How to Benefit from Decision Analysis in Environmental Life Cycle Assessment

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How to Benefit from Decision Analysis in
Environmental Life Cycle Assessment

• Pauli Miettinen and Raimo P. Hämäläinen
• Otakaari 1 M, FI-02150 Espoo
• E-mail raimo_at_hut.fi
• http//www.hut.fi/Units/Systems.Analysis
• European Journal of Operational Research, Vol.
  102, 1997, pp. 279-294.

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What is Environmental Product Life Cycle
Assessment

• A tool to support environ-mental decision making
• Quantification of energy, material and waste
  flows over the products whole life cycle
• Evaluation of environmen-tal impacts of those
  flows

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LCA Organisations and Journals

• Organisations
• ISO - International Standardisation Organisation
• SETAC - Society for Environmental Toxicology and
  Chemistry
• Journals
• Chemosphere
• Environmental Toxicology and Chemistry
  International Journal of Life Cycle Assessment
• Journal of Cleaner Production

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Goal Definition and Scoping

• Planning part of an LCA study
• Purpose
• Scope
• Basis for comparison, i.e. the functional unit
• Data collection and quality assurance plan
• Determines the following phases

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Inventory Analysis

• Quantification of inputs and outputs crossing the
  system boundary
• Problem areas
• Data amount and quality
• Cut-off rules
• Allocation
• Result is a long list of inputs and outputs of
  different nature
• Difficult to interpret

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Product Life Cycle Assessment and System
Boundaries
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Impact Assessment

• Interpretation of the inventory results
• Methods Critical volumes, EPS, Eco-scarcity,
  Tellus,...
• Environmental theme method classification,
  characterisation, (normalisation) and valuation
• How far to aggregate the inventory results?
• One figure or contribution to a set of
  environmental problems
• Objective and subjective information should be
  used separately

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Impact Categories
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Improvement Assessment

• Systematic search for effective ways to reduce
  the total environmental load
• Ensure that improvement in one part of the
  products life cycle doesnt lead to larger
  increase of impacts in the others

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Three Types of Data in LCA

• Process data for inventory analysis
• Material and energy requirements as well as
  emissions per unit output
• Impact data for transforming the inventory
  results to environmental impacts
• Impacts of substances to different environmental
  problems
• Preference data for planning the study and
  interpreting the results
• Values and preferences of the actual decision
  makers
• Overlooked in the current LCA practice

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Role of Decision Analysis in Life Cycle
Assessment (LCA)

• Needed in the subjective steps
• Goal definition and scoping
• Impact assessment (valuation)
• Helps planning the study to meet the needs of the
  decision makers
• Increases the transparency of public decision
  making

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Decision Analysis in Goal Definition and Scoping
Understanding the Process

• Who are the DMs?
• What is the related decision or choice problem?
• What are the alternatives?
• What are the attributes, i.e. the impact
  categories?
• What data will be needed?

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LCA Study of Eight Finnish Beverage Packaging
Systems (Virtanen et al. 1995)

• Objectives
• General to produce environmental information for
  political and economical decision making
• Specific To support in an environmental tax
  decision concerning beverage in aluminium cans
• The study was unable to show the best alternative
• We analysed in retrospect
• How LCA information was used in decision making
• What benefits might have come from the explicit
  use of decision analysis

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Benefits from Value Tree Presentation and
Explicit Prioritisation

• Seeing the decision problem in a general context
• Include also other dimensions than environment
• Identification of the decision alternatives
• Not the beverage packaging options but different
  tax levels
• Identification of data collection needs
• For example analysis of market shares resulting
  from different tax levels should have been done

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Value Tree for Beverage Packaging
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Decision Analysis in Impact AssessmentWeighting
the Impact Categories

• Impact weight should depend on
• General seriousness of the environmental impact
• How alternatives differ in each impact category
• General weights suggested by the LCA community
  not acceptable
• Address only part of the problem
• Do not change if the decision problem, i.e.
  alternatives change
• Weighting should be case specific
• Behavioral problems exist in weighting

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A Compromise Weights as a Function of the Impact
Range

• Motivation wi represents the importance of
  moving from the worst to the best outcome in the
  i th impact
• Should never be interpreted without referring to
  some specified change
• R and W are the reference range and weight
• The reference weights elicited by considering the
  reference ranges
• Weights explicitly as a function of the range,
  wi(ri)
• wi Wi ri /Ri, if the value function is linear

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Dynamic Weights in Case of Linear Value Function
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Conclusions

• LCA a promising tool for environmental
  management, especially in public use
• Important application area for decision analysis
• Goal definition and scoping value tree
  construction
• Putting the decision problem into overall context
• Understanding the components of the decision
  problem
• Impact assessment weights must depend on the
  attribute ranges
• Problem specific weighting
• Explicit functional dependency