Air-cycle refrigerants:<\/strong> air, commonly identified as R729 in refrigerant nomenclature<\/li>\n<\/ul>\nNatural refrigerant is an industry and technical term. It is not a single safety or efficiency classification. Different natural refrigerants have very different operating characteristics.<\/p>\n
What natural refrigerants are not<\/strong><\/p>\nA natural refrigerant is not automatically:<\/p>\n
\n- Non-flammable<\/li>\n
- Non-toxic<\/li>\n
- Suitable for every building<\/li>\n
- More efficient in every operating condition<\/li>\n
- Compatible with existing compressors or pipework<\/li>\n
- Safe for a refrigerant conversion<\/li>\n
- A guarantee of low electricity consumption<\/li>\n<\/ul>\n
The complete heat pump must be designed around the selected refrigerant. The compressor, heat exchangers, expansion device, seals, lubricant, pipework, pressure controls, electrical components, enclosure, and safety system must all be compatible.<\/p>\n
<\/span>Core Purpose of Natural Refrigerants<\/span><\/h2>\nThe core purpose of a natural refrigerant is to transport thermal energy through the heat-pump cycle. It enables a heat pump to collect low-temperature heat and deliver that heat at a useful temperature.<\/p>\n
Natural refrigerants perform the same basic thermodynamic function as fluorinated refrigerants. Their main difference lies in their chemistry, climate impact, safety characteristics, operating pressure, and regulatory treatment.<\/p>\n
How the natural refrigerant cycle works<\/strong><\/p>\n\n- Evaporation absorbs heat.<\/strong>
The refrigerant enters the evaporator at low pressure. It absorbs energy from outdoor air, ground, groundwater, or waste heat.<\/li>\n- Compression raises the temperature.<\/strong>
The compressor increases the refrigerant pressure. This process also raises its temperature.<\/li>\n- Heat transfer releases useful energy.<\/strong>
The refrigerant transfers heat to the building\u2019s heating water or domestic hot water. Most heat pumps use a condenser. Transcritical carbon dioxide systems often use a gas cooler instead.<\/li>\n- Expansion lowers the pressure.<\/strong>
The expansion device reduces the refrigerant pressure and temperature. The cycle then starts again.<\/li>\n<\/ol>\nEvaporation requires heat input, while compression raises the refrigerant to a temperature that can serve the building. This principle applies to both natural and fluorinated refrigerants.<\/p>\n
Environmental purpose<\/strong><\/p>\nNatural refrigerants provide a route away from high-global-warming-potential fluorinated gases. Their low direct climate impact becomes relevant when refrigerant escapes from the system.<\/p>\n
Regulatory purpose<\/strong><\/p>\nNatural refrigerants help manufacturers and building owners prepare for restrictions on fluorinated refrigerants. They can support long-term product availability and asset planning.<\/p>\n
Operational purpose<\/strong><\/p>\nEach natural refrigerant supports different operating conditions. R290 is widely used in building heat pumps. R744 can suit high domestic-hot-water demand. R717 is established in large industrial systems.<\/p>\n
<\/span>Why Natural Refrigerants Are Needed<\/span><\/h2>\nThe direct-emissions problem<\/h3>\n
A heat pump transfers environmental heat without combustion at the building. However, a refrigerant leak can create direct greenhouse gas emissions.<\/p>\n
The scale of those emissions depends on:<\/p>\n
\n- Refrigerant type<\/li>\n
- Refrigerant charge<\/li>\n
- GWP value<\/li>\n
- Leakage rate<\/li>\n
- Service losses<\/li>\n
- Refrigerant recovery at end of life<\/li>\n<\/ul>\n
A small leak of a high-GWP refrigerant can represent a significant quantity of carbon dioxide equivalent. Natural refrigerants normally have a GWP close to zero or, in the case of carbon dioxide, a reference GWP of one.<\/p>\n
The regulatory problem<\/h3>\n
Regulation (EU) 2024\/573 entered into force on 11 March 2024. It introduced a stronger HFC phase-down and a staged schedule of restrictions for new refrigeration, air-conditioning, and heat-pump equipment. The rules apply directly in Austria, Germany, Italy, Spain, Poland, Finland, and other EU Member States.<\/p>\n
Important heat-pump milestones include the following:<\/p>\n<\/div>\n
\n
\n\n\n| Equipment category<\/th>\n | EU restriction, subject to stated safety exceptions<\/th>\n<\/tr>\n<\/thead>\n |
\n\n| Self-contained heat pumps up to and including 12 kW<\/td>\n | F-gases with GWP of 150 or more prohibited from 1 January 2027<\/td>\n<\/tr>\n |
\n| Self-contained heat pumps up to and including 12 kW<\/td>\n | F-gases generally prohibited from 1 January 2032<\/td>\n<\/tr>\n |
\n| Self-contained equipment above 12 kW and up to 50 kW<\/td>\n | F-gases with GWP of 150 or more prohibited from 1 January 2027<\/td>\n<\/tr>\n |
\n| Other self-contained heat pumps<\/td>\n | F-gases with GWP of 150 or more prohibited from 1 January 2030<\/td>\n<\/tr>\n |
\n| Split air-to-water systems up to and including 12 kW<\/td>\n | F-gases with GWP of 150 or more prohibited from 1 January 2027<\/td>\n<\/tr>\n |
\n| Split air-to-air systems up to and including 12 kW<\/td>\n | F-gases with GWP of 150 or more prohibited from 1 January 2029<\/td>\n<\/tr>\n |
\n| Split systems up to and including 12 kW<\/td>\n | F-gases generally prohibited from 1 January 2035<\/td>\n<\/tr>\n |
\n| Split systems above 12 kW<\/td>\n | F-gases with GWP of 750 or more prohibited from 1 January 2029<\/td>\n<\/tr>\n |
\n| Split systems above 12 kW<\/td>\n | F-gases with GWP of 150 or more prohibited from 1 January 2033<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\nThese dates concern the placing of new equipment on the market. They do not automatically require every installed heat pump to stop operating on the relevant date. Servicing restrictions, refrigerant availability, equipment condition, and national obligations must be assessed separately. The regulation also includes safety-related exceptions under defined conditions.<\/p>\n Because natural refrigerants are non-fluorinated, they are not part of the HFC quota phase-down. However, the heat pump remains subject to product safety, electrical safety, pressure, fire-safety, building, installation, and service requirements. EU certification rules now also cover relevant alternatives to F-gases, including natural refrigerants.<\/p>\n The Swiss regulatory context<\/h3>\nSwitzerland is not governed directly by the EU F-gas Regulation. Refrigerants are regulated through Annex 2.10 of the Swiss Chemical Risk Reduction Ordinance, known as ORRChem or ChemRRV.<\/p>\n The Swiss framework aims to reduce emissions from ozone-depleting and strongly climate-warming refrigerants. It is updated to follow technical progress and developments in European regulation. A project in Switzerland must therefore be checked against the current Swiss provisions rather than treated automatically as an EU project.<\/p>\n The business problem<\/h3>\nA heat pump is a long-life building asset. A refrigerant decision can affect service availability, repair costs, portfolio compliance, procurement criteria, and future replacement planning.<\/p>\n A poorly selected system can expose a building owner to:<\/p>\n \n- Restricted future product choices<\/li>\n
- Higher refrigerant costs<\/li>\n
- Limited service capacity<\/li>\n
- Difficult component replacement<\/li>\n
- Premature asset replacement<\/li>\n
- Safety-related installation changes<\/li>\n
- Failure to meet environmental procurement requirements<\/li>\n<\/ul>\n
Natural refrigerants can reduce some of these risks. They do not remove the need for correct system design.<\/p>\n The whole-system performance problem<\/h3>\nA low-GWP refrigerant does not compensate for poor sizing, high flow temperatures, excessive cycling, weak insulation, or inefficient controls. The heat pump\u2019s electricity use must be assessed alongside direct refrigerant emissions.<\/p>\n The correct goal is not simply to select the refrigerant with the lowest GWP. The goal is to select a safe, efficient, serviceable, and regulation-ready heat-pump system.<\/p>\n <\/span>Key Features of Natural Refrigerants<\/span><\/h2>\n<\/div>\n\n \n\n\n| Feature<\/th>\n | Meaning<\/th>\n | Practical decision<\/th>\n<\/tr>\n<\/thead>\n | \n\n| Non-fluorinated chemistry<\/td>\n | The substance does not belong to the HFC or HFO refrigerant families<\/td>\n | Reduces exposure to the HFC quota phase-down<\/td>\n<\/tr>\n | \n| Very low GWP<\/td>\n | Leakage creates little direct carbon dioxide equivalent compared with high-GWP refrigerants<\/td>\n | Supports lower direct climate impact<\/td>\n<\/tr>\n | \n| Zero ozone-depletion potential<\/td>\n | The refrigerant does not damage stratospheric ozone<\/td>\n | Avoids the ozone risks associated with older CFC and HCFC refrigerants<\/td>\n<\/tr>\n | \n| Defined safety class<\/td>\n | Toxicity and flammability differ by substance<\/td>\n | Determines charge, siting, ventilation, and component requirements<\/td>\n<\/tr>\n | \n| Refrigerant-specific pressure<\/td>\n | Each substance operates at a different pressure range<\/td>\n | Determines compressor, pipe, vessel, and control design<\/td>\n<\/tr>\n | \n| Application-specific temperature range<\/td>\n | Different refrigerants suit different source and delivery temperatures<\/td>\n | Influences space heating, hot water, and process-heat suitability<\/td>\n<\/tr>\n | \n| Refrigerant charge<\/td>\n | The mass of refrigerant affects potential leak consequences<\/td>\n | Encourages compact circuits and controlled installation<\/td>\n<\/tr>\n | \n| System architecture<\/td>\n | The refrigerant may remain outdoors or circulate through field-installed pipework<\/td>\n | Influences monoblock, split, or secondary-circuit selection<\/td>\n<\/tr>\n | \n| Material compatibility<\/td>\n | Metals, seals, oils, and components must match the refrigerant<\/td>\n | Prevents degradation, leakage, and compressor damage<\/td>\n<\/tr>\n | \n| Qualified handling<\/td>\n | Installation and service require suitable competence<\/td>\n | Protects occupants, technicians, equipment, and the environment<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/span>Detailed Explanation of Natural Refrigerant Features<\/span><\/h2>\nNon-fluorinated composition<\/h3>\nDefinition:<\/strong>
A non-fluorinated refrigerant does not contain fluorine as part of an HFC or HFO refrigerant molecule. Natural refrigerants include hydrocarbons and inorganic substances.<\/p>\nPurpose:<\/strong>
The composition separates these refrigerants from gases controlled through the EU HFC quota phase-down.<\/p>\nBenefits:<\/strong>
The system has less exposure to future HFC availability and quota-related market pressure. It also avoids direct emissions from high-GWP fluorinated gases.<\/p>\nExample:<\/strong>
R290 is a hydrocarbon refrigerant. It is used in factory-designed residential and commercial heat pumps.<\/p>\nVery low global warming potential<\/h3>\nDefinition:<\/strong>
Global warming potential compares the warming effect of a released substance with the effect of carbon dioxide over a defined period.<\/p>\nPurpose:<\/strong>
GWP allows planners to calculate direct refrigerant emissions as carbon dioxide equivalent.<\/p>\nBenefits:<\/strong>
A low-GWP refrigerant reduces the direct climate consequence of leakage. It can also support environmental procurement and carbon reporting.<\/p>\nExample:<\/strong>
Under the GWP values used by the European Commission for Regulation (EU) 2024\/573, R290 has a 100-year GWP of 0.02. R744 has a GWP of 1. Older documents may show different values because they use earlier scientific assessment reports.<\/p>\nZero ozone-depletion potential<\/h3>\nDefinition:<\/strong>
Ozone-depletion potential measures the ability of a substance to damage the stratospheric ozone layer.<\/p>\nPurpose:<\/strong>
The metric distinguishes modern refrigerants from older CFC and HCFC substances such as R12 and R22.<\/p>\nBenefits:<\/strong>
Natural refrigerants such as R290, R744, R717, R600a, and R718 have no ozone-depletion effect.<\/p>\nExample:<\/strong>
Selecting an R290 heat pump avoids both the ozone impact of older refrigerants and the high direct climate impact of many legacy HFCs.<\/p>\nSafety classification<\/h3>\nDefinition:<\/strong>
ISO 817 classifies refrigerants according to toxicity and flammability. The letter indicates toxicity class. The number indicates flammability class.<\/p>\n\n- A:<\/strong> Lower toxicity<\/li>\n
- B:<\/strong> Higher toxicity<\/li>\n
- 1:<\/strong> No flame propagation under the standard test<\/li>\n
- 2L:<\/strong> Lower flammability with low burning velocity<\/li>\n
- 2:<\/strong> Lower flammability<\/li>\n
- 3:<\/strong> Higher flammability<\/li>\n<\/ul>\n
Purpose:<\/strong>
The safety class provides a common basis for equipment design, charge limits, room-volume calculations, installation conditions, and service procedures.<\/p>\nBenefits:<\/strong>
A clear classification allows manufacturers and installers to apply the correct risk controls.<\/p>\nExample:<\/strong>
R290 is A3 because it has lower toxicity and higher flammability. R744 is A1. R717 is B2L because ammonia has higher toxicity and lower flammability. A1 does not mean risk-free; pressure, asphyxiation, and confined-space risks can still apply.<\/p>\nPressure-temperature behaviour<\/h3>\nDefinition:<\/strong>
Each refrigerant has a specific relationship between pressure, temperature, density, and physical state.<\/p>\nPurpose:<\/strong>
This relationship determines the compressor design, heat-exchanger size, pipe strength, expansion control, and operating envelope.<\/p>\nBenefits:<\/strong>
A refrigerant matched to the application can transfer heat efficiently across the required temperature lift.<\/p>\nExample:<\/strong>
R744 operates at much higher pressure than most building heat-pump refrigerants. R718 can operate under vacuum and requires large refrigerant volume flow. These characteristics require purpose-built components rather than a simple fluid substitution.<\/p>\nTemperature capability<\/h3>\nDefinition:<\/strong>
Temperature capability describes the source and delivery temperatures within which the refrigerant circuit can operate safely and efficiently.<\/p>\nPurpose:<\/strong>
It determines whether the heat pump can serve underfloor heating, radiators, domestic hot water, industrial process heat, or district-heating networks.<\/p>\nBenefits:<\/strong>
Correct matching prevents excessive compressor stress and poor seasonal performance.<\/p>\nExample:<\/strong>
R290 is used in building heat pumps capable of elevated flow temperatures. R744 is established in domestic-hot-water and commercial applications. R717 is frequently used in medium and large industrial systems. Actual temperature limits remain product-specific.<\/p>\nEnergy efficiency<\/h3>\nDefinition:<\/strong>
Energy efficiency measures how much useful heat the heat pump delivers for each unit of electrical energy consumed.<\/p>\nPurpose:<\/strong>
Efficiency determines operating costs, grid demand, and most of the indirect climate impact.<\/p>\nBenefits:<\/strong>
A well-designed natural-refrigerant heat pump can combine low direct emissions with low electricity use.<\/p>\nExample:<\/strong>
Two R290 heat pumps can have different seasonal efficiencies because they use different compressors, heat exchangers, defrost strategies, controls, and hydraulic designs. Refrigerant identity alone does not determine the SCOP.<\/p>\nRefrigerant charge and containment<\/h3>\nDefinition:<\/strong>
Refrigerant charge is the mass of refrigerant contained in the heat-pump circuit.<\/p>\nPurpose:<\/strong>
Charge control limits the possible consequences of a leak. Compact heat exchangers, short circuits, factory joints, and hermetic components can reduce the required charge.<\/p>\nBenefits:<\/strong> | |