooms;
• ventilation systems;
• leak detection;
• design pressure;
• compatible components and tools;
• maintenance procedures;
• staff training.

Technology maturity must therefore be distinguished from ease of implementation. A solution may be technically established but require different skills, components, and procedures than those traditionally used.

Precisely for this reason, the new European F-Gas Regulation has expanded the certification and training system to include relevant alternatives to fluorinated gases and, where necessary, natural refrigerants. The required skills include installation, maintenance, repair, leak testing, and recovery.

The real bottleneck may be the availability of skills

Among the main obstacles to large-scale diffusion are the lack of qualified technicians and engineers , as well as a still insufficient knowledge of the technologies on the part of end users.

This is a particularly important topic because the F-Gas transition is simultaneously affecting several refrigerant families. In the coming years, a refrigeration engineer may find himself working on systems with traditional HFCs, A2L blends, CO₂, R290, and ammonia, each with different operating characteristics and requirements.

The goal cannot therefore be simply to increase the number of certified technicians, but to develop true multi-refrigerant expertise.

Training will increasingly need to include:

• risk assessment;
• procedures for flammable refrigerants;
• management of high pressure circuits;
• recovery and charging;
• leak detection;
• knowledge of different system architectures;
• commissioning and energy optimization.

In this sense, European regulation is not only acting through bans and GWP limits. It is also helping to change the professional profile required in the HVACR sector.

F-Gas accelerates the European transition

EU Regulation 2024/573 further reinforces this trend through a schedule of progressively more stringent restrictions for various categories of equipment.

In refrigeration, for example, from 2030 many new stationary appliances – with the exceptions provided for by the Regulation – will not be able to use fluorinated gases with a GWP equal to or greater than 150. Further restrictions are expected for various categories of air conditioning and heat pumps between 2027 and 2035.

The European Commission itself highlights that the transition to non-fluorinated alternatives has already occurred in numerous segments and provides the technically available options for each category of equipment.

The European challenge in the coming years could therefore be less about the question "is there an alternative refrigerant?" and more about the ability to correctly apply the most suitable solution.

CO₂, ammonia, and hydrocarbons do not represent a single technology destined to indiscriminately replace HFCs. Rather, they form a family of complementary solutions, requiring specific design, training, and expertise.

The transition to natural refrigerants therefore requires three closely related elements: available technology, regulations that encourage its adoption, and qualified personnel capable of using it safely and efficiently.