Australia’s rail operators are facing a major challenge – the refrigerants that currently keep passengers cool are heading for extinction.
Under the Kigali Amendment, an international environmental agreement, potent greenhouse gases called Hydrofluorocarbons (HFCs) are being phased out.
Suppliers are already winding down stock and transitioning to alternatives with low Global Warming Potential (GWP).
For operators still reliant on legacy refrigerants for their air conditioning needs, the cost of inaction may not be immediate, but it will be steep.
“The writing is on the wall,” said Joshua Pitcher, Engineering Manager Heating, Ventilation and Air Conditioning (HVAC) at Knorr-Bremse Australia.
“Refrigerants like R407c and R134a, with high GWP, are going obsolete.
“If operators don’t act soon, they’ll be caught without parts, supply, or a plan.”
Understanding Kigali’s impact on rail
The Kigali Amendment is part of the Montreal Protocol – a landmark international agreement to protect the Earth’s ozone layer by phasing out the production and use of ozone-depleting substances, particularly chlorofluorocarbons (CFCs).
The Montreal Agreement was signed in 1987 and subsequently ratified by 198 nations.
“Today we see the ozone layer shrinking and healing, and the latest predictions are that it will close within our lifetimes,” said Pitcher.
“It’s considered to be one of the most successful environmental agreements in history.”
Following this success, member states met in 2016 to draft the Kigali Amendment, which aims to reduce worldwide HFC use.
“HFCs can be thousands of times more potent than carbon dioxide as greenhouse gases,” said Pitcher.
“To put it into perspective, just one kilogram of F407c, a popular refrigerant used in rail, has a greater greenhouse impact than the annual usage of the average small-to-mid-size car!”
To maximise the benefits of reduced greenhouse gases, Australia has committed to an aggressive reduction target in the short-term, cutting HFC imports by more than two-thirds by 2026.
That will pose problems for the rail sector, where air conditioning systems completely rely on imported refrigerants.
“We don’t make refrigerants in Australia,” Pitcher explained. “We import 100 per cent of them, and the government is reducing how much global warming potential can be imported each year. This isn’t just about environmental policy; it’s a supply issue.”
And supply is already tightening. European markets, which entered the phase-down earlier than Australia, have experienced steep price spikes.
“The price of some refrigerants initially jumped tenfold in Europe,” Pitcher said. “Australia may see the same if we’re not ready.”
It’s not just about swapping gases
Replacing train air conditioning refrigerants isn’t always straightforward. While some legacy systems can transition to low-GWP alternatives with minimal changes required, others require reengineering.
R134a systems, for example, can often be adapted to use R513a, a non-flammable refrigerant with around one-third the global warming potential. But R407c has no such non-flammable equivalent.
“That’s where it gets tricky,” said Pitcher. “To move away from R407c, you need to embrace low-flammability refrigerants.”
This has raised safety concerns across the rail industry. Trains carry large volumes of refrigerant and transport hundreds of passengers, which makes flammability a sensitive issue.
“Operators are cautious, naturally,” Pitcher said. “But low-flammability refrigerants require extremely specific conditions to ignite.
“They don’t spark like propane on a barbecue. You’d need a perfect storm of high concentration, a flame, and containment for them to pose a risk. In most real-world scenarios, that just doesn’t happen.”
He added that Knorr-Bremse’s latest designs, available through its HVAC technology brand Merak, account for these factors.
“We’ve engineered systems where risks are actively mitigated. If the refrigerant leaks, it will dilute externally to a non-flammable level very quickly. Leaks within the passenger areas are eliminated through design. Even if it does catch fire, the propagation of the flame is very slight. It’s basically self-extinguishing and not explosive like propane.”
Obsolescence is already underway
Pitcher said that if operators think stockpiling HFCs is a solution, they should think again.
“Even if you’ve got ten years’ worth of refrigerant in storage, it won’t matter if your compressor breaks and the replacement part is no longer being made,” Pitcher said.
Brett Barty, Head of Business Development at Knorr-Bremse, said component manufacturers are also transitioning away from HFC-compatible systems.
“We’re already seeing component suppliers shut down product lines tied to legacy refrigerants,” he said.
“They’re future-proofing their own operations, which means old systems will become increasingly unserviceable.”
Train HVAC systems are designed to last 30 years or more, and ongoing parts support is essential. However, as the refrigerant supply shrinks, so does the supply chain for compatible components.
“The whole ecosystem is shifting,” Barty said. “Refrigerants, compressors, seals, valves – it all has to evolve together.”
Timing is everything
The key to managing this transition is synchronisation. HVAC systems undergo major overhauls every eight to 12 years, presenting an ideal refrigerant conversion opportunity.
“If you time it with your scheduled maintenance, you can minimise cost and disruption,” Pitcher said.
“Instead of swapping a compressor for a like-for-like unit, you replace it with one suitable for a new refrigerant.
“The price may be comparable, and you’re doing the work anyway.”
Failing to plan could mean doubling up on costs or worse – missing critical maintenance windows and grounding trains.
“You don’t want air conditioners sitting on pallets in a depot because the refrigerant or compressor is unavailable,” Barty said.
“We’ve seen what happens when supply chains break down. In rail, that leads to delays, cancellations, and unhappy passengers.”
Lessons from Europe, solutions from Australia
Europe’s rail sector is ahead of the curve, with Knorr-Bremse’s HVAC team in Spain already delivering propane-based systems to operators such as Deutsche Bahn in Germany. These units have passed strict safety audits and deliver energy efficiency gains.
“Propane is one of the best refrigerants available in terms of performance,” Pitcher said. “With proper engineering controls, it’s also safe.”
Knorr-Bremse is also exploring tropical-rated carbon dioxide (CO₂) refrigerant systems, which are currently being trialled in Southeast Asia. These systems will be suitable for humid environments such as northern Australia.
“CO₂ is perfect for temperate climates and offers added benefits as a heat pump,” Pitcher explained. “In Europe, where heating demand is high, that’s a big advantage.”
The Australian market needs solutions suited to its extremes, and Knorr-Bremse’s team is working closely with operators to assess which refrigerants will work best in Queensland, Victoria, and Western Australia.
“No two cities are the same,” Pitcher said. “What works in Vancouver won’t necessarily work in Sydney. That’s why customisation matters.”
Breaking through industry inertia
Despite growing urgency, the industry remains slow to act. Barty said one of the biggest challenges is the culture of waiting.
“There’s a tendency in rail to see who moves first,” he said. “No one wants to be the test case. But that hesitation creates real risk.”
Barty added that engineering resources could run dry if too many operators delay their transition.
Operators need to act now to develop tailored strategies, secure parts, and schedule upgrades during existing maintenance windows.
“There’s only so much capacity in the system. If everyone waits until 2026 to start planning, we won’t have enough people to do the work.
“You can’t retrofit an entire HVAC fleet overnight,” Barty said. “This has to be staged, planned, and resourced.”
A global company with local solutions
Knorr-Bremse’s HVAC design centre in Australia plays a key role in delivering solutions locally and across North America, Asia, and the Middle East.
“We might be based in Australia, but our designs are used globally,” Pitcher said. “That means we can draw from a wide range of data, environments, and use cases to deliver refrigerant solutions that actually work.”
The company has been engaging with operators across Australia to present options, validate system performance, and conduct risk assessments that satisfy engineers and asset managers.
“Our goal is to help operators make informed decisions,” Pitcher said. “That means backing up every recommendation with modelling, trials, and transparent communication.
“If we align refrigerant transitions with scheduled maintenance, we can reduce cost, minimise disruption, and future-proof Australia’s rolling stock.”