In short
- The Ladder scores the organisation and the MKI scores the project. A single Rijkswaterstaat tender can ask for both.
- They score differently too: at Rijkswaterstaat the Ladder as a notional reduction of the bid sum, the MKI as a quality criterion where a lower value wins.
- Neither substitutes for the other, and the data behind them comes from different places: an organisational inventory versus a life cycle assessment of a design.
The CO2-Prestatieladder scores your company and the MKI scores your design. That is the whole difference, and it is why one bid can need both. The Ladder is a certification scheme measuring how your organisation manages its emissions, turned into an award advantage whose form the buying authority sets: Rijkswaterstaat deducts a notional percentage from the bid sum, while SKAO also describes a points weighting, and the tender documents say which applies. The MKI, the Milieu Kosten Indicator, is a single monetised number from a life cycle assessment of the specific thing you are proposing to build, weighed as a quality criterion where a lower number scores better. They answer different questions and satisfying one does nothing for the other.
What is each one measuring?
The Ladder measures a management system. An accredited certifying body audits your organisational greenhouse gas inventory and the goals, roles and plans around it, and you certify against a trede: trede 1 for your own operations, trede 2 for the value chain, trede 3 for a route to zero emissions by 2050 at the latest. The output is a certificate about a company.
The MKI measures a design. A life cycle assessment of the materials, products and processes in a proposed solution is converted into one euro figure by the shadow-price method. Rijkswaterstaat's own tool DuboCalc, developed by Rijkswaterstaat and maintained by Netcompany, is one of several validated calculators that produce it. The output is a number about a project.
The practical consequence: your Ladder trede is the same on every bid you submit this year. Your MKI value is different on every bid, because it belongs to the design.
One relief for a bid team under time pressure, because it is widely misunderstood: you do not have to hold the certificate when you bid. You declare the trede you are offering and prove it afterwards, and at Rijkswaterstaat you have up to a year after award to demonstrate it. What you cannot do is declare a trede you then fail to reach, because the offered trede becomes a contract condition and the sanction is 1.5 times the advantage you enjoyed.
How do they compare, item by item?
| Aspect | CO2-Prestatieladder | MKI |
|---|---|---|
| Unit of assessment | The organisation | The project design and its execution |
| Owner of the instrument | SKAO, a private scheme | An LCA method, with buyers prescribing how it is calculated |
| What you produce | An audited annual greenhouse gas inventory and a certificate or projectverklaring | A calculated MKI value with the LCA behind it |
| Who verifies it | An accredited certifying body | The buyer, against its own protocol for calculating and substantiating the value |
| How Rijkswaterstaat scores it | A fictieve korting, a notional reduction of the bid sum: 2 percent for trede 1, 4 percent for trede 2, 6 percent for trede 3 under Handboek 4.0 | A quality criterion inside the BPKV assessment. Bids with a lower MKI value score better |
| Where the numbers come from | Your own energy, fleet, purchasing and supply chain data | Material and product data of a specific design, with EPD-grade inputs |
| How often it changes | Annually, at audit | Per bid, per design iteration |
| Scope of what it covers | Greenhouse gases, in CO2 equivalents | A basket of environmental impact categories, not only carbon |
| What happens after award | The declared trede becomes a contract condition and is checked during execution | The value must be substantiated and monitored as the buyer's protocol requires |
The last row of the table is where the two instruments feel most similar and are still not. Both follow you into execution. One follows you as a company obligation, the other as a design obligation.
Do they really appear in the same tender?
Yes, at Rijkswaterstaat, and that is the source of most of the confusion.
Rijkswaterstaat names three standard sustainability instruments in its GWW procurement, meaning grond-, weg- en waterbouw: sustainability requirements written into the contract, the CO2-Prestatieladder and the MKI. The last two carry award weight and sit inside the same BPKV assessment, beste prijs-kwaliteitverhouding. Rijkswaterstaat says the MKI is used on a large number of projects rather than all of them, and does not publish a rule that either instrument appears in every tender.
So a bid team can be simultaneously assembling an organisational inventory for the trede it declares and an LCA for the design it is offering, using different people, different data and different software, against the same submission deadline. Treating that as one workstream is how firms end up with an MKI value they cannot substantiate or a trede they cannot prove.
Does a good MKI value substitute for a trede?
No. They are separate criteria and neither is an alternative to the other.
The mistake usually runs in one specific direction: a contractor with strong low-carbon design capability assumes the resulting MKI performance demonstrates its CO2 management and will carry the Ladder criterion too. It does not. The Ladder audit asks about your own scope 1 and 2 emissions, your reduction goals, your key roles and, from trede 2, your quantified scope 3 and your klimaattransitieplan, the climate transition plan. None of that is evidenced by a low MKI on a road surface.
The reverse mistake is rarer and equally wrong. A trede 3 certificate says nothing about the environmental performance of the asphalt you are proposing.
What changed in 2026, and what changes in 2027?
Both instruments moved recently, and on the same day at Rijkswaterstaat.
On 1 July 2026 Rijkswaterstaat brought Handboek 4.0 of the Ladder into its aanbestedingsleidraad, for procurements published on TenderNed after that date, weighting the treden at 2, 4 and 6 percent. Procurements published before that date stay under Handboek 3.1, where a 4.0 certificate was accepted but still scored against the five niveaus. On the same date MKI protocol 5.0 took effect and started going out with new tender documents. Its main changes: contractually prescribed end-of-life scenarios lead, so released materials are no longer counted separately as a positive contribution; transport values for inland and sea shipping were updated; proof rules were simplified where equipment contributes little and extended for zero-emission equipment; and Rijkswaterstaat states explicitly that category 1 and 2 LCAs from the Nationale Milieudatabase do not automatically satisfy its contract requirements.
From 2027 the European A2 weegset replaces A1 for projects published on TenderNed, taking the calculation from 11 to 19 environmental impact categories, adding water scarcity, particulate matter, ionising radiation and land use among others. Rijkswaterstaat expects MKI values to become on average roughly twice as high and says A1 and A2 results are not comparable one to one. Running projects keep the data versions fixed in their contracts, and DuboCalc 8.1, rebuilt to handle A2, has been released. Rijkswaterstaat says only that this applies to projects published from 2027, without naming a day.
Read that A2 change carefully. It does not mean designs get worse. It means the numbers get bigger and your historical MKI benchmarks stop being a guide to what a competitive value looks like.
Which one applies to you?
Work it out per procurement rather than in general.
If you bid for Rijkswaterstaat GWW work, assume both are possible and check the documents for each tender. If you bid where the Ladder is an award criterion and no MKI is requested, you have one instrument. If you supply products into somebody else's design rather than bidding the design yourself, the MKI question reaches you as a request for product data rather than as a criterion you are scored on, and the Ladder question may not reach you at all.
One thing that holds in every case: the Ladder never produces an MKI value and never asks for one. If a supplier or an adviser tells you their carbon accounting work will deliver both, that is the error the fact base flags as the most common in this area.
Where does each piece of work actually sit?
The Ladder half is organisational carbon accounting: an annual inventory a certifying body can trace, scope 1 and 2 at trede 1, quantified scope 3 and a klimaattransitieplan at trede 2. The Hedgehog platform names the CO2-Prestatieladder among its reporting outputs, carries over 20,000 spend-based and activity-based factors you can supplement with supplier-specific data, and reports 5,000+ users on its platform page. The limitation to plan around when two instruments run in parallel: Hedgehog has few integrations with other software today, and a mid-market reviewer on G2 asked for more in June 2026, so material and design data living in an LCA tool is not going to flow across on its own.
The MKI half is life cycle assessment work in a validated calculator against the buyer's protocol, with product-level data behind it. It is a different discipline with a different deliverable. If you are sorting out which half you are actually short of, that is a scoping conversation rather than a purchase: carbon footprint consulting for the organisational side, scope 3 consulting where trede 2 is the constraint. For the scheme itself, start with our introduction to the CO2-Prestatieladder for SMEs.
Sources: Rijkswaterstaat duurzaam inkopen and DuboCalc pages, Rijkswaterstaat news of 18 March 2026 and 21 May 2026, SKAO scheme pages and Overgangsregeling 3.1-4.0 v1.1 of 1 July 2025, read on 28 August 2026. Hedgehog platform and Hedgehog on G2, both read on 27 August 2026. Page verified 17 September 2026.
Facts on this page were last verified on 2026-09-17.
