How a GreenTurtle figure is made.
The Standard is a self-assessment framework. It is not an audit and not a third-party certification, and it never claims to be.
What is in scope
Cars, vans and HGVs you operate, plus grey-fleet mileage claims and business travel by rail, air and road.
- Vehicles you operate, whether owned, leased or hired
- Grey fleet claimed as mileage
- Business travel: rail, air, taxi, hotel nights
Distance
One of three sources per vehicle, tagged on the row and counted on the certificate.
- contracted — from the lease or hire agreement
- odometer — from a dated reading or telematics
- default — 8,000 miles, amber, always named
Powertrain
How each vehicle's emissions per kilometre are derived.
- Battery electric — DESNZ per-km grid factor
- Plug-in hybrid — DESNZ PHEV per-km factor
- ICE — WLTP figure × 1.15 real-world uplift
- Unknown — desnz_avg_car / desnz_avg_van fallback
Factors
We publish the factor set and the year it came from. Factors are never back-applied to a closed period.
- DESNZ conversion factors, stated by year
- Factor changes reported apart from operational change
- The factor table is public
Tiers
Bronze under 20% battery electric, Silver from 20%, Gold from 40%, Platinum from 60% of fleet distance.
- Always displayed with 'self-assessed'
- Never 'Certified' or 'GreenTurtles-approved'
- Recalculated at each issue, not carried over
Certificates
Each certificate gets a code and a public record at greenturtles.co.uk/verify.
- Codes in the form GT-XXXX-XXXX
- The verify link appears wherever the mark appears
- Revocations stay public
Provenance, on every row
Every vehicle in your assessment carries the tag that says where its distance came from. Contracted mileage is green. An odometer reading is green. A default is amber, named, and counted in the defaults figure on your certificate.