Under the AIM Act rule (40 CFR §84.106), you calculate a leak rate every time refrigerant is added to a covered appliance. There are two EPA methods, they can disagree on the same event, and the result decides whether a 30-day repair clock starts. Here's exactly how each one works — with a worked example where they land on opposite sides of the line. Prefer to just get the number? Use the free calculator →
A leak-rate calculation is required on every addition of refrigerant to an appliance with a full charge of 15+ lbs of a regulated refrigerant. §84.106(b) "Full charge" is the amount the appliance holds in normal operation, per the manufacturer, calculation, measurement, or an established range. You must choose one method per appliance and apply it consistently — you can't cherry-pick whichever gives the lower number that day.
The annualizing method takes a single addition and extrapolates it across a full year:
It answers: "if the appliance kept leaking at the rate implied by this top-off, how much would it lose in a year?" Because it annualizes a recent event, a big addition after a short interval produces a high number fast.
The rolling-average (12-month) method sums the actual leak-related additions over the trailing 365 days:
It answers: "how much did this appliance actually lose over the last year?" It smooths out a single large top-off but reflects a full year of history.
Take a 100-lb commercial rack. A tech adds 12 lbs today, 90 days after the last service.
| Method | Calculation | Result | vs 20% commercial threshold |
|---|---|---|---|
| Annualizing | (12 ÷ 100) × (365 ÷ 90) × 100 | 48.67% | Over — repair clock starts |
| Rolling average | Say the year's additions total 17 lbs: (17 ÷ 100) × 100 | 17.0% | Under — no trigger |
Same appliance, same period — one method triggers a 30-day repair obligation and the other doesn't. That's not a loophole; it's why the EPA makes you pick a method and stick with it. Choosing wrong (or switching) is exactly the kind of thing an auditor flags.
The free calculator runs both methods side by side → so you can see the difference on your own numbers, with the CFR citation on each.
Exceed the threshold for the appliance's category and the 30-day repair clock starts. §84.106(c)(2)
| Appliance type | Leak-rate trigger |
|---|---|
| Industrial process refrigeration | 30% |
| Commercial refrigeration | 20% |
| Comfort cooling | 10% |
| Refrigerated transport | 10% |
| Other | 10% |
See the leak-repair requirements guide for what happens once the clock starts, and the 15-lb rule overview for who's covered.
from $19/mo. Automatic leak-rate calculation in either EPA method, threshold check, 30-day clock, and the audit binder.
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