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

What is Environmental Product Life Cycle
Assessment
• A tool to support environmental decision making
• Quantification of energy, material and waste flows over the product’s whole life cycle
• Evaluation of environmental impacts of those flows
INVENTORY
ANALYSIS
GOAL
DEFINITION
AND
SCOPING
IMPACT
ASSESSMENT
IMPROVEMENT
ASSESSMENT
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Helsinki University of Technology 2

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
Systems Analysis
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Helsinki University of Technology 3

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
Systems Analysis
Laboratory
Helsinki University of Technology 4

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
Systems Analysis
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Helsinki University of Technology 5

Product Life Cycle Assessment and System
Boundaries
Natural environment
Product system
Energy production and conversion
Raw-materials acquisition
Manufacture Distribution
Ancillary materials
Re-use
Recycling
System boundary
Use
Disposal
Landfill
Incineration
Systems Analysis
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Helsinki University of Technology 6

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
Systems Analysis
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Helsinki University of Technology 7

Impact Categories
POTENTIAL ENVIRONMENTAL IMPACT
Resource depletion
Energy and materials
Land (incl. wetlands)
Water
Human health impacts
Impacts in work environment
Toxicological impacts (excl. work environment)
Non-toxicological impacts
(excl. work environment)
Ecological impacts
Acidification
Depletion of stratospheric ozone
Ecotoxicological impacts
Eutrophication
Global warming
Habitat alterations and impacts on biological diversity
Photo-oxidant formation
Systems Analysis
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Helsinki University of Technology 8

Improvement Assessment
• Systematic search for effective ways to reduce the total environmental load
– Ensure that improvement in one part of the product’s life cycle doesn’t lead to larger increase of impacts in the others
Systems Analysis
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Helsinki University of Technology 9

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
Systems Analysis
Laboratory
Helsinki University of Technology 10

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
Systems Analysis
Laboratory
Helsinki University of Technology 11

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?
Systems Analysis
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Helsinki University of Technology 12

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
Systems Analysis
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Helsinki University of Technology 13

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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Helsinki University of Technology 14

Goal
Value Tree for Beverage Packaging
Main attributes Sub-attributes Alternatives
Economy
Investments
Employment
Competition
Logistics
4 FIM / L
Packaging system
Consumer
Safety
Price
Ease of use
1 FIM / L
Systems Analysis
Laboratory
Helsinki University of Technology
Environment
LCA inform ation
Resource depletion
Ecological impacts
Human health impacts
0 FIM / L
15

Decision Analysis in Impact Assessment:
Weighting 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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Helsinki University of Technology 16

A Compromise: Weights as a Function of the Impact Range
• Motivation: w i 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, w i
( r i
)
– w i
= W i
* r i
/ R i
, if the value function is linear
Systems Analysis
Laboratory
Helsinki University of Technology 17

Dynamic Weights in Case of Linear Value
Function
Va lu e v(Best)=1
1.0
W corresponds to the range R w corresponds to the range r w = W*r / R W
0.0
Actual range, r v(Worst)=0
Im p a c t
Reference range, R
Systems Analysis
Laboratory
Helsinki University of Technology 18

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
Systems Analysis
Laboratory
Helsinki University of Technology 19