CML method

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The CML method is an ecologically-oriented information and decision-making tool for creating a life cycle assessment in accordance with DIN EN ISO 14040.

Its development goes back to the Centrum voor Milieukunde (CML) of the University of Leiden . Here it was found in 1992 by Heijungs et al. (1992) published and fundamentally revised in 2000.

The aim of the CML method is the quantitative mapping "[...] of all direct material and energetic exchange relationships between the natural environment and the product system [...]" and thus tries to take greater account of the impact side.

method

The implementation of the CML method takes place in several steps, whereby first the data acquisition in the life cycle inventory is in the foreground and in the second step the aggregation over different impact categories is carried out. The quality of the result depends to a large extent on the care taken in quantifying the material flows.

Classification and characterization

In the first step in evaluating potential impacts, in addition to the specific goals and framework conditions, the balance area and its limits are also determined. Subsequently, all material and energy flows along the life cycle ( cradle-to-grave ) are recorded in terms of the life cycle inventory . The determined data is recorded as input and output parameters along the entire product life cycle. With the CML method, the impact assessment is carried out by means of an "impact-oriented classification" of the material and energy flows. For this purpose, the data are assigned to the following impact categories:

Normalization and weighting

In the next step, the aggregation takes place within the individual impact categories on the basis of so-called equivalence factors or weighting factors for the respective pollutants , which, if possible, are based on the assessment of internationally recognized bodies. The individual input and output variables are multiplied by the weighting factors and then the weighted quantities are aggregated for each impact category. For an overall assessment, the individual impact categories can still be weighted among one another and arranged within a ranking. So far, three approaches have been recommended in the literature:

  • NSAEL ( No significant adverse effect level ) method ( distance-to-target ):
Describes the total pollution of an impact category per year (Ei) depending on the just tolerable pollution (Ri).
Determination of the weighting factors by a selected group of people. The same information and a consensus regarding the evaluation criteria must be available. Low validity of this approach, as so far only carried out on small, non-representative groups.
Weighting factors are obtained taking into account target values ​​specified by Dutch environmental policy.

Environmental policy principles usually form the basis for the individual weighting factors. After determining the weightings for the individual categories, approaches for an ecological improvement can be worked out according to the results.

Result

Ranking of the weighted categories (human toxicity, greenhouse effect, etc.). This depends on the amount of substance, the equivalence values ​​and the weighting method.

criticism

The separation into a scientific aggregation within the individual impact categories and a subjectively weighted overall assessment is to be assessed positively. In addition, the CML method corresponds to the national and international efforts for standardization , as it covers target definition, inventory analysis, impact analysis and assessment. It enables companies to use and design a wide range of options in the context of life cycle assessment. The comparability of different life cycle assessments is made difficult by the fact that, as a rule, not 100% of the same impact categories were selected.

Determining the data is usually the most difficult and time-consuming step in creating a life cycle assessment. When considering the entire life cycle as the system boundary for the life cycle assessment , compromises have to be made, since in many cases it is not possible to obtain all the necessary data and some of the data is estimated in practice, which impairs the accuracy of the results obtained. In general, the life cycle assessment was initially developed for traditional processes and products, which means that it can only be used to a limited extent in areas within very complex and still new sciences such as biotechnology .

The preparation of some life cycle assessments according to international standards can be time-consuming and costly.

application areas

The CML method is used when accounting for products, processes and companies. It was initially used to optimize packaging systems, but over time it was also extended to other processes. Using the CML method, B. important ecological value drivers are identified within the life cycle in order to develop strategies for a better ecological positioning of a company.

See also

Individual evidence

  1. ^ Edeltraud Günther: Ecology-oriented management. UTB, Stuttgart 2008, ISBN 978-3-8252-8383-4 , p. 292.
  2. ↑ a b Jeroen B. Giunée u. a .: Developing an LCA guide for decision support. In: Environmental Management and Health. Vol. 12, Iss. 3, 2001. MCB University Press, ISSN  0956-6163 , p. 301.
  3. ↑ Jeroen B. Giunée et al. a .: Handbook on Life Cycle Assessment. Operational Guide to the ISO Standards. Kluwer Academic Publishers, Dordrecht 2002, ISBN 1-4020-0228-9 , p. 5.
  4. ^ Edeltraud Günther: Ecology-oriented management. UTB, Stuttgart 2008, ISBN 978-3-8252-8383-4 , p. 321 f.
  5. ↑ a b c Heidi Adensam u. a .: How much environment does a product need? Study on the usability of life cycle assessments for process and product comparisons. ( Memento of the original from September 26, 2011 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 4.2 MB). Austrian Ecology Institute, 2000, p. 37 ff. Accessed June 3, 2012. @1@ 2Template: Webachiv / IABot / www.umweltbundesamt.at
  6. ↑ Beate Stahl: Comparison of methods and development of methods to solve the valuation problem. Dissertation at the University of Bremen. Production engineering department, 1998, p. 38 f.
  7. ↑ a b J. GM Kortmann u. a .: Towards a Single Indicator for Emissions. An Exercise in Aggregating Environmental Effects. University of Amsterdam, 1994.
  8. ↑ Arthur Braunschweig a. a .: Evaluation and further development of assessment methods for life cycle assessments . First results , University of St. Gallen, 1994, pp. 115–130.