The Environmental Cost Indicator (ECI) (in Dutch: Milieukostenindicator - MKI) is a single-score metric used to express the environmental impact of construction materials and products in monetary terms. It is specific to the Dutch construction sector and is central to environmental assessments, tenders, and regulations. Recent updates to the NMD Bepalingsmethode and the shift from EN15804+A1 to EN15804+A2 have led to new ECI weighting factors. These changes affect how ECI scores are calculated and interpreted. This article answers the following questions:
What are ECI weighting factors?
What’s the difference between the new and old ECI scores?
Why are new ECI scores required?
How to (re)calculate ECI scores according to the NMD in Ecochain software?
Feel like you're missing information? This article is connected to the following articles; check them out if you want to learn more:
On the LCIA phase
On LCIA methods
On Single Score
On the latest NMD database (NMD v3.9)
What are ECI weighting factors?
Environmental cost indicator (ECI), referred to in Dutch as Milieukostenindicator (MKI) weighting factors convert impact category scores from a Life Cycle Assessment (LCA) into a single ECI score, measured in euros. This expresses environmental impacts in monetary terms, making it easier to compare different products and projects.
The ECI is specific to the Netherlands, other countries do not currently use a similar single-score approach. By summing euro values across impact categories and lifecycle stages, the total ECI of a project can be determined.
The new ECI weighting factors
The latest ECI weighting factors for the +A2 impact categories were developed through scientific research by CE Delft and approved in late 2023 by the Ministry of Infrastructure and Water Management and the Ministry of the Interior and Kingdom Relations.
Key changes in the +A2 version:
Comparison with +A1: The +A1 (Table 1) and +A2 (Table 2) weighting factors cannot be directly compared due to differences in impact categories and their units.
Higher impact for key categories: The weighting factors for global warming and depletion of abiotic raw materials have significantly increased.
Alignment with Dutch climate goals: The updated CO₂ pricing aligns with national emission targets, and the higher valuation of raw material depletion promotes circular economy principles such as reduce, reuse, and recycle.
These changes aim to drive more sustainable decision-making by encouraging the use of materials and processes that reduce environmental impact. Table 1 showcases the old weighting factors, and Table 2 showcases the new weighting factors.
Table 1: Old ECI weighting factors
Table 2: New weighting factors.
* “Climate change - total” is the sum of indicators “climate change - fossil”, “climate change- biogenic”, and “climate change - land use and land use change”.
Caution - Comparing old and new ECI weighting factors: Weighting factors cannot be directly compared due to differences in impact category units and differences in the amount and types of impact categories. However, the effect of the ECI weighting factors for global warming and depletion of abiotic raw materials are comparable and are significantly higher than before.
What’s the difference between the new and old ECI scores?
To help illustrate the impact of the new ECI score, we compared the old and new ECI scores for the same product: an EPS insulation board with a lamination layer.
The product was modeled using a cradle-to-gate scope (according to EN15804), which includes: A1: Raw material supply, A2: Transport, A3: Manufacturing.
Example calculation
Example calculation
When comparing the total cradle-to-gate ECI scores (sum of A1–A3) between the old and new versions, the new ECI was 97.5% higher in this example (Figure 1). However, the relative contribution of each module remains nearly identical:
A1 (raw materials): ~89% of total impact
A2 (transport): Negligible
A3 (manufacturing): Remainder
Figure 1: Contribution of life cycle modules (A1 - A3) to total cradle-to-gate (new and old) ECI.
The composition of the ECI also changed (Figure 2). In this example:
The share of climate change impacts increased from 58% to 74% of the total ECI.
New impact categories introduced in the +A2 method (e.g., particulate matter formation) contribute significantly to the ECI.
Figure 2: Impact category scores and contributions to the total ECI, with old and new weighting factors.
Why are new ECI scores required?
The Environmental Cost Indicator (ECI or MKI) is a key part of sustainability assessment in the Dutch construction sector. In recent years, new regulations and updates to the NMD Bepalingsmethode have made it necessary to transition from the old ECI (based on EN15804+A1) to the new ECI (based on EN15804+A2). This shift improves alignment with European standards and prepares the sector for stricter environmental targets.
Regulatory shift toward the new ECI
Until now, Dutch companies have been required to report both old and new ECI scores to comply with national and European rules. This double reporting, for the old ECI and the new ECI, has created complexity for LCA practitioners.
Starting in July 2025, only the new ECI will be required for government tenders and regulatory reporting. The requirement to report both versions will be phased out, streamlining compliance across the industry.
Stricter sustainability targets for buildings
The Dutch government has set ambitious targets for the environmental performance of new buildings. Current ECI limits are:
0.5 €/m² floor area for new housing
0.85 €/m² floor area for new office buildings
These limits are still based on the old ECI. As the transition to the new ECI becomes official, these thresholds will be translated to equivalent values using the new method. The translated targets will appear numerically higher but will reflect the same level of ambition.
Once adopted, these new ECI targets will be formally included in Dutch building regulations. Construction companies should already begin preparing for these lower-impact targets under the new methodology.
Relevance to foreign companies
Can foreign companies calculate the new ECI based on EN15804+A2? Yes, but only if they follow the NMD assessment method.
Foreign construction companies that want to participate in Dutch construction tenders must provide the ECI for their products. While an EPD doesn’t need to be listed in the NMD database, the underlying LCA must fully comply with the NMD method. If not, the calculated ECI is invalid.
Caution - NMD compliance: Following EN15804+A2 alone is not enough to comply with NMD requirements. For example, the GaBi database is accepted under EN15804+A2 but not allowed under the NMD method. This means you cannot reuse existing +A2 scores to calculate a valid new ECI for the Dutch context.
To calculate a valid new ECI as a foreign company:
Follow the NMD method when modeling your product.
Prepare your model for the upcoming NMD update, and calculate your +A2 scores accordingly.
How to (re)calculate ECI scores according to the NMD in Ecochain software?
Ecochain software are up-to-date with the latest changes to the NMD Bepalingsmethode and the preferred ECI / MKI weighting factors. This article offers an overview of the latest NMD database (NMD v3.9), including how to decide between MKI weighting factors and how to apply them in Ecochain Mobius and Ecochain Helix.
Curious how your new ECI score may look? Use our Excel ECI calculator to preview based on your existing data.
Download the ECI Calculator in Excel. Ecochain_New and old ECI analysis template.xlsx
Next steps
The new ECI weighting factors significantly increase ECI scores, place greater emphasis on global warming and raw material depletion, and encourage more circular design decisions. From July 2025, only the new ECI (based on EN15804+A2) will be accepted for Dutch construction tenders and regulatory reporting. Companies with existing EPDs must ensure they include +A2 scores by 2025. You can calculate your new ECI using Ecochain Mobius or Ecochain Helix. Portfolio LCAs can already be prepared in Helix using current NMD databases.
References
[4] https://milieudatabase.nl/nl/actueel/nieuws/aankondiging-voornemen-wijzigingen-bepalingsmethode/
