CO₂ Performance Ladder checklist: evidence per version and rung
Choose the version of the handbook first, then use the right checklist. During the transition period, handbook 3.1 with five levels and handbook 4.0 with three rungs exist side by side. The official SKAO transition scheme explains how long both routes remain available. Use the levels and rungs page for terminology and the audit process page for the assessment.
Handbook 4.0 was published on 14 January 2025. Audits under 4.0 have been possible since 14 July 2025. New 3.1 audits can take place under the transition scheme until 14 January 2027. Existing 3.1 certificates may remain valid until 14 January 2028 at the latest, depending on the next annual audit. Record the version, rung or level and the reference date at the top of your evidence register.
Checklist for handbook 4.0
The four themes of insight, reduction, transparency and participation are still recognisable. Do not present them as four new requirements that only arrived with 4.0. Version 4.0 changes the structure to rungs and adds substantive emphasis, such as a climate transition plan and more attention to the value chain at higher rungs.
| Theme | Evidence you record | Owner | Status and review date |
|---|---|---|---|
| Insight | Organisational boundary, energy data, emission factors, footprint period | Energy manager | Draft / date |
| Reduction | Targets, measures, progress and deviations | Management | Open / date |
| Transparency | Internal and external communication with version control | Communications | Done / date |
| Participation | Sector or chain initiative, contribution and evaluation | Project manager | Open / date |
| Value chain | Chain analysis and relevant scope 3 information where 4.0 requires it | Procurement | Open / date |
| Transition | Climate transition plan with actions, resources and deadlines | Management | Open / date |
Link each item to a file name, a person responsible and the last check. Keep source data next to the calculation: invoices, meter readings, fuel records and the emission factors used. Record changes so that an auditor can reconstruct why a figure changed.
Footprint check before the audit
Work through these questions:
- Is the organisational boundary the same as the scope of the certificate?
- Are all relevant energy sources and locations included?
- Is the source and version of each emission factor recorded?
- Are the period, conversions and rounding reproducible?
- Has someone checked the calculation independently?
- Is it clear which scope 1, scope 2 and any scope 3 emissions are included?
A contractor with diesel vans, a workshop and hired-in transport does not keep only the total chart. It records fuel cards, energy invoices, the method for hired-in transport and a check by a second person.
If you still work to 3.1
Then use the requirements and level names of 3.1 consistently. Do not mix “level 3” with “rung 1” from 4.0 without explanation. The transition mapping is not a one-to-one conversion: rung 1 roughly corresponds to old levels 1 to 3, but is substantively stricter than old level 3. When you switch, discuss which documents need to be assessed again.
An existing 3.1 register can remain useful as a source, but check the new structure, value chain and transition requirements against the chosen 4.0 document. For tenders, the transition scheme provides a limited acceptance mapping: 4.0 rung 1 counts as 3.1 level 3, and 4.0 rung 2 or 3 counts as 3.1 level 5. This is not a substantive one-to-one equivalence. The official handbook 4.0 downloads are the starting point. Choose the download that matches your rung.
Fictional case: SME contractor
A contractor with one workshop chooses 4.0 rung 1. The footprint covers gas, electricity and diesel. The checklist flags three gaps: the emission factor for diesel is not recorded, management has no reduction target with a deadline, and external communication has no review date. The owner fills in the three points, has the calculation checked and stores the evidence in an audit folder.
The register then shows exactly who did what. It does not promise any award advantage: the contracting authority decides the notional discount or points and the conditions itself.
A checklist is an evidence register, not a certificate. The certification body assesses the chosen version, rung, scope and how your system works.
Frequently asked questions
Do I have to move to handbook 4.0 straight away?
That depends on your certificate, contracts and tenders. Discuss the transition with your certification body and check the SKAO scheme.
Is “level 3” the same as “rung 1”?
No. The versions use different structures and the content is not entirely the same. Always state both the version and the level or rung.
What award percentage will I get?
That is not fixed in the ladder. The contracting authority decides the advantage, the points awarded and the evidence conditions.