United States

EPA Waste Reduction Model (WARM) v16

A decision-support model for comparing what happens to the same waste under different pathways. Not an inventory source, and Slate keeps it separate.

WARM versions page About WARM Waste factors vs WARM (PDF)

materials in 11 categories

published pathway columns

pathways in Slate

512

values imported

Overview

WARM estimates the life-cycle greenhouse gas effect of managing a tonne of a material one way rather than another: landfilling, recycling, combusting, composting, digesting or not producing it in the first place. Its figures include avoided emissions, so recycling aluminium cans is a large negative number.

That makes WARM the right tool for the question "what if we changed how we handle this waste?" and the wrong one for "what did our waste emit?". Slate's Waste Data module uses it for baseline-versus-alternative scenarios and keeps it out of Scope 1, 2 and 3 totals entirely.

Slate imports EPA's own v16 workbook. It used to hold a hand-typed copy, which turned out to have sign errors: newspaper landfilled was +0.08 where EPA publishes −0.846139.

At a glance

Publisher: U.S. Environmental Protection Agency
Code in Slate: US_EPA_WARM
Covers: Waste management scenarios: 61 materials across disposal and recovery pathways
Publishing schedule: Irregular. v16 was published December 2023.
Licence: U.S. Government work (public domain)
Bulk download: Permitted by the licence, from the publisher

Official files

These go straight to the publisher, never to a copy hosted by Slate. Where a page holds several files, the note names the exact one Slate imports.

Data filewarm_v16.xls
Published Dec 2023. The workbook Slate imports, including its energy and economic summary sheets.
Get file
GuidanceEmission factors for waste vs WARM
Published Apr 2020.
Open

Releases in Slate

A release is one immutable published edition. Slate keeps the publisher's file unmodified, records its checksum, and selects a release by the date of each activity, so a 2022 record is always priced on 2022 data.

Release	Edition	Valid for	Values	Blank	CO₂e	GWP basis	Status
US EPA WARM v16	`warm`	Open-ended	512	285	Pre-calculated CO₂e	IPCC AR5 100yr	Scenario only

Blank counts are cells the publisher left empty. Slate stores them as missing, never as zero.

What Slate uses it for

Waste Data scenarios

Each analysis compares a baseline against an alternative across recycled, landfilled, combusted, composted, anaerobically digested and source-reduced tonnages.

Anaerobic digestion as WARM sets it

WARM publishes four digestion columns. Slate uses the one WARM's own blank workbook selects: dry digestion with curing. Wet digestion is marked not applicable for yard trimmings and four other materials, so a wet default would silently return zero for them.

Energy and economic figures

WARM's energy (MMBtu), labour, wage and tax figures are imported beside the emission values.

How Slate handles it

The decisions that change numbers, and why they were made the way they were.

01
Never added to an inventory
EPA says WARM results "shouldn't be presented as part of the organization's Scope 1, 2, and 3 inventories". WARM has no route into Slate's factor chain, and no organisation setting can select it.
02
Two answers to two questions
EPA's own example: recycling 100 short tons of aluminium cans is a net saving of 913 MTCO₂e in WARM (−9.127378 per short ton) and +6 MTCO₂e in a Scope 3 inventory (Hub Table 9, +0.06). Both are correct for their own question.
03
Units
WARM values are stored in kilograms like every other factor. A scenario total is reported in metric tonnes CO₂e. A missing division would be a thousandfold error that still looks plausible, so the conversion lives in one place.

Check a figure yourself

1
Download WARM v16 from EPA's versions page.
2
Open the summary emissions sheet and find the material and pathway.
3
The value matches Slate's per-short-ton figure to the sixth decimal place.

Where to find the reference

Every calculated record in Slate has a provenance panel showing the release, the publisher's own row reference and the GWP set applied. See Calculated Emissions & Errors.

Licence and attribution

Licence: U.S. Government work (public domain)
Attribution: Source: U.S. EPA, Waste Reduction Model (WARM) v16.