# GreenTurtle Standard — v1

**Brand:** GreenTurtles (greenturtles.co.uk) · **Status:** v1, published 4 September 2026 · **Engine:** `pub/app/carbon.js`
(unit-tested, single source of truth) · **Verify pages:** `/verify/<code>`

The standard exists to make one promise credible: **every figure FleetGenius
shows about a fleet's carbon can be traced to how it was made.** It is a
self-assessment framework — not an audit, not a third-party certification, and
it never claims to be. That honesty is deliberate: it is what lets the
certificate carry a public verification link instead of a logo.

## 1. What is measured

Annual CO₂e for every unarchived vehicle on the tenant's register, using the
**GHG Protocol distance-based method**: distance travelled × an emission factor
per kilometre.

- **Distance** — recorded contracted annual mileage; else lifetime odometer ÷
  vehicle age; else a named default of 8,000 miles. The source is carried on
  every figure (`contracted` / `odometer` / `default`) — a default is never
  silent.
- **Factor** — chosen per powertrain (§2), from the UK Government's (DESNZ)
  2026 conversion factors for company reporting.

## 2. Powertrain treatment — the honest choices

| Powertrain | Factor | Why |
|---|---|---|
| Battery electric | DESNZ average BEV per-km (scope 2) | **An EV is not zero.** The grid electricity it charges from is counted and labelled. |
| Plug-in hybrid | DESNZ average PHEV per-km | WLTP figures for PHEVs (26–50 g/km) assume daily charging and understate real-world use ~3–4×; they are never used for totals. |
| Petrol / diesel / HEV with a type-approval figure | vehicle's WLTP g/km × **1.15 real-world uplift** | Type-approval understates on-road CO₂ by ~15–20% (EEA on-board fuel-consumption monitoring). |
| No recorded g/km | DESNZ average for the fuel and body (car/van) | Named as `desnz_avg_*` in the method field. |

## 3. Factors and provenance

Factors live in `FACTORS` in `pub/app/carbon.js` with dataset name, seed date,
sources and a `verified` flag. **Current state: seeded 4 Sep 2026 from a
secondary aggregation of the DESNZ 2026 workbook; `verified:false` until each
value is checked against the official spreadsheet**
([gov.uk collection](https://www.gov.uk/government/collections/government-conversion-factors-for-company-reporting)).
Changing a factor is a one-line PR that shows in the git history.

## 4. History and trend claims

A scheduled job (`carbon-snapshot.mjs`, 1st of each month) stores one row per
tenant per month. **A year-on-year claim is only ever shown when a snapshot
~12 months old exists to compute it from.** Until then the UI says the baseline
is building. (v1 of this screen displayed a synthesised reduction figure; that
was removed on 4 Sep 2026 and must not return.)

## 5. Tiers

Share of the fleet that is pure battery electric: **Bronze** <20% ·
**Silver** ≥20% · **Gold** ≥40% · **Platinum** ≥60%. These are GreenTurtles'
own published thresholds, self-assessed — the words "verified" or "certified
by" never appear against a tier.

## 6. Certificates and verification

Issuing a certificate writes a read-only summary (tier, annual tonnes, fleet
size, zero-tailpipe count, electrified %, period, method version) under a code
`GT-XXXX-XXXX`, publicly served at `greenturtles.co.uk/verify/<code>` (fleetgenius.co.uk serves the same route) with the
method and the self-assessed status stated in plain sight. Certificates can be
revoked (god/crm), and a revoked certificate says so on its verify page.
Nothing else about the fleet is exposed.

## 7. Known limits (stated, not hidden)

- Distance-based estimation, not measured fuel/energy — suitable for
  management, engagement and directional reporting; an SECR disclosure should
  use actual fuel/energy where available.
- Grey fleet, WTT (well-to-tank) and vehicle embodied carbon are out of scope
  in v1.
- Mileage quality varies; provenance chips mark estimates until DVSA/telematics
  confirm.

## Brand

The standard is published under **GreenTurtles** (Bluepoppy's green-mobility
brand, greenturtles.co.uk); the measurement engine and data live in FleetGenius.
Certificates and verify pages read "GreenTurtle Standard v1 · powered by
FleetGenius". Van stickers and any advertising must anchor the claim: tier +
verify code/QR + year — never an unanchored "greener future" line
(CMA Green Claims Code). Architecture and roadmap: docs/GREENTURTLES-BRAND.md.

## Revision log

- **v1 (GreenTurtles) — 4 Sep 2026.** Rebranded from the working title "Fleet
  for Good" to the GreenTurtle Standard; codes GT-XXXX-XXXX; verify host
  greenturtles.co.uk. Method unchanged.
- **v1 — 4 Sep 2026.** First published version. Replaced the WLTP-only
  quarterly estimate and removed unverifiable claims ("verified against GHG
  Protocol / ISO 14083 / SECR", fabricated year-on-year reduction, "Certified"
  wording) from the screen, certificate and report.