Eco-indicator 99

The principles explained

Weighting is a controversial step in  impact assessment. Taking weighting as the starting point of the Eco-indicator 99, we worked top down to complete the method.

This is in contrast with the "bottom up" approach found in the traditional theme oriented methods, where a panel can be confronted with ten or more abstract environmental themes to weight. New damage models and 3 perspectives were developed to complete the method.

• Weighting
• General outline
• Acknowledgements

Weighting

In the project, the weighting step was performed by a panel in a careful procedure. All efforts were made to make this step as straightforward as possible.

Key requirements for an optimal weighting step are:

• The items to be weighted by the panel are not too abstract.
• The number of items is limited.
• The items include all relevant environmental effects.

Damage categories

The need to simplify the weighting procedure meant we needed to define the "Eco" we wanted to "indicate" first. The following damage categories (endpoints in ISO terminology) were defined:

• Damage to Human Health
• Damage to Ecosystem Quality
• Damage to Resources

New damage models were developed that link inventory results into three damage categories.

Weighting results

The result of the panel procedure is that Human Health and Ecosystem Quality are considered to be of almost equal importance, while Resources are considered to be half as important.

The figure left gives an overview of the structure of the eco-indicator 99 methodology (click to enlarge).

In life cycle impact assessment three types of models are used:

• Modeling of Technosphere: in the inventory phase.
• Modeling of Ecosphere: in the impact assessment phase.
• Modeling of Valuesphere: in weighting and ranking, and to deal with unavoidable value choices.

We use the term "sphere" to indicate that the Eco-indicator 99 integrates different fields of science and technology. It is important to be aware that the spheres have very different characteristics, as explained below.

The most fundamental problem in LCA is that when value choices have to be made, a single truth simply does not exist. For example, a substance that is classified as "possible carcinogenic" can be seen as extremely dangerous by one person, whilst another would not be bothered at all. 

To deal with this problem, three different perspectives were developed. The differences between them can be seen in the results of the European LCA. One perspective was chosen to be the default.

Acknowledgements

The Eco-indicator 99 has been developed by a team of experts between 1997 and 1999. The project was commissioned by the Dutch Ministry of Urban Planning, Housing and the Environment (VROM) as part of the Product Oriented Environmental Management policy. Click here for the preface in the report.