Refrigerant Choices for Cold Rooms: R404A vs R507 vs R290

The Short Answer

R404A and R507 are both HFC blends that have powered the majority of Singapore's commercial cold rooms for the past two decades. They perform well and equipment is familiar to every technician in the market — but both carry a very high global warming potential (GWP), and both are now squarely in the path of Singapore's HFC phase-down under the Kigali Amendment. R290 (propane) is the low-GWP alternative gaining the most ground, offering excellent thermal efficiency at a GWP of roughly 3, but it is a flammable (A3) refrigerant that comes with charge limits and installation rules that not every project can accommodate.

If you're specifying a new cold room today, the honest answer is: don't default to R404A out of habit. Work out whether R290 fits your system size and layout first, because it's the refrigerant with the clearest runway under Singapore's regulatory direction. If it doesn't fit, a lower-GWP HFC blend is usually a better long-term bet than another R404A or R507 system.

R404A vs R507 vs R290 at a Glance

Property	R404A	R507	R290 (Propane)
Type	HFC blend	HFC blend (azeotropic)	Natural refrigerant (hydrocarbon)
GWP (approx.)	~3,900	~3,900	~3
Ozone depletion potential	0	0	0
Flammability class	A1 (non-flammable)	A1 (non-flammable)	A3 (highly flammable)
Typical temperature range	Low & medium temp	Low temp (freezer-focused)	Low & medium temp
Energy efficiency	Good	Good	Very good — often 5–10% better COP
Charge quantity limits	None specific to flammability	None specific to flammability	Limited by safety standard (see below)
Singapore regulatory direction	Under HFC licensing controls, phasing down	Under HFC licensing controls, phasing down	Favoured under low-GWP policy push

Why R404A and R507 Are Losing Ground

R404A and R507 share almost identical properties: both are HFC blends with a GWP in the range of roughly 3,900, both are non-flammable (A1), and both have been the default choice for low and medium temperature commercial refrigeration for years precisely because they're familiar, reliable and easy to service. R507 is azeotropic, meaning it behaves like a single substance with no temperature glide during phase change — some engineers prefer this consistency for tight-tolerance freezer applications, while R404A has a small glide that rarely matters in practice.

The problem isn't performance — it's regulatory direction. A GWP near 3,900 means one kilogram of leaked R404A has the same warming impact as roughly 3.9 tonnes of CO2. As Singapore's HFC licensing quota tightens under the Kigali schedule, high-GWP blends like these are the first refrigerants squeezed. New systems specified around R404A or R507 today risk facing higher gas costs and tighter servicing availability well before the equipment reaches the end of its mechanical life.

R290 (Propane): The Low-GWP Option Gaining Ground

R290 is a hydrocarbon refrigerant with a GWP of roughly 3 — over a thousand times lower than R404A — combined with genuinely strong thermodynamic efficiency that often translates into a measurably lower electricity bill for a comparably sized system. It's increasingly the specification of choice for new commercial refrigeration internationally, and Singapore's policy direction (including the 2022 ban on high-GWP refrigerant in single-phase household air conditioners and the Low-GWP Refrigerants Chillers grant introduced to support early adopters) points the same way for commercial cooling generally.

The catch is flammability. R290 is classified A3 — higher flammability — under the ASHRAE/ISO safety classification system, which means a system using it must be designed, charged and installed to a recognised safety standard. The commonly referenced standard for self-contained commercial refrigeration appliances, IEC 60335-2-89, permits charge sizes up to 500g in a self-contained unit (raised from an earlier 150g limit), provided the unit meets the compensating safety, ventilation and room-size requirements the standard sets out. Split systems remain capped at a much lower charge — commonly cited around 150g — because the refrigerant piping runs through occupied space rather than staying sealed inside one factory-built unit.

Choosing the Right Refrigerant for Your Cold Room

The right refrigerant depends on system size, layout and how the space will be used, not on which one is "greenest" in isolation:

• Small to mid-sized commercial cold rooms and self-contained units: R290 is usually worth specifying where the calculated charge fits within safety limits — lower running cost, strong regulatory position, and increasingly familiar to technicians in Singapore.
• Larger walk-in cold rooms and split systems: R290's charge and ventilation requirements often don't fit a single large room cleanly. A lower-GWP HFC/HFO blend (such as R448A or R449A) is frequently the more practical choice, offering a meaningfully lower GWP than R404A without the flammability design burden.
• Very large or multi-room cold storage facilities: A cascade system using CO2 (R744) for the low-temperature circuit is worth evaluating against continuing with R404A or R507 — higher upfront cost, but a near-zero GWP and strong long-term regulatory position.
• Existing R404A or R507 systems still within their service life: Continuing to service and top up is often the most economical near-term choice, but it's worth budgeting for the eventual transition as gas becomes scarcer and more expensive under the phase-down.

Retrofitting an Existing R404A or R507 System

Retrofitting isn't always a full system replacement. Drop-in or near-drop-in HFO blends like R448A and R449A can often replace R404A in an existing compressor and pipework with modest component changes — expansion valve recalibration, oil type checks, and gasket or seal compatibility review. A retrofit to R290, on the other hand, usually isn't a simple gas swap: the flammability safety requirements generally mean a new or heavily modified system rather than a retrofit of existing non-flammable-rated equipment.

Before committing to any refrigerant change, a proper retrofit assessment should check compressor manufacturer approval for the new gas, oil compatibility, and whether your existing pipework, valves and seals are rated for the replacement refrigerant's pressure and chemical profile. Getting this wrong causes leaks, compressor damage, and warranty issues — it's not a change to make without a qualified assessment first.

How We Help You Decide

Every cold room we design includes a refrigerant recommendation based on your room size, layout, budget and how the space will be used — weighing running cost, regulatory direction and servicing practicality rather than defaulting to whatever was used last time. We design, supply and install systems using both conventional HFC blends and R290 propane where it fits safely, and we handle retrofit assessments for existing R404A and R507 systems looking to transition ahead of the phase-down.