Comparing Different Types Of Impacts And Evaluation Of Total Impact

In LCA terminology evaluation can be made in several ways, such as normalizing, ranking, sorting or weighting. Earlier the term 'valuation' was used instead of weighting, but ISO found the term 'weighting' to better represent all techniques that were used. Normalizing is a standard procedure in RA, where an estimated concentration that may occur in the environment is always compared to a reference concentration. In a way ranking and sorting are also standard procedures in RA and EIA, where the overall aim is to elucidate significant environmental impacts. Weighting is used systematically only in CBA and LCIA. In the standardization of

Figure 13.3 Relations between emissions and impacts may vary owing to location and other circumstances

LCIA, weighting has been a controversial step. ISO 14042 explicitly states that 'weighting shall not be used for comparative assertions disclosed to the public' (ISO 2000). 'Comparative assertions' are defined as 'claims of overall superiority'. In other words, the use of weight factors for evaluation is not sufficient to conclude that product A is superior to product B.

A cautious attitude is easy to understand if weighting results are seen as a 'verdicts' and if companies and responsible persons have limited ability to adapt to the 'law'. Representatives of the third world often mentioned LCIA and weighting in particular as a potential trade barrier. The industrial world might conceivably impose new requirements on the third world industry that it could not fulfill. However, if weighting is seen as comparing the overall outcome with different general environmental goals and public preferences, it may be less controversial (Bengtsson and Steen 2000). Those in favor of weighting claim that no choice between technical concepts can be made openly and transparently without weighting. If a formal weighting procedure is used the result is open for discussion and criticism. This is particularly valuable for a democratic process, as when the government develops guidelines for recycling or for use of some materials.

Economic evaluation, as in CBA, is common, but no less controversial. On one hand there is a wish to reach the vast number of decision makers who cannot understand and use environmental impact information unless it is expressed in economic terms. On the other hand, economic thinking has to a large extent put us where we are today in its inability to detect some of nature's core values. Is it possible to value what is priceless? A common criticism of economic valuation is based on the use of discounting. Discounting may significantly reduce the appearance of long-term effects such as global warming (see, for example, Azar and Sterner 1996)

Attitudes towards environmental changes vary considerably among people, sometimes with orders of magnitude. However, as with characterization factors, we are normally dealing with large technical systems influencing lots of people. Therefore the uncertainty decreases if we perform the analysis on the population level. A particular problem occurs when applying today's attitudes, which normally are available only from Western countries, to other cultures and future generations. As long as this is on a conscious level and reported in a transparent way, the problem may be handled, but there are many examples of technical projects that have not been sufficiently aware of local culture.

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