Refrigerant ODP explained: the test every gas now passes

The measure is a ratio built around one fixed point. CFC-11 was assigned the value 1, and every other substance is placed against it. UNEP describes the calculation as a steady-state ozone reduction per unit of mass released each year, taken relative to CFC-11.

Nobody handles the reference compound any more. CFC-11 was a foam agent and refrigerant that the Montreal Protocol removed from production decades ago. Its value stayed pinned at 1 regardless, because moving the anchor would break every figure already written into treaty annexes and national registers.

A score of zero says something narrow and precise. It says the substance carries none of the chemistry that attacks ozone. Whether the gas cools efficiently, whether it burns, and what it does to the atmosphere in any other respect are all questions answered somewhere else.

The Environmental Protection Agency in the United States publishes reference points across the range, and they show how uneven the scale is. Halons reach as high as 10. The whole hydrochlorofluorocarbon family sits below 0.2. Hydrofluorocarbons sit at zero, and the agency gives the reason in one clause: they contain no chlorine.

The score follows one element through the atmosphere. EPA describes ozone depleting substances as compounds that release chlorine or bromine atoms once they break down high above the ground, and those loose atoms are what take ozone apart. How much of either element arrives up there, and how long it survives, is what a figure on this scale summarises.

Bromine does the same job harder, which is why the worst entries in the treaty are not cooling gases. Halons were built around bromine for fire suppression, and their scores sit above the reference compound. A refrigerant has never held the top of this scale.

Family names carry the answer before any table is opened. A chlorofluorocarbon holds chlorine and fluorine and little that helps it break apart early. Add hydrogen and the molecule becomes vulnerable in the lower atmosphere, so a smaller share of its chlorine survives the climb. EPA groups that whole hydrogen-bearing family below 0.2.

Take the chlorine out entirely and the score falls to zero. No engineering produced that result. It came from a change of composition, and it was finished across the industry well before most equipment now hanging on a wall was designed.

Treat ozone-friendly as a property of the chemistry when a brand attaches it to a product. Every manufacturer buying the same refrigerant inherits the same zero, at the same moment, without doing anything to earn it. A claim that cannot separate two boxes on a shop floor is decoration on a spec sheet.

The Montreal Protocol never counts raw kilograms. Article 3 sets out how a country's controlled level is worked out, and it instructs that annual production of each controlled substance be multiplied by the ozone depleting potential specified for it in the annexes. The ledger is therefore denominated in the measure itself.

Weighting the ledger set an exchange rate between substances. A low-scoring compound spent a small share of the allowance for the same tonnage, and anything above the anchor spent more than its weight. That arithmetic is how the hydrogen-bearing family got its opening, and EPA describes those compounds as transitional substitutes for the class above them.

The annexes are where a measure becomes a list. Each controlled substance appears in a group with its score attached, and that score travels with it into every national register built on the treaty. NEA runs the local register for the hydrochlorofluorocarbon family, licensing the companies that bring it across the border, and publishes a table of common HCFCs alongside their odp value.

How the tightening eventually reached one specific refrigerant is a longer story, and the r22 phase-out carries it. The part that belongs here is smaller. This measure never reached an owner. It reached production, it reached imports, and it reached the annex a substance was written into.

The gases in household splits sold here are hydrofluorocarbons, and that family carries no chlorine. EPA puts it in a single sentence: these substances have zero ODP because they do not contain chlorine. R32 and R410A both belong to the family, so both score zero, and so does anything else assembled from the same chemistry.

On this scale the current generation is flat. Two models on the same shop floor score identically, and they would have scored identically the day either was launched. A figure that stopped varying has no power to separate them.

A second index took over the question, and it grades a different harm. Ozone depletion asks what a substance does to the layer overhead. Global warming potential asks what it does to the heat balance below, and the current generation is being reduced under that second measure through the hfc phase-down.

So a refrigerant can be genuinely harmless to ozone while sitting under active restriction. Both statements hold at once. A sales conversation that mentions only the first has told you about the settled half and stopped short of the live one.

Keep the energy instruments clear of all this. Minimum energy performance standards sit on the electricity side of the machine, and the energy label reports what a buyer is entitled to see. Neither one reads the refrigerant.

The designations turning up in newer equipment overseas, R290 and R454B among them, hold no chlorine either. Nothing in the next transition is being driven by this measure, and no future gas will be chosen because of it.

Read it as a settled constraint and move to what still varies. Every household split lawfully on sale here holds a chlorine-free gas, so an ozone line in a brochure describes a condition the whole shop floor met before opening. What differs between two compliant models shows up elsewhere: in what the label reports about electricity, in the sizing, and in the workmanship at the wall.

An older system is a different conversation, and it was never a legal one. The phase-out reached production and import. Equipment already fitted kept running, and the charge sealed inside was never something an owner had to hand over. What genuinely shifted for those systems is how easily a refill can be bought, and r22 refrigerant has its own page for that.

Push back if ozone is offered as a reason to replace a machine that still cools. The measure placed no duty on any owner, and it stopped distinguishing between products years ago. Anybody reaching for it now is reaching for a word with warm associations and no remaining content.

Ask which refrigerant the system holds, then confirm it yourself. One look at the aircon rating plate ends the guessing, and the charge weight is printed beside it. Everything about the gas on either index follows from that one short string of characters.

• •Treat a zero on this scale as background. It stopped separating one product from another when the previous generation left production.
• •Ask for the designation printed on the plate. A refrigerant name can be checked against a published table. An adjective cannot.
• •Hold the two indices apart. One grades ozone damage and is closed out, the other grades warming and is still being tightened.
• •Refuse the replacement pitch when ozone is the reason offered. That word has no bearing on a machine already hanging on a wall.
• •Spend the attention on sizing and workmanship. Those still vary between two quotes. The ozone score does not.