Methodology
How the numbers on every ATMO Approved page are calculated and verified.
Every company in this directory shows two headline figures: tonnes of CO2-equivalent avoided this year, and tonnes of TFA avoided over the lifetime of the systems they installed. This page is the reference for what those figures mean, how we arrive at them, and what we deliberately exclude.
Independently verified — not self-declared.
ATMO Approved is granted by ATMOsphere, the independent authority on natural refrigerants since 2006. Companies apply, submit installed-system data, and pass an internal audit before a single tonne is published.
Who runs the audit
ATMOsphere is the policy and market-intelligence organisation that has tracked natural-refrigerant deployments worldwide for nearly two decades. The calculations on every page are produced by the same team that publishes the annual State of the Industry reports and runs the ATMO Conferences in Europe, North America, Asia, and Latin America.
What it takes to earn it
Since 2022, over 90 companies have applied; roughly 1 in 5 have been approved or re‑approved. Eligible applicants must operate verified installations on natural refrigerants (CO2, ammonia, hydrocarbons, or water), demonstrate a credible measurement chain, and document the systems they count toward the figures on this site.
What the headline tonnes mean — and why GWP 20 and GWP 100 give different answers.
Avoided CO2e is the difference between the emissions a fleet of natural-refrigerant systems is expected to produce and the emissions the same fleet would have produced on the conventional HFC alternative.
Global warming potential (GWP) converts every refrigerant to a CO2 equivalent so that very different molecules can be compared on one axis. The two time horizons published by the IPCC give materially different answers for the high-impact HFCs that dominate today’s installed base:
- GWP 20 measures warming over the next 20 years. It is the time horizon most relevant to short-term climate targets — keeping warming below the 1.5 °C threshold this decade.
- GWP 100 measures warming over 100 years. It is the conventional horizon for national inventories and the F-gas Regulation.
Every company page publishes both, side by side, with a toggle that swaps the headline figure and every dependent visual in unison. Neither is “more correct” — they answer different policy questions.
The lifetime figure that doesn’t care about climate horizons.
Trifluoroacetic acid (TFA) is the persistent breakdown product of the HFOs marketed as the “clean” replacement for HFCs. Once formed, it does not decompose on any human timescale.
Because TFA accumulates, the meaningful unit is not annual emissions but lifetime emissions: the total mass that would have entered the atmosphere over the full operating life of the systems each company installed in the cohort year. That is the figure published on every page.
TFA avoidance is binary in a way that CO2e is not. A natural-refrigerant system avoids 100 % of the TFA the equivalent HFO system would have produced — the molecule simply isn’t present in the supply chain. The number on the page is therefore the full counterfactual mass, not a percentage reduction.
Year-by-year, so progress can be audited.
Where data is available, every page also publishes the trajectory chart — a per-year breakdown of avoided emissions for as many cohort years as the company has reported. The single-year headline is what changed; the trajectory is whether progress is sustained.
Years before a company first applied are not back-cast. Trajectory points only exist where a company submitted data for that year and ATMOsphere verified it. A missing year is not a zero — it is a deliberate gap.
Stating the limits as plainly as the headline figures.
The numbers are deliberately scoped to direct refrigerant emissions and the systems each company has reported. A few consequences worth naming:
- No energy-use accounting. Indirect emissions from the electricity each system consumes are out of scope. Many natural-refrigerant systems are also more efficient than their HFC equivalents; that benefit is not in the headline.
- No supply-chain accounting. Manufacturing footprint, refrigerant production, and end-of-life handling are excluded. The figures are operational avoidance only.
- Only what the company reports. Each figure reflects the systems a company chose to include in its application. We verify what is submitted; we do not count installations a company does not report.
- Counterfactual, not measurement. Avoided emissions are computed against the most common HFC alternative for each application. Real-world leak rates and ambient conditions may move the absolute number; the relative ranking between companies is what the label certifies.
Questions about the methodology