Sustainability · January 12, 2023
How We Calculate Avoided Carbon, Including the Weak Parts
If you're going to publish environmental numbers, you owe people the method — including the parts you'd attack first.
The short version
EPA WARM v16 factors applied to measured component masses, cradle-to-gate for the avoided new container, freight excluded from both sides. Roughly 152 lb CO₂e avoided per reused 275-gallon unit. Not independently audited, and we say so everywhere we use it.
Environmental claims are cheap. Arithmetic is not, and arithmetic you're willing to publish in full is rarer still. This is our method, the numbers it produces, and the three places where we'd start if we were trying to disprove our own figures.
The inputs
Component masses are measured across our own intake, not taken from a manufacturer's brochure. Anyone with a scale can check them.
| Component | Mass used | Basis | Confidence |
|---|---|---|---|
| HDPE bottle | 50 lb | Weighed sample across mixed manufacturers | High |
| Steel cage and frame | 43 lb | Weighed sample, galvanized tubular | High |
| Pallet base | 26 lb | Composite base — our most common configuration | Medium; the mix varies |
| Valve, lid, gaskets | 4 lb | Weighed sample | High |
The factors
US EPA WARM version 16 for HDPE and carbon steel manufacture, applied to those masses on a cradle-to-gate basis. WARM was chosen because it's public, widely accepted in North American materials reporting, and applies transparently to masses anyone can verify. A commissioned life-cycle assessment would be more precise and far less checkable.
| Metric | Per unit | Source |
|---|---|---|
| CO₂e | 152 lb | WARM factors × component masses |
| Virgin HDPE | 50 lb | Direct mass avoidance |
| Steel | 43 lb | Direct mass avoidance |
| Process water | 310 gal | Published intensity for virgin HDPE and primary steel |
| Energy | 96 kWh | Moulding, welding, galvanizing, assembly |
| Landfill volume | 63 cu ft | Uncompacted external volume — composite IBCs don't compact |
The boundary
Included: raw material extraction and processing for the avoided new container, polymer moulding, steel production and forming, welding, galvanizing, assembly, and process water for virgin materials.
Excluded: distribution freight, warehousing, the use phase, end-of-life, packaging waste at the manufacturer, and capital equipment.
Why freight is excluded
Because it appears on both sides. A new container also has to be manufactured, warehoused and trucked to you — usually from further away than our yard. Counting our freight while ignoring theirs would bias the comparison toward the answer we want, which is precisely the move that makes environmental claims worthless.
The three assumptions we'd attack
Every methodology has soft spots. Publishing ours is the difference between a method and a marketing page.
1. Linear scaling by capacity
Our calculator scales factors by capacity ratio across sizes. In reality, larger containers use proportionally less material per gallon, so we're understating the benefit for 330 and 350 gallon units. We've left the conservative version in place rather than modelling it.
2. Pallet mix
We apply a composite base mass to all units. Actual intake is a mix of composite, steel, plastic and a declining tail of wood, with steel bases substantially heavier. Depending on the real mix in a given quarter, the steel figure could move by several percent in either direction.
3. Water intensity
Process water figures for virgin polymer and primary steel vary widely by region and facility. Ours is a mid-range published value applied uniformly, and it carries the widest genuine uncertainty band of anything in the method.
Equivalences, and why we're careful
Miles-not-driven and showers-worth-of-water are useful for intuition and terrible for reporting. We show them in the calculator because they help people feel the scale, and we'd encourage anyone citing the figures to report the underlying pounds of CO₂e instead.
Use the method
Everything needed to run these figures on your own container fleet is on this page: component masses, factor sources, boundary conditions and the weak points. A method only one company can apply isn't much of a method.
And if a number looks wrong to you, tell us. Being corrected costs nothing; being wrong in public costs plenty.
Published January 12, 2023 · Updated February 9, 2026 · Filed under Sustainability
