28
Feature
THE RISE OF NATURAL REFRIGERANTS Visser provided evidence of natural refrigerants ' widespread adoption, particularly in Europe, where there are " 90 700 transcritical CO₂ supermarkets— around one in three stores— and more than 17 million hydrocarbon plug-in cabinets, most running on R-290." North America and Japan are also seeing significant growth.
Closer to home, Visser shared data from FRIGAIR 2024, revealing " ≈ 350 CO₂ transcritical supermarkets up from just 50 five years ago " in South Africa. He added, " Hydrocarbons are spreading even faster: an estimated 51 000 R-290 cabinets... are now in service nationwide. Almost every supermarket is converting freezer and beverage aisles to R-290 plug-ins during every major remodel." He also noted the emergence of low-charge NH₃ / CO₂ distribution hubs commissioned in 2023 – 24 for industrial users.
Visser presented a case study of a 2 500m ² supermarket, demonstrating that a legacy R-404A system " drew 33 % more than a modern transcritical CO₂ rack." He highlighted CO₂ ' s GWP of 1, making leaks " virtually climate-neutral and Kigali-compliant today ".
For propane( R-290) plug-in retail cabinets, Visser celebrated the 2022 update to IEC 60335-2-89, which lifted the hydrocarbon charge limit to 500g per sealed circuit, making almost all cabinet formats R-290-compatible. He stated that field trials show 30 – 50 % lower kWh than identical HFC units with R-290, leading to a TEWI shrinks by ~ 70 % versus legacy HFC cabinets. Visser noted, " Propane is no longer only a solution for small beverage coolers and freezers, it can be used as a solution for the entire store, including cold and freezer rooms."
THE ROLE OF LOW-GWP SYNTHETICS: HFOS AND BLENDS
Acknowledging that " naturals aren’ t always feasible— think split AC units on the 30th floor," Visser introduced low-GWP hydrofluoroolefins( HFOs) and their blends. He noted that " pure R-1234yf clocks a GWP of 4— a 99 % cut from R-134a." Blends like R-454C( GWP 148) or R-452B( GWP 676) offer significant GWP reductions without major hardware changes. While these are A2L( mildly flammable), Visser assured that " technician upskilling is the gating item, not the compressor design ".
He described HFOs and blends, as: " The pragmatic bridge with big GWP cuts now, manageable safety tweaks— buying time until naturals or solid-state cooling cover every application."
EMERGING CONCERN: TFA & PFAS DEBATE Visser addressed a growing concern with HFOs: their breakdown into trifluoroacetic acid( TFA). He explained, " Atmospheric oxidation of HFO-1234yf yields TFA with ~ 100 % molar efficiency. The acid is highly persistent and water-soluble. While the UNEP Environmental Effects Panel 2024 calls current human-health risk low, the EU Chemicals Agency’ s draft PFAS restriction could capture all fluorinated refrigerants that create persistent degradation products— including TFA."
His advice to companies was to " diversify portfolios— keep natural refrigerant options ready— and stay engaged in standards work shaping allowable emissions ". He added: " Low-GWP synthetics solve today’ s carbon problem, but TFA reminds us that no refrigerant is impact-free— continuous vigilance is part of responsible engineering."
SELECTING THE RIGHT REFRIGERANT: PRACTICAL DECISION RULES
Visser presented a decision framework based on " four gates: capacity, policy, safety, economics."
• Capacity: " Plug-in units hydrocarbons or HFO-1234yf work well. Medium supermarket remote racks CO₂ or low-GWP A2L blends.
Large industrial loads low-charge ammonia or CO₂ cascade."
• Policy compliance: " EU and US bans push new commercial systems to under 150 GWP from 2025. Anything above that is short-lived."
• Safety class: From A1( non-flammable) to B2( toxic), he stressed that " A3 = high flammability— great for sealed plug-in cabinets, and with regulation updates, applicable to full store supermarkets."
• Cost and skills:“ While CO₂ racks cost approximately 10 % more up front; propane cabinets do not. What refrigerant is best for my climate, and what technicians do I have available to service the refrigerant I select, are considerations."
Visser urged, " Always aim for the greenest fluid that your safety codes, skill set and budget can handle— that simple hierarchy locks in climate gains without compromising operations."
Looking to the future, Visser explored technologies aiming to eliminate refrigerants and compressors entirely. He highlighted, " Thermoelectrics, currently a niche but showing promise, with a 2024 field trial cooling a server pod with no moving parts, hitting COP of approximately 2 at 30 ° C ambient."
He also discussed‘ Radiative and other passive systems’, such as " spectrally selective films emit heat to outer space even under sunlight, with test roofs showing 4 – 6 ° C below ambient ". Another exciting area is solid-state caloric cooling, where materials shift temperature when a field or stress is applied, with a 2023 EU demo producing 1.8 kW at COP of approximately 3.2 using aluminum gallium alloy and no refrigerant.
Visser projected that " solid-state modules would enter mini-fridges and telecom enclosures by 2030; light-commercial splits by mid-2030s, with combined passive and caloric share potentially topping 10 % of global cooling capacity by 2045 ". He pointed out South Africa ' s suitability for radiative panels due to its " high-solar, low-humidity regions ". His final thought on this topic was: " Keep an eye on solid-state and passive hybrids— they could bypass refrigerant debates entirely and reshape cooling within two decades."
KEY TAKE-AWAYS Visser concluded his presentation with a summary of key takeaways:
• " Rising cooling demand of 1 000 TWh extra by 2035— makes refrigerant decisions a frontline climate lever."
• " Kigali cuts HFC production 85 % by 2047."
• " EU F-gas and US AIM Act ban over 150-GWP refrigerants in new commercial systems from 2025 – 27; South Africa’ s phase-down mirrors that timeline."
• " Naturals already dominate EU supermarkets: 90 700 CO₂ stores, 17 million R-290 cabinets."
• " SA retail now runs approximately 350 CO₂ supermarkets and 51 000 propane plug-ins— technology and skills exist locally."
• " A2L HFO blends slash GWP 65 – 99 % and fit existing hardware but produce TFA; regulators are watching PFAS impact, so we need to keep our options open."
• " A fluid is‘ green’ only if your technicians can handle its pressure or flammability safely. Up-skilling and leak-detection upgrades will make a lasting impact in our market."
• " Choose the lowest-GWP refrigerant that clears policy, safety and economic gates for your application. Do it now— retrofits later cost more."
THE POTENTIAL OF CO₂ IN HVAC With a remarkably low Global Warming Potential( GWP) of just one, CO₂ has emerged as a leading refrigerant in the cooling industry, offering a
28
RACA Journal I August 2025 www. refrigerationandaircon. co. za