Life Cycle Assessment
A product-oriented method
for sustainability analysis
UNEP LCA Training Kit
Module e – Impact assessment
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ISO 14040 framework
Life cycle assessment framework
Goal
and scope
definition
Direct applications:
Inventory
analysis
Interpretation
-
Product development
and improvement
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Strategic planning
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Public policy making
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Marketing
-
Other
Impact
assessment
Source: ISO 14040
Life cycle impact assessment
• ISO: Phase of life cycle assessment aimed at understanding
and evaluating the magnitude and significance of the potential
environmental impacts of a product system
– International Standard ISO 14042
– Technical Report ISO/TR 14047
• The third phase of an LCA
– LCIA
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Contents
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•
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The principle of
characterisation
Selection of impact categories,
category indicators and
characterisation models
Classification
Characterisation
Optional elements
– normalisation
– grouping
– weighting
– data quality analysis
The principle of characterisation (1)
• CO2 and CH4 both contribute to climate change
• Global Warming Potential (GWP): measure for climate change
in terms of radiative forcing of a mass-unit of greenhouse gas
• Example calculation:
impact category
– 5 kg CO2
– 3 kg CH4
– 1 x 5 + 21 x 3 = 65
characterisation
– 68 kg CO2-eq
factor
GWP = 1
GWP = 21
category indicator result
category indicator
The principle of characterisation (2)
• Simple conversion and aggregation:
IndicatorResultcat 
 CharFactcat ,subs  InventoryResultsubs
subs
GWP (1 and 21)
5 and 3 kg
CO2 and CH4
68 kg CO2-eq
climate change
IPCC climate model
infrared radiative forcing
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The principle of characterisation (3)
• Two main groups of choice for indicator
– midpoint-oriented (CML-IA, EDIP, TRACI, …)
– endpoint-oriented (Eco-indicator 99, Eco-scarcity, EPS, …)
• And ongoing efforts to combine/harmonize
– midpoint and endpoint (Impact 2002+, Recipe, ...)
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The principle of characterisation (4)
Example
Cd, CO2, NOx, SO2, etc.
(kg/functional unit)
Life cycle inventory results
Impact
category
LCI results assigned to
impact category
Acidification
Acidifying emissions
(NOx, SO2, etc.
assigned to acidification)
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Characterisation model
Category indicator
Proton release
(H+ aq)
Environmental relevance
Category endpoint(s)
- forest
- vegetation
- etc.
The principle of characterisation (5)
• Structure of endpoint-oriented model (Eco-indicator 99)
Inventory table
Resource use
Land use
Modelling of
cause and
effect chain,
using natural
sciences
Damage to
resources
Damage to ecosystem quality
Emissions
Damage to human
health
Valuation of
severity of
damages
Indicator
Impact categories, category indicators,
characterisation models (1)
• Impact category
– ISO definition: class representing environmental issues of
concern to which LCI results may be assigned
• Examples:
– climate change
– acidification
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Impact categories, category indicators,
characterisation models (2)
• Category indicator:
– ISO definition: quantifiable representation of an impact
category
• Examples:
– infrared radiative forcing
– proton release
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Impact categories, category indicators,
characterisation models (3)
• Characterisation model:
– non-ISO definition: mathematical model of the impact of
elementary flows with respect to a particular category
indicator
• Examples:
– IPCC model for global change
– RAINS model for acidifying substances
• Provides the basis for a characterisation factor
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Impact categories, category indicators,
characterisation models (4)
• Characterisation factor:
– ISO definition: factor derived from a characterisation model
which is applied to convert the assigned LCI results to the
common unit of the category indicator
• Examples:
– GWP
– AP
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Impact categories, category indicators,
characterisation models (5)
• Impact categories, characterisation methods and
characterisation models: some baseline examples
impact category category indicator characterisation model characterisation
factor
abiotic depletion ultimate reserve irt Guinee & Heijungs 95
ADP
annual use
climate change infrared radiative
IPCC model
GWP
forcing
stratospheric
strat. ozone
WMO model
ODP
ozone depletion breakdown
human toxicity
PDI/ADI
Multimedia model, e.g.
HTP
EUSES, CalTox
ecotoxicity
PEC/PNEC
Multimedia model, e.g.
AETP, TETP, etc.
(aquatic,
EUSES, CalTox
terrestrial etc.)
photo-oxidant
trop. ozone
UNECE Trajectory model POCP
formation
formation
acidification
deposition/ac.critical RAINS
AP
load
...
...
...
...
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Impact categories, category indicators,
characterisation models (6)
• LCA has essentially a flow character:
– emissions/ resource extractions in kg per functional unit
• Impacts have therefore a similar character:
– climate change/toxicity/depletion/etc. per functional unit
• Some impacts do not fit well:
– loss of biodiversity/introduction of GMOs/etc.
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Classification (1)
• ISO definition: assignment of LCI results to impact categories
• Example: CO2 and CH4 are assigned to climate change
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Classification (2)
Impact category
Incandescent lamp
Fluorescent lamp
CO2 to air
800000 kg
50000 kg
CH4 to air
230 kg
24 kg
3g
20 g
Climate change
Ecotoxicity
Copper to water
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Characterisation (1)
• ISO definition: calculation of category indicator results
• Example: 5 kg CO2 and 3 kg CH4 yield 68 kg CO2-eq
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Characterisation (2)
• Formula:
IndicatorResultcat 
 CharFactcat,subs  InventoryResultsubs
subs
• Unit of characterisation result:
– kg CO2-eq (climate change)
– kg SO2-eq (acidification)
– …
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Characterisation (3)
• Example of a characterisation table
Impact category
Incandescent lamp
Fluorescent lamp
Climate change
120000 kg CO2-eq
40000 kg CO2-eq
Ecotoxicity
320 kg DCB-eq
440 kg DCB-eq
Acidification
45 kg SO2-eq
21 kg SO2-eq
Depletion of resources
0.8 kg antinomy-eq
0.3 kg antinomy-eq
etc
…
…
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Normalisation (1)
• ISO definition: calculation of the magnitude of category
indicator results to reference information
• Reference information (over a given period of time):
– area (e.g., France, Europe, the world)
– person (e.g., a Danish citizen)
– product (e.g., the most frequently used product)
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Normalisation (2)
• Aim: better understand the relative magnitude for each
indicator results of the product system under study.
– checking for inconsistencies
– providing and communicating information on the relative
significance of the indicator results
– preparing for additional procedures
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Normalisation (3)
• Formula:
Normalized IndicatorR esult cat 
IndicatorR esult cat
ReferenceV alue cat
• Unit of normalisation result: year
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Normalisation (4)
• Example of a normalisation table
Impact category
Incandescent lamp
Fluorescent lamp
Climate change
1.210-11 yr
410-12 yr
Ecotoxicity
1.610-10 yr
2.210-10 yr
Acidification
910-11 yr
4.210-11 yr
Depletion of resources
2410-12 yr
910-13 yr
etc
…
…
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Grouping (1)
• ISO definition: assigning impact categories into one or more
sets
• Sorting: grouping on a nominal basis
– e.g., global versus regional
• Ranking: grouping on an ordinal basis
– e.g., high, medium and low priority
– based on value choices
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Grouping (2)
• Example of the results of grouping
Impact category
Incandescent lamp
Fluorescent lamp
Climate change
1.210-11 yr
410-12 yr
Depletion of resources
2410-12 yr
910-13 yr
910-11 yr
4.210-11 yr
Global
Regional
Acidification
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Weighting (1)
• ISO definition: converting and possibly aggregating indictor
results across impact categories using numerical factors
– based on value-choices
– ISO: “weighting shall not be used for comparative
assertions disclosed to the public”
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Weighting (2)
• Basis for weighting factors:
– monetary values
• willingness-to-pay
• damage costs
• reduction costs
– distance-to-target methods
– panel methods
• expert panels
• non-expert panels
– ...
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Weighting (3)
• Some methods that include weighting
– ecopoints/ecoscaricity
– Eco-indicator 99
– EPS
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Weighting (4)
• Formula:
WeightedIndex 
• or
 WeightingFactcat  IndicatorResultcat
cat
 WeightingFactcat  NormalizedndicatorResultcat
cat index:
• Unit of weighted
– year (when based on normalized results)
– euro, dollar, etc. (when based on monetary valuation)
– but often renamed: ecopoints, millipoints, ELU, etc.
WeightedIndex 
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Weighting (5)
• Example of the results of weighting
Weighed index
Incandescent lamp
Fluorescent lamp
Weighted index
8.510-10 yr
1.410-10 yr
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Data quality analysis
• Understanding the significance, uncertainty and sensitivity of
the LCIA results
• Suggested techniques:
– gravity analysis
– uncertainty analysis
– sensitivity analysis
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