The arrival of version 4.0 of the CO2 Performance Ladder also has implications for using the Ladder as an award criterion in tenders, although the changes are very limited. In this blog, we explain what the transition from version 3.1 to 4.0 means for procurement and when tenders with version 3.1 will definitively become a thing of the past.

To get straight to the point: little will change for contracting authorities with the transition from version 3.1 to 4.0. The main difference is in the change from five Levels to three Steps. To best support contracting authorities in using version 4.0 as a procurement tool, the new version of the Procurement Guide will be published in September this year.

CO2 Performance Ladder as BPQR award criterion

This means that the number of distinct levels when using the award criterion CO2 Performance Ladder on the basis of Best Price-Quality Ratio (BPQR) changes. Whereas in version 3.1 of the Ladder you define five different advantages (whether notional discounts on the tender price or points) for the five CO2 ambition levels, in version 4.0 there are only three. The percentage, fixed amount or number of points you choose as an award advantage is up to you. For example, you can give 5 points or 5% discount to step 1, 10 to step 2 and 15 to step 3.

CO2-ambition levelFictitious discount percentageFictitious discount amountPoints
Step 315%€150,000150
Step 210%€100,000100
Step 15%€50,00050

“Tenders are a wonderful and powerful tool to promote sustainability and work towards CO2 reduction”
Thijs Wentink, Sustainable Procurement project manager at SKAO

Project statement or Ladder certificate

Parties can – as in the previous version of the Ladder – demonstrate compliance with the set CO2 ambition level in two ways: via a project statement or via a CO2 Performance Ladder certificate. For both options, a party must demonstrate within an agreed deadline that it meets the requirements of the set CO2 ambition level. As the contracting authority, you determine this deadline and lay it down in advance. It is often one year.

In the blog ‘Tendering with the CO2 Performance Ladder: in line with EU procurement law’ you can read more about the two options, what to do if a tendering party does not comply and how to ensure that your use of the Ladder is in line with the European procurement directives. For example, you may not exclude parties that are not yet certified or do not want to be certified from a tender.

‘For contracting authorities, the Ladder is a relatively simple tool to deploy’
Vincent Swinkels, independent sustainability consultant VSSS

More room for monitoring and dialogue

Another change is that in version 4.0, there is more room for project monitoring and dialogue in tenders. Via the dashboard ‘My CO2 Performance Ladder’, the executing party keeps track of, among other things, how many CO2 emissions and the reduction measures realised during the execution of a project. This makes visible what is happening on the project and is a useful basis for dialogue between client and contractor. For example, discussing additional sustainability measures that could be taken, allowing the insights to be used for possible improvements in follow-up projects.

‘What we like about version 4.0 is that it provides more tools for client and contractor to enter into dialogue’
Gabriël Meijer, procurement officer at the municipality of Amsterdam

Transitional arrangement version 3.1 to version 4.0

SKAO advises contracting authorities to use the award criterion CO2 Performance Ladder version 3.1 for tenders in most cases until 14 January 2027. Deployment of version 4.0 before 2027 is only recommended if the contracting authority is convinced that the (international) market in which the tender is being launched is ready for it. This means that most parties that can submit a bid have a 4.0 certificate or will have one in the near future.

In all cases, SKAO advises against using award criterion CO2 Performance Ladder version 4.0 earlier than 14 January 2026, as there are very few companies that will already hold a Ladder certificate version 4.0 in 2025. Moreover, if a contracting authority plans to tender using the Ladder before 14 January 2027, we recommend informing the market about it.

Compatibility: using 4.0 certificates in 3.1 tenders

A contracting authority tendering with award criterion CO2 Performance Ladder version 3.1 may already receive a 4.0 certificate as evidence from tendering parties. SKAO recommends accepting these certificates as evidence. You then equate Step 1 with Level 3 (3.1) and Step 2 or 3 with Level 5 (3.1). At the same time, we advise against accepting 3.1 certificates for 4.0 tenders.

From January 2027, tendering with version 3.1 of the award criterion CO2 Performance Ladder will no longer be possible. Read more about the transition scheme from version 3.1 to version 4.0 here.

Explanation video about procurement with version 4.0

In the (dutch) video below (with English subtitles), Thijs Wentink, Vincent Swinkels and Gabriël Meijer elaborate on procurement with the CO2 Performance Ladder version 4.0. In the video, they also answer questions from organisations that attended the session. The main questions asked are addressed in the FAQ below. Should you still have questions after watching the video, please contact us.

This video is a recording of the webinar given on 6 March 2025.

Are certifying bodies accredited for version 4.0 from the start?

We know that all certifying bodies are currently working hard to extend their 3.1 accreditation to version 4.0. We expect that most of them will be ready by around 14 July, but we cannot guarantee that they will all meet this deadline.

Can a sustainability report drawn up for the CSRD and approved by the auditor be used as alternative evidence in procurement procedures?

As long as the CSRD report addresses climate mitigation, it can be an important part of the reporting needed to obtain a CO₂ Performance Ladder certificate. However, a CSRD report cannot be a full alternative to the certificate. This is because the Ladder, as an energy and CO₂ management system, goes much further in terms of scope, depth and ambition. In this respect, the CSRD is ‘merely’ a reporting tool. More information on the relationship between the CSRD and the Ladder.

Does using the CO₂ Performance Ladder comply with European procurement legislation?

Yes, using CO₂ Performance Ladder 4.0 as an award criterion for the best price-quality ratio (BPQR) is in line with European legislation, provided you apply it in the way prescribed by SKAO. Read this article for a detailed explanation.

How do I know whether an organisation actually achieves the CO₂ ambition level it tendered with?

Organisations that tender in a procedure using the CO₂ Performance Ladder BPQR criterion can meet this requirement in two ways. In both cases, the organisation must demonstrate within one year of the award – and annually thereafter for the duration of the project – that it meets the BPQR criterion CO₂ Performance Ladder:

  • By submitting a CO₂ Performance Ladder certificate at the proposed CO₂ ambition level. This demonstrates that the tenderer meets the requirements of the Ladder, including for CO₂ Performance Ladder projects.
  • By project-specifically meeting the requirements of the CO₂ Performance Ladder award criterion at the proposed ambition level, and submitting a project statement.

In both cases, the assessment of the CO₂ ambition level is the responsibility of an external and independent party: a Certifying Body accredited for the CO₂ Performance Ladder. The contracting authority does not need to verify compliance itself, but only to receive a project statement or certificate approved by the Certifying Body.

How do I know whether the awarded organisation is taking measures on my project?

If an organisation demonstrates through a CO₂ Performance Ladder certificate that it meets the requirements of the agreed CO₂ ambition level, it has an operational CO₂ management system. This is audited annually by an independent Certifying Body (CB). During the audit, the CB reviews not only the objectives and measures at the organisational level, but also takes samples from the projects with a CO₂ Performance Ladder procurement advantage that the organisation is carrying out.

If an organisation demonstrates project-specifically that it meets the CO₂ Performance Ladder award criterion, it must take reduction measures on the project. The CB verifies whether these measures are actually being implemented and whether the requirements of the agreed CO₂ ambition level are being met. The CB then draws up a project statement.

How do I use the CO₂ Performance Ladder in a procurement procedure?

The CO₂ Performance Ladder as a procurement tool consists of the CO₂ Performance Ladder BPQR criterion, which can form the basis for awarding a procurement advantage. When using the CO₂ Performance Ladder BPQR award criterion, you can, for example, choose to reward bidders with a fictitious discount or points based on their CO₂ ambition level. This criterion and the level of reward must be included in the procurement documents. By using the Ladder in a tender, you award the contract not to the lowest bidder, but to the one offering the best price-quality ratio (BPQR). The Procurement Guide 3.1 describes how the CO₂ Performance Ladder can be used as an award criterion. This guide also contains the wording of the CO₂ Performance Ladder 3.1 award criterion.

Read more on the Procurement page.

Is it possible to award a procurement advantage for step 3 from 2026 onwards?

The advice to contracting authorities is to only tender using version 4.0 in 2026 if they are confident that their market is ready for it. Once that is the case, we see no objection to rewarding step 3 as well. Whether this will happen in practice depends on the contracting authority in question.

Is it true that Level 3 is equivalent to Step 1, Level 5 to Step 2, and that Step 3 represents a higher level of ambition?

‘Equivalent’ is not entirely the correct term. We assume that organisations on Step 1 must make at least the same effort as organisations certified at Level 3. The same applies to organisations certified at Step 2 compared to those certified at Level 5. Step 3 does indeed require substantially more effort than Level 5. As a result, our advice to contracting authorities is to value Step 1 at least equally to Level 3, and Steps 2 and 3 at least equally to Level 5. This is explained in the transition arrangement 3.1–4.0.

May I use the CO₂ Performance Ladder as a suitability requirement or selection criterion?

The CO₂ Performance Ladder is not suitable as a suitability requirement or selection criterion. There are several reasons for this:

  • Implementing the CO₂ Performance Ladder within an organisation takes time and effort. In most cases, it would be disproportionate to require that an entire organisation be certified before being allowed to tender for a specific project. This would be unreasonable for a project that represents only a (small) part of the organisation’s turnover. From a procurement law perspective, there would be insufficient link between the requirement and the subject of the contract. For this reason too, such a requirement is not permitted as a suitability or selection criterion.
  • Using a certificate as a suitability requirement or selection criterion would mean that parties without the required (level of) certificate cannot participate or are less likely to be selected. This would be discriminatory, for example, to foreign parties or small businesses. From a procurement law perspective, this is not allowed.

This principle applies to all tenders: European, national and negotiated procedures. Even for small contracts, such a suitability requirement is still discriminatory.

Must an organisation be certified in order to participate in a tender that uses the CO₂ Performance Ladder?

No, this is not necessary. Organisations that submit a tender in which the CO₂ Performance Ladder is used as an award criterion, do so with a CO₂ ambition level at which they intend to carry out the contract. After the award, the organisation must demonstrate within one year that it meets the requirements of the CO₂ Performance Ladder award criterion, either by submitting a CO₂ Performance Ladder certificate or a project statement for the proposed CO₂ ambition level.

What communication obligations apply to contractors at the start and end of projects?

There must be a communication plan for CO₂ Performance Ladder projects that is tailored specifically to the project. The content of communication is therefore customised. However, CO₂ Performance Ladder 4.0 does set some minimum requirements. For instance, there must be regular internal project meetings and meetings with project partners (including subcontractors) and the client. Both internal and external meetings must address:

  • the selection and progress of the implementation of measures;
  • the progress and trends in energy consumption on the project;
  • the progress and trends in emissions resulting from energy consumption on the project;
  • the progress and trends in upstream and downstream emissions on the project.

What happens if a company fails to achieve the agreed CO₂ ambition level?

It may happen that the contractor is unable to meet the requirements of the CO₂ Performance Ladder award criterion through a project statement or certificate, either fully or on time. In this case, the contracting authority must include a sanction in the procurement documents.

The recommendation is to include a sanction that exceeds the awarded procurement advantage. To determine the amount of the sanction, calculate the difference between the quality value awarded in the procurement procedure – the agreed CO₂ ambition level – and the final quality value achieved (CO₂ ambition level), and multiply this by a factor (e.g. 1.5). A sample sanction clause is included in Annex A of the Procurement Guide 3.1.

Example: CO₂ ambition level 3 resulted in a quality value of €50,000 at the time of tendering but was not achieved by the contractor. The contractor submits a CO₂ Performance Ladder Certificate at level 2, associated with a quality value of €30,000. The sanction amount will then be 1.5 x (€50,000 – €30,000) = €30,000.

What happens to existing certificates during the transition from version 3.1 to 4.0? Are they still valid?

Existing 3.1 certificates remain valid until the first audit date after 14 January 2027. From 14 January 2027 onwards, no 3.1 audits may take place, so the organisation will automatically switch to version 4.0 and the 3.1 certificate will expire. In theory, this means that the certificate may still be valid until 14 January 2028.

What is the added value of a CO₂ Performance Ladder certificate compared to a project statement?

A CO₂ Performance Ladder certificate is much more cost-effective (in terms of time and money) for organisations that tender for multiple projects or contracts using the CO₂ Performance Ladder. The certificate demonstrates that the entire organisation operates in a CO₂-conscious way, including the CO₂ Performance Ladder projects it carries out. A major advantage is that the certificate can be used in all tenders (also from different contracting authorities) that use the CO₂ Performance Ladder award criterion. A project statement is valid only once, specifically for the project for which it is issued by a Certifying Body.

What procurement advantage should I give per CO₂ Performance Ladder level?

Each CO₂ ambition level should come with a procurement advantage. As the contracting authority, you determine the procurement advantage per level. Most contracting authorities work with percentages, but fixed amounts or points are also possible.

The value of the procurement advantage and the method used to calculate it must be specified in the contracting authority’s procurement documents, so that it is clear how this advantage relates to the valuation of other qualitative elements (BPQR criteria) of the tender. See the Procurement Guide 3.1 and, from September, the Procurement Guide 4.0.

When will the 4.0 procurement guide be published?

The CO₂ Performance Ladder 4.0 award criterion – part of the CO₂ Performance Ladder Handbook version 4.0 – will be published in September 2025 in the Procurement Guide.

Which contracting authorities use the Ladder in procurement procedures?

There are more than 8,000 organisations with a CO₂ Performance Ladder certificate, and over 300 contracting authorities in the Netherlands and, among others, in Belgium, Ireland, France, the UK, Germany and Portugal use the CO₂ Performance Ladder in procurement. These include national government bodies, municipalities, water authorities and provinces. For an overview of these contracting authorities, see the Participants page.