Refrigerant GWP Explained: A Ratio, Not a Product Rating

Global warming potential compares one gas against carbon dioxide. It states how much warming a kilogram of that gas causes over a stated period, beside a kilogram of carbon dioxide over the same period. Carbon dioxide is the divisor, so it sits at 1 in every published table.

A ratio behaves nothing like a rating. A rating implies a designed scale with a floor, a ceiling and a good end to aim at. This has none of those; it is arithmetic on a physical property, climbing as far as the chemistry carries it.

The figure is silent on most of what a buyer cares about. Flammability and toxicity are graded separately, in their own safety class, and nothing in the number describes how well the gas cools, what pressure it works at, or how much a system holds. Ozone depletion is a third index, measuring a different harm entirely.

GWP is a property of the substance, not of the machine on your ledge. A charge sealed inside a working circuit emits nothing, whatever its number; what converts the ratio into an emission is the mass that gets out.

Every GWP is quoted over a stated number of years, and changing them changes the answer. Take R32, listed as HFC-32 and fitted to most new household splits here. The IPCC Sixth Assessment Report gives it 2,690 over 20 years, 771 over 100 years, and 220 over 500 years: one gas, one report, three answers.

That spread comes out of how long each gas survives up there; the report puts R32's atmospheric lifetime at 5.4 years. Carbon dioxide is the yardstick, and much of any release is still working centuries later. Over a short window the fluorinated gas is mostly still present and the ratio runs high; widened, it has long since broken down while the denominator carries on, and the ratio collapses.

Picking the window is a choice about what to weigh, not a fact anybody found. Singapore settles that choice in law: its Environmental Protection and Management Act 1999 defines the term on a 100-year basis, setting one kilogram of a gas against one kilogram of carbon dioxide, using values NEA publishes.

Assessment reports move the numbers as well. The Fifth Assessment Report puts R32 at 677 over 100 years; the Sixth puts the same molecule at 771 over the same span. Nothing about the gas changed between those publications, only the measurement of it.

That gap is not academic here. 771 sits above the ceiling written for household aircon; 677 sits below it. NEA states that the values it works from align with the Fifth Assessment Report, and the statute points at the list the agency publishes. Two accurate sources can disagree by roughly a hundred points, and only one decides what may be supplied here.

From 1 October 2022, a household aircon may not be supplied in Singapore if its refrigerant carries a GWP above 750. That restriction lives in the same Act. It binds importers, manufacturers and sellers rather than owners. Supplying a regulated good that fails it carries a fine of up to $10,000 on conviction.

The ceiling reaches a defined class of machine, not a brand or a price band. NEA writes a household air-conditioner here as a single-phase, non-ducted room unit rated at 17.6 kW or lower, with variable refrigerant flow equipment left out. Ordinary household splits sit well inside that.

750 is not a national figure either. It is written per category, and the categories diverge sharply: a household refrigerator sits at 15 under the same scheme, as does an electrically driven water-cooled chiller of 1,055 kW or more. The number follows what the equipment is and how much gas it carries.

Nothing about the rule looks backwards: NEA is explicit that the restriction reaches new sale or supply from that date onward, and equipment already installed beforehand is untouched. Suppliers were given until 30 September 2023 to clear non-compliant stock, so no owner picked up a duty then.

A ceiling written as a number erases everything above it from new supply. Manufacturers do not argue with a threshold; they withdraw the ranges that fail and engineer around whatever clears. A shopper met all of that as a changed model line and an unfamiliar sticker, with no visible link to a government table.

The ratio accounts for what escapes, never for what the system consumes. A split system in a Singapore flat runs across much of the year, and the electricity behind that is a continuing cost for its service life. Refrigerant is a stock that counts only once it leaves the circuit, and which of the two ends up larger depends on how much gas gets out and how much power the machine draws.

The escaped weight is the term almost nobody quotes: GWP is stated per kilogram, so the real emission is leaked weight times the ratio. A circuit that holds its charge and is emptied into a recovery cylinder has released close to nothing; the same system losing gas yearly and vented on removal has released its charge several times over. Where an old charge ends up is covered separately.

Push back when a low GWP figure is offered as the environmental case for a purchase. It is one input, already constrained by law, and every model lawfully in front of you cleared the same bar. What separates two machines is the efficiency figure, capacity matched honestly to the room, and an installation tight enough not to leak.

Replacement is the argument to watch for, and none of this supports it. Building and disposing of a system carries its own cost, and the old charge is released only if somebody chooses to. Nothing in the ceiling asks an owner to do anything, and anybody using it to press for replacing a machine that still cools has travelled well past what the rule says.

For a purchase today the question has largely been answered before you walk in. Every household split that may lawfully be sold here sits under 750, so the gas is not a lever anybody pulls between two compliant models. Which gas a system can physically take is a separate question, answered elsewhere on this site.

Read GWP as a supply signal rather than a product feature. A gas sitting well above the current ceiling is one whose new production is being squeezed by international agreement, and that surfaces as price and waiting time on a refill. It reaches an owner at one moment: the day a sealed circuit is opened and refilled.

Holding a system on a heavier gas is not a problem on a schedule. A sealed charge emits nothing, and swapping out a working machine to change its gas carries costs of its own. What genuinely shifts is the arithmetic on one particular fault: once the circuit needs refilling, the gas going back in comes from a supply that keeps shrinking.

Ask which refrigerant the model uses, then ask for its number and its source. A seller who names the gas, states the GWP and can say which report and window produced it is describing something checkable. A figure with no report and no horizon behind it has not been sourced.

• •Ask which assessment report a quoted figure came from. The Fifth and Sixth disagree about the same molecules, and only one governs supply here.
• •Ask over how many years. A 20-year figure and a 100-year figure for one gas can differ more than threefold.
• •Treat the rule as a minimum, not a selling point. Every new household split on sale here already sits under the ceiling.
• •Ask what the system holds in kilograms, not only what gas. The ratio is per kilogram, so the charge weight is half the answer.
• •On an installed system, keep the attention on whether the circuit is tight. A charge that never escapes never becomes an emission.