Higg Assessment Model Release Artifacts
A HAM (Higg Assessment Model) release contains the compiled model, the schema describing its shape, and the guidance docs that explain how to consume it.
Start with guidance-ham.md for the overall framing — what HAM is, what’s in the bundle, how versioning works, and the terminology used across these docs.
Which doc do I want?
I’m wiring an application against a HAM server. Read
guidance-api.md. Covers the HTTP API surface, request/response shapes, version selection, and the refresh contract that lets the server pick up new releases without a restart.I’m embedding HAM evaluation in my own runtime. Read
usage.md. Covers the bundle file format, theschemaandblocksstructure, how to query withjq, and the high-level steps for implementing a record evaluator.I’m an analyst trying to understand the numbers that come out of HAM. Read the methodology guides:
guidance-ghgp-fem.md— GHGP-compliant FEM energy and emissions calculations.guidance-ghgp-alignment.md— how the FEM data aligns with the GHG Protocol scope 1/2 inventory guidance: assumptions, caveats, and the gaps a data consumer must fill. Read this before building an inventory from the records.guidance-eeci.md— Effective Energy Carbon Intensity metric.guidance-fep.md— Foundational Environmental Performance overlay.
I want to know the exact shape of a particular record type. Read
schema.md(human-readable schema dump). The machine-parseable form isschema.json.
Files in a release
| File | Purpose | Audience |
|---|---|---|
READ_ME_FIRST.md |
This index. | All readers. |
guidance-ham.md |
What HAM is, what’s in the bundle, versioning, glossary. | All readers. Start here. |
model.cbor.gz |
Primary artifact. CBOR-serialized Artifact struct, gzipped. |
Programmatic consumers (Rust, typed deserialisation). |
model.json.gz |
The same content as model.cbor.gz, expressed as JSON. |
jq, Python, JS-embedded evaluators. |
schema.json |
The bundle’s JSON schema. | Validators, code generators. |
schema.md |
Human-readable schema dump. | Analysts and developers exploring the data shape. |
usage.md |
Bundle-embedded evaluator implementation guide. | Integrators embedding HAM in-process. |
guidance-api.md |
HTTP API integrator guide for stl-local-server. |
Integrators consuming HAM via the API. |
guidance-ghgp-fem.md |
GHGP methodology for FEM energy and emissions. | Analysts and data consumers. |
guidance-ghgp-alignment.md |
Alignment of FEM data with GHGP scope 1/2 inventory guidance — assumptions, caveats, gaps. | Analysts and data consumers building inventories. |
guidance-eeci.md |
EECI methodology. | Analysts and data consumers. |
guidance-fep.md |
FEP methodology. | Analysts and data consumers. |
Documents
Higg Assessment Model
The Higg Assessment Model (HAM) is the compiled, evaluator-ready form of the Higg Index calculation logic. A HAM release is a single, versioned bundle: a JSON schema describing every record type, a compressed CBOR payload of the compiled block tree, and a…
Evaluating Assessments via the HAM HTTP API
This document explains how to call the stl-local-server HTTP API to evaluate a Higg assessment against a pinned HAM version. The audience is integrators wiring an application or service against a hosted HAM evaluator rather than embedding HAM into their…
Using the `model.json.gz` file
This document explains the structure of the model.json.gz file included in every HAM release and how to use jq to query it.
Higg Assessments Model Schema Reference
Every record type and field the model publishes.
GHGP Protocol Compliant FEM Calculations
This document provides guidance on the Greenhouse Gas Protocol (GHGP) compliant FEM calculations. The calculations are used to generate the data available in the Assessment, FacilityType, ReportedEnergyUse, EnergyUse, and Emissions records.
GHGP Scope 1 & 2 Alignment Guide
This document maps the FEM energy and emissions data — the Assessment, FacilityType, ReportedEnergyUse, EnergyUse, and Emissions records — against the GHG Protocol's scope 1 and scope 2 inventory guidance. It is written for data consumers (brands,…
Effective Energy Carbon Intensity (EECI)
This document explains the Effective Energy Carbon Intensity (EECI) metric as it appears in the Higg Assessment Model — what it measures, how it's calculated, where it lives in the schema, and what modelling assumptions and caveats apply when consuming it.
Foundational Environmental Performance (FEP)
This document explains how Foundational Environmental Performance (FEP) is represented in the Higg Assessment Model — what it measures, how the achievement aggregates are calculated, and what to read into the four FEP fields exposed on the Assessment record.
Published 11 September 2026.