R32 vs R454B: choosing a refrigerant on a 2026 commercial AC replacement

Why refrigerant is now a purchase decision

For most of the last two decades refrigerant was something the installer dealt with. That changed when the GB F-Gas regime moved to a quota-based phase-down: rather than banning gases outright, it steadily reduces the total tonnage of CO₂-equivalent HFC that can be placed on the market.

The effect is economic rather than legal. High-GWP gases consume quota disproportionately — a kilogram of R410A eats roughly twenty times the quota of a kilogram of R32 measured in CO₂e — so suppliers allocate away from them and prices rise well before any ban. A system charged with an obsolescent refrigerant therefore carries a higher lifetime cost than its purchase price suggests, because every future leak repair buys gas from a shrinking, more expensive pool.

That is why the gas in a system you are buying in 2026 is worth thinking about, and it is the background to our air conditioning replacement page.

The two candidates

R32

A single-component refrigerant with a GWP of 675. Because it is not a blend it does not suffer temperature glide, which makes charging and servicing more straightforward — you can top up a system without recovering the whole charge, which matters for maintenance cost over a fifteen-year life. It has been the mainstream replacement for R410A in smaller and mid-size equipment for several years, so the equipment range and engineer familiarity are both broad.

R454B

A blend with a GWP of around 466 — meaningfully lower than R32. It has been adopted widely in larger commercial equipment, particularly where manufacturers wanted a drop further down the GWP scale without moving to a natural refrigerant. Being a blend, it has some temperature glide, which has practical implications for charging and for how a partial loss is dealt with.

For completeness, R290 (propane, GWP 3) appears on smaller duties. It is an A3 refrigerant — properly flammable rather than mildly so — which brings DSEAR into play alongside BS EN 378 and constrains where it can be used.

What actually decides it

The GWP difference between R32 and R454B is real but it is rarely the deciding factor, for a simple reason: you are usually choosing equipment, not refrigerant. Manufacturers select the gas for a given range, so the practical question is which units suit the building — and the refrigerant follows.

Where the choice genuinely is open, these are the considerations that matter more than the GWP number:

• Charge limits. Both are A2L, and BS EN 378 caps charge against the volume of the smallest room served. The permitted charge differs between the two gases, so on a building of small rooms this can decide the answer outright.
• F-Gas leak-check band. Checking frequency is set by charge in tonnes of CO₂e, at the 5, 50 and 500 tonne thresholds. A lower-GWP gas gives a lower tCO₂e figure for the same physical charge, which can drop a system into a less frequent checking band — a permanent reduction in compliance cost that almost never appears in a business case.
• Servicing practicality. A single-component gas is simpler to top up than a blend with glide. Over a long service life this is a real, if unglamorous, cost difference.
• Availability and support. Which gas your maintenance contractor stocks and is certified for, and how easily parts and gas can be sourced locally.

The A2L constraint that catches replacements

This is the part that turns a procurement exercise into a design exercise, and it is the most common technical omission we see in replacement proposals.

Because both gases are mildly flammable, BS EN 378 limits the refrigerant charge relative to the volume of the smallest occupied room the system serves. An old R410A system serving several small rooms — individual offices, hotel bedrooms, treatment rooms, small meeting rooms — may not be replaceable with an equivalent-duty A2L system on the same architecture, because the required charge would exceed what the smallest room allows.

The ways round it are genuine engineering choices with cost implications: split the system into more, smaller circuits; relocate or reconfigure indoor units; add mechanical ventilation or refrigerant leak detection with interlocks to permit a higher charge; or change system type entirely — which is one reason chilled water becomes attractive in buildings with many small rooms, since it keeps refrigerant in the plant room.

If a replacement quote for a multi-room building makes no mention of charge limits, ask about them before comparing prices.

What about the system you already have?

R22 has been banned for servicing use since 2015, including recycled gas. An R22 system can keep running while it is sealed, and repairs not involving refrigerant are still possible, but any significant loss ends it — there is no compliant way to recharge. That is an asset with no failure tolerance, and it is worth converting into a budget line rather than a risk.

R410A is not banned and there is no cliff-edge date. What changes is the arithmetic: as recharging gets more expensive, the "repair the leak and top it up" option tips toward replacement earlier than it used to. See repair versus replace.

One thing that is not an option: dropping a new gas into an old system. Beyond the safety and charge-limit issues, R22 systems used mineral oil while modern systems use POE, and the two are incompatible — residual mineral oil causes oil starvation and early compressor failure. Reused pipework must be chemically flushed and verified, or replaced.

Regulatory detail moves. Confirm the current position on GOV.UK and via REFCOM before it drives a purchase, and see our F-Gas regulations guide.

Frequently asked questions

Is R32 or R454B better?

Neither is universally better. R454B has the lower GWP at around 466 against R32's 675, but R32 is a single-component gas with no temperature glide, which makes charging and topping up simpler over a long service life. In practice you are usually choosing equipment rather than refrigerant, and the charge limits for the rooms being served matter more than the GWP difference.

Can I just put R32 into my existing R410A system?

No. Beyond the pressure and component differences, R32 is A2L — mildly flammable — so the system must be designed and installed for it, including charge limits assessed against the smallest room served. Replacement means new equipment, and where pipework is reused it must be checked for sizing, pressure rating, condition and oil compatibility.

Does a lower-GWP refrigerant reduce my compliance burden?

It can. F-Gas leak-check frequency is set by the charge expressed in tonnes of CO2 equivalent, so a lower-GWP gas gives a lower figure for the same physical charge and may place the system in a less frequent checking band. That is an ongoing saving in both engineer time and administration, and it is routinely left out of replacement business cases.

Why does my quote say the system has to be split into more circuits?

Almost certainly A2L charge limits. BS EN 378 caps refrigerant charge against the volume of the smallest room a system serves, so a design covering several small rooms may exceed the permitted charge on a single circuit. Splitting it, reconfiguring indoor units, adding leak detection, or moving to chilled water are the usual ways round it.

See air conditioning replacement for the full replacement picture, commercial air conditioning for system selection, and costs for indicative pricing.