Evaluation methodologies of results can be divided into different types of approaches; let's see some of them:
1. Proxy Approach: To describe the environmental impact, a quantitative measure or a limited number of parameters are used, such as material handling or energy consumption associated with the production system. This is an arbitrary choice that provides a partial view of the environmental profile of a system. The selection of significant parameters must be made in agreement with the analysis objectives, proving useful in case the life cycle study has been conducted solely to assess a specific impact. Otherwise, the selected category will hardly be representative.
2. Monetization: This approach relates to the concept of environmental economics with a dual aspect: the value of the environment can be estimated by considering the expenses necessary to control environmental damages or by considering the willingness to pay manifested in order to avoid the impacts identified in the LCA. In the first case, it is called Environmental Control Costs, while the second is defined as Environmental Damage Costs.
3. Distance to Target: This approach explicitly incorporates social preferences into the formulation of weighting coefficients, using national and international legislative standards or environmental quality objectives.Example: If the concentration of a pollutant in the environment is 1.1 mg/mc and the standard is 1 mg/mc, the weight to be assigned to the impact is 10%, as the concentration exceeds the expected target by 10%. The main problem related to this approach is that many standards are formulated not only based on scientific considerations but also regulated by technical limitations, feasibility of controls, and political factors. Therefore, the results may vary for each nation.
4. Panel Approach: Weighting coefficients are calculated by a group of experts capable of evaluating the importance of various impact categories. These evaluations can be conducted using various methods related to social sciences, and the group of individuals can be selected according to different criteria (expert group, consumer group, governmental group, etc.), in order to reflect relevant scientific and social opinions.
5. Technology Approach: This methodology is based on known and used technology for the reduction of specific emissions into the environment.
Below is a list (not exhaustive) of some normalization and weighting methodologies used in the LCIA phase for each approach described above:
- Energy Requirement (1994), USA : The equivalence principle is based on energy requirements. Approach #1
- Abatement Energy (1994), Netherlands: The equivalence principle is based on the total energy requirement needed to reduce environmental loads. Approach #5.
- Abatement Costs (1992), Netherlands: The equivalence principle is based on the costs of emission abatement in accordance with national objectives. Approach #2 and 3.
- Eco Indicator 95 (1995), Netherlands: The equivalence principle is based on values exceeding sustainable objectives with optional subjective weighting. Approach #3.
- Expert Panel Prioritization (1996), Germany: The equivalence principle is based on the comparison between production systems using a qualitative assessment of the data and a score calculated by a group of experts. Approach #4.
