Environmental News, 78 – Impact categories, normalisation and weighting in LCA – 3. Application of normalisation references and weighting factors

Impact categories, normalisation and weighting in LCA

3. Application of normalisation references and weighting factors

The strategy so far has been to normalise global impacts globally as well as regional and local impacts regionally, based on Danish conditions. In the present project, new normalisation references have been developed for global, regional and local effects. For global warming and stratospheric ozone depletion global normalisation references have been calculated. For photochemical ozone formation, acidification, nutrient enrichment, human toxicity and ecotoxicity Danish and European (EU-15) normalisation references have been calculated and worldwide normalisation references have been extrapolated.

As regards weighting updated figures are also provided. In some instances the new figures also include regional, national and global political targets. For global warming there are targets for industrialised countries as well as developing countries.

The updated and extended normalisation references and weighting factors are presented in Table 3.1.

The basic intentions with updating and extension of the normalisation references are that:

Global effects are (still) normalised globally based on global figures
Regional effects are normalised regionally based on reliable European figures
Worldwide normalisation references are available for the local and regional effects if found appropriate; the worldwide normalisation references are based on extrapolation

Furthermore, the new set of normalisation references allows the user to choose a normalisation reference adjusted to a specific purpose. These new possibilities give occasion for choosing, the main question being when and how to apply specific normalisation references.

First of all, the intention with updating the weighting factor is still to allow the weighting since the target year of 2000 in the original EDIP is reached. Secondly, the goal of the new weighting factors is to provide more possibilities since more factors for the different impact categories are provided. The new possibilities give occasion for choosing, e.g. if your company is situated in an industrialised country and you choose to place your production in a developing country. If you want to weight your normalised results you can choose either to take the weighting factor for the developing countries (e.g.) for global warming or you can choose the weighting factor for the country. Both options are possible (and allowed), but in any case you have to argue for your choice.

Table 3.1 Normalisation references and weighting factors, original EDIP₉₇ and update (Global, EU-15, and Denmark)

Click here to see the table.

3.1.1 When and how to apply specific normalisation

For use of the updated EDIP₉₇ normalisation references, the following recommendations are given for normalisation of the LCA results:

For global impacts (global warming and stratospheric ozone depletion) always use the worldwide normalisation reference in the base case analyses
- EU-15 or Danish normalisation references can be used in a sensitivity analyses to mirror the relative importance in highly developed industrial countries with a large contribution per capita
For regional impacts (acidification, photochemical ozone formation and nutrient enrichment) and local impacts (ecotoxicity, human toxicity) use the EU-15 normalisation reference as the base reference
- If the main impacts are known to take place in a given region, for which a more appropriate normalisation reference is available, this may be used as the base reference, clearly reporting this deviation from the general recommendation. As an example, for energy consuming devices used in Denmark, the main impacts can be assumed (or verified) to arise in Denmark and accordingly, the applied normalisation reference for the energy-related impact categories could equally well be Denmark. For energy consuming products produced in Denmark and used (primarily) outside of Europe, the worldwide normalisation references could be applied. It should however be noted that the European reference probably gives the most precise results if the area of use predominantly is industrialised countries and this is therefore also an option.
Where relevant, use normalisation references for other geographical regions as an element in the sensitivity analyses, acknowledging the inherent uncertainties. The case used in the report is an example of this, where the generally recommended normalisation reference for EU-15 could be supplemented with the Danish normalisation references in a sensitivity analysis. This is especially beneficial in relation to nutrient enrichment, human toxicity and ecotoxicity, all of which impacts have a local as well as a regional element.

The recommendations above reflect the inherent uncertainties in normalisation, especially if the step has a broad scope. Obviously, the more is known about the product (system) investigated as regards the geographical extent of its potential impacts, the more precisely the normalisation step will mirror the relative importance of different impacts.

The recommendations are a modification of earlier recommendations for EDIP₉₇, where Danish normalisation references were recommended for regional and local impacts. The suggested shift to the EU normalisation reference is justified by the better scope for many industrial products, combined with the fact the EU-normalisation references are of an acceptable quality.

3.1.2 Example

In the following sections on specific impact categories, the general recommendations above are exemplified in a specific case. The case, an LCA of a refrigerator, is presented in short in Chapter 11, including the figures for impact potentials.