Can I use Annualizing for some systems and Rolling Average for others?

No. The EPA requires that you choose one calculation method and apply it consistently across your entire organization. You cannot switch methods per system, per event, or per refrigerant to produce a more favorable result.

Which EPA leak rate method produces lower results?

Neither method is inherently lower. Annualizing tends to produce higher rates when service events are close together, while Rolling Average tends to produce higher rates when many small additions accumulate over time. The better choice depends on your service patterns.

What happens on the first service event after January 1, 2026?

For the Annualizing method, the first event uses D = 365 (the maximum window), which means the rate is not amplified. For Rolling Average, the first event is the only one in the window, so the rate equals (lbs added ÷ full charge) × 100. Both methods are designed to avoid artificially high rates for the initial event.

Can I change my calculation method later?

Technically yes, but switching mid-year can create inconsistencies in your records. If you do switch, apply the new method going forward and document the change. For audit purposes, it's best to pick a method and commit to it.

Do both methods count the same service events?

Both methods only count refrigerant additions made on or after January 1, 2026. The difference is how they use the data: Annualizing looks at individual events in relation to the previous event, while Rolling Average looks at the cumulative total of all events within a 365-day window.

Annualizing vs Rolling Average Leak Rate — Which EPA Method to Use

The Annualizing Method

The Annualizing method projects a single refrigerant addition over a full 365-day period. It answers the question: "If this system kept leaking at this rate all year, what would the annual leak rate be?" The formula is: Leak Rate = (lbs added ÷ full charge) × (365 ÷ D) × 100, where D is the number of days since the previous refrigerant addition. For the first event after January 1, 2026 (or the first event ever for a newly tracked system), D defaults to 365 — meaning the first addition is not annualized upward. This prevents a single early addition from producing an artificially high leak rate.

Note

The annualization factor (365 ÷ D) amplifies small additions over short periods. Adding 2 lbs to a 50-lb system after 30 days produces a 48.7% leak rate — much higher than the 4% raw ratio suggests.

The Rolling Average Method

The Rolling Average method sums all refrigerant additions within the most recent 365-day window and compares the total to the system's full charge. The formula is: Leak Rate = (sum of all lbs added in last 365 days ÷ full charge) × 100. Only additions on or after January 1, 2026 are included. This method is cumulative — every addition in the window contributes to the rate, regardless of timing. The rolling window moves forward with each new service event, and older events naturally drop off as they fall outside the 365-day lookback.

When Annualizing produces higher results

The Annualizing method tends to produce higher leak rates when service events are close together in time. The shorter the interval between additions, the higher the annualization factor. For example, if you add refrigerant twice in a 2-week span, the second event will be annualized over just 14 days — amplifying the rate by a factor of 26. This makes Annualizing more sensitive to burst patterns and can trigger threshold exceedances faster than Rolling Average would for the same data. Systems that require frequent top-offs in a short period are more likely to show elevated rates under Annualizing.

When Rolling Average produces higher results

Rolling Average tends to produce higher rates when a system has accumulated many small additions spread throughout the year. Since every addition in the 365-day window counts, the cumulative total can exceed what any single annualized event would show. For systems with chronic, low-level leaks that get topped off monthly, the Rolling Average will steadily climb as additions accumulate — even if no single event looks alarming under Annualizing.

Which method should you choose?

The EPA requires you to choose one method and apply it consistently across your organization. You cannot switch methods per system or per event to cherry-pick the lower number. That said, here are practical guidelines. Annualizing is often better for systems serviced infrequently (once or twice a year), because it gives a meaningful snapshot from each individual event. Rolling Average is often better for systems serviced frequently (monthly or quarterly), because it smooths out individual variations and provides a more stable compliance picture. For most small HVAC contractors with a mix of residential and light commercial systems, Annualizing is the simpler choice — it requires no historical lookback, and each event produces an immediate result.

Pro Tip

Pick your method once and stick with it. Ref LeakLog lets you set your organization's calculation method in Settings and applies it automatically to every service event.

Practical example: same data, different results

Consider a 50-lb comfort cooling system (10% threshold) with two service events in 2026: 3 lbs added on March 15, and 2 lbs added on June 15 (92 days later). Under Annualizing, the March 15 event calculates as (3 ÷ 50) × (365 ÷ 365) × 100 = 6.0% (compliant). The June 15 event calculates as (2 ÷ 50) × (365 ÷ 92) × 100 = 15.9% (exceeds 10% threshold — repair required). Under Rolling Average, the June 15 calculation sums both events: (5 ÷ 50) × 100 = 10.0% (right at the threshold). Same system, same service history — but Annualizing triggers a repair action while Rolling Average shows the system at exactly the limit. This is why method selection matters.

Annualizing vs. Rolling Average: EPA Leak Rate Methods Explained

Key Takeaways