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UNIT 8
Impact Assessment
1.1 Objectives of lesson 8
The aim of this unit is to achieve the following points:
– understanding the general procedure of impact assessment,
– having a clear idea about an impact assessment method,
– learning about the framework for toxicity assessment (presential course).
What should be assimilated:
At the end of this lesson, you should be able to answer the following questions:
– Why isn't it possible to determine the best scenario just after LCI?
– What do you have to define if you want to compare a bicycle with a pair of jeans,
for example?
– What are the different steps of LCIA? Give a short description of them.
– How can you value social Weighting factors?
1.2 LCA Steps, where are we ?
Goal
definition
Inventory of
extractions and
emissions
Interpretation
Impact
assessment
We previously have looked at the goal definition, defined our system and its function.
The elementary flows crossing the system boundaries have been determined. They
enabled to get the emissions and extractions inventories thank to databases.
Interpretations had to be performed all along these steps.
Let’s now focus on the third main step of the LCA : the impact assessment. This step
is crucial since no assessment means an implicit assessment !
An example from the automobile industry - and adressed in lesson 5 - will be detailled
to illustrate the theory developped in this lesson. We will compare three kind of frontend panel made of either steel or aluminium or composite material.
1.3 The front-end panel
Function: transport over the whole car lifecycle (200'000 km).
Functional unit: 1 component of equivalent
stiffness for a given service of 200'000 km.
System boundaries: the whole life cycle
from extraction of raw materials to
recycling.
In fra s tru c tu re ,
in p u ts ,tra n s p o rts
R e so u rce s
E n e rg y
e x tra c tio n &
p re p a ra tio n ,
m a tiè re s
p re m iè re s
M a n u fa c tu rin g
R e c y c lin g
U se
W a s te
tre a tm e n t
E m issio n s to a ir, w a te r, so il
S yste m b o u n d a rie s
1.4 Interpreting the raw inventory
Substance
Unité
Final weight
kg
Materials
weights
kg
Manufacturing
Electricity
kWh
Oil
kg
Use phase
Gasoline*
l
Recycling
rate
%
Steel
10 kg
Composite SMC Aluminium
7 kg
3.8 kg
15.4
7
5.9
19.7
2.3
4.7
0.56
15.2
1.8
80
56
30.4
0%
0%
0%
Studying and interpreting the
inventory flows is necessary before
performing any impact assessment.
It avoids many mistakes!
databases
Substance Unit
Weight kg
Resources
Energy MJ
Air
CO2
kg
CO
kg
NOx
kg
SO2
kg
Cd
kg
Pb
kg
Water
Pb
kg
Nitrate
kg
Steel
10 kg
Composite Alu
7 kg
3.8 kg
4287
2865
2686
317
2.6
0.32
0.063
4.0E-6
3.8E-4
222
1.6
0.52
0.173
4.6E-6
2.2E-4
179
0.9
0.23
0.35
4.9E-6
1.4E-4
3.1E-4
1.9E-4
2.0E-5
5.3E-4
1.5E-4
8.2E-4
What can we conclude from this
inventory? Can you determine the best
scenario? Why?
We can't give a definite conclusion
from this inventory. A scenario would
be the best only if all its emissions
were the lowest.
1.5a How to compare pollutants?
Regarding the variety of impacts due to the inventory flows of the different scenarios,
the comparison is not straightforward. It is like comparing apples and pears. And
considering the wide range of pollutants, it can even be seen as putting apples and
elephants side by side...
By the way, can you compare an apple with an elephant?
?

You cannot add an apple and an elephant,
but you can actually compare them.
To enable a comparison, it is necessary to define criterias. For example, for transport,
the comparison has to consider the weight. Thus transporting one elephant is
equivalent to transporting about 20'000 apples.
1.5b Safeguard subjects
In our front-end panel example, as in any LCA example, answering the question of
the best scenario requires to know the impact of each substances on determined
areas. Those areas are defined as the safeguard subjects the society is willing to
protect.
As shown in this diagram, Life Cycle Inventory (LCI) data have to be related to
indicators. Those indicators are representative of effects or damages classified in
different categories.
What would you suggest as safeguard subjects?
Basically, there are four basic areas of protection:
human health, natural environment, natural resources,
man-made environment and life-support systems.
1.6 Life Cycle Inventory Analysis (LCIA)
in practice
Impact assessment will allow us to aggregate all the inventory data in order to
quantify the environmental load. The SETAC – Society of Environmental Toxicology
And Chemistry – recommends to perform this aggregation in three steps :
– Classification, organization of emissions in categories that represent given kind of
problems . SETAC standards define fifteen areas to protect:
Input related categories:
abiotic resources;
biotic resources;
land;
erosion.
Output related categories:
global warming;
acidification;
depletion ozone layer;
eutrophication;
human toxicology;
ecotoxicology;
photo oxidant formation; casualties.
noise;
odours;
radiation;
– Characterization, application of specific weighting factors to emissions in order to
have a unique unit within each impact category (e.g. kgPb for human toxicity, …),
– Normalisation + weighting, application of other weighting factors to these impact
classes in order to gather them into damage classes or a single score.
1.7 Structure of impact assessment Ecoindicator99
Inventory Classification
CO2
crude oil
Characterisation and Normalisation
Carcinogenicity
Respiratory organic pollution
Respiratory inorganic pollution
Radiation
Ozone layer depletion
Climate change
Weighting
Human health
NOX
iron (ore)
phosphates
Ecotoxicity
Acidification, eutrophication
Land use
Ecosystem
quality
Minerals
Fossil fuels
Ressources
Indicators (pt)
2.1a Classification - Definition
During the former steps of LCA, the systems have been properly defined and their
boundaries carefully set. This has allowed to get the inventory of the emissions and
extractions that cross these boundaries. We are now facing a huge list of data…
How do you react in front of this new challenge ?
The Classification step allows to dispatch the pollutants according to the area of
protection they affect (ex: CO2, CH4 and N2O influence the Global warming). This
step is required to carry on the LCA process.
2.1b Classification - Ecoindicator99
Inventory Classification
CO2
crude oil
Characterisation and Normalisation
Carcinogenicity
Respiratory organic pollution
Respiratory inorganic pollution
Radiation
Ozone layer depletion
Climate change
Weighting
Human health
NOX
iron (ore)
phosphates
Ecotoxicity
Acidification, eutrophication
Land use
Ecosystem
quality
Minerals
Fossil fuels
Ressources
Indicators (pt)
2.2a Characterisation - Definition
Once the Classification is achieved,
the problem is to find a common unit
to aggregate the different emissions
and perform comparisons. What is
required is a category indicator
representative of the considered area
of protection. For example, a common
indicator chosen for Global warming is
the equivalent kg of CO2.
Quantitative modelling enables to get the weighting factor that links each pollutant to
the category indicator. Coming back to the Global warming example:
IPCC*
Ecoindicator
Pollutant weighting factor weighting factor
(kg CO2/kg)
(DALY/kg)
CO2
1
2.1*10-7
CH4
6.5
4.1*10-6
N2O
170
6.9*10-5
*IPCC: International Panel on Climate Change (International organism)
2.2b Characterisation - Definition
Next two slides present the characterisation step for our front-end panel example
with ecoindicator99. The categories and their indicators are listed in the table below.
Category
Carcinogenicity
Respiratory organic pollution
Respiratory inorganic pollution
Radiation
Ozone layer depletion
Climate change
Ecotoxicity
Indicator - unit
DALY
DALY
DALY
DALY
DALY
DALY
Acidification, eutrophication
PDF*m *year
Land use
Minerals
Fossil fuels
PDF*m *year
MJsurplus
MJsurplus
2
For supplementary information on
Ecoindicator99:
http://www.pre.nl/eco-indicator99
PDF*m *year
2
2
DALY or "disability adjusted life years": the total amount of healthy life lost, to all
causes, whether from premature mortality or from some degree of disability during a
period of time.
PDF*m2*years or "potentially of disappeared fraction": the percentage of species
disappeared in a certain area due to the environmental load.
MJsurplus: the energy requirements in mining and concentrating of ores with
decreasing material content, based on present known technology.
2.2c Characterisation - Ecoindicator99
Inventory Classification
CO2
crude oil
Characterisation and Normalisation
Carcinogenicity
Respiratory organic pollution
Respiratory inorganic pollution
Radiation
Ozone layer depletion
Climate change
Weighting
Human health
NOX
iron (ore)
phosphates
Ecotoxicity
Acidification, eutrophication
Land use
Ecosystem
quality
Minerals
Fossil fuels
Ressources
Indicators (pt)
2.2d Characterisation - Ecoindicator99
140
Percentage (%)
Steel
Aluminium
120
Recycled Aluminium
SMC
100
80
60
40
20
0
Carcinogenicity
Resp.
Organics
Resp.
Inorganics
Climate
change
Ecotoxicity
Acid.
Eutroph.
2.2e Characterisation - Interpretation
Which scenario turns out to be the best ?
The recycled aluminium front-end panel is the best as it has the lowest scores in all
impact categories.
It is not possible to determine the worst scenario at this point, as none of them has
the highest impacts in all categories.
Further assessment is required…
Indeed, at that stage, we can not compare the different impact classes with each
other since they are not expressed in consistent units.
To help to overcome this problem, we will begin with a normalisation step which
answers the following question:
Does our scenario induce an important effect compared to the overall worldwide
effect ?
2.3a Normalisation - Definition
At this point, the idea is to analyse the respective share of each impact in the overall
worldwide effect. This comparison between the scenarios’ and the average European
impacts enables to evaluate the relative importance of the former. It does not give a
damage oriented comparison but a better intuition of the impact of the scenarios.
Normalisation enables you to see the relative contribution from the material
production to each already existing effect.
Next two slides come back to the front-end panel example to illustrate normalisation
with Ecoindicator99.
2.3b Normalisation - Ecoindicator99
Inventory Classification
CO2
crude oil
Characterisation and Normalisation
Carcinogenicity
Respiratory organic pollution
Respiratory inorganic pollution
Radiation
Ozone layer depletion
Climate change
Weighting
Human health
NOX
iron (ore)
phosphates
Ecotoxicity
Acidification, eutrophication
Land use
Ecosystem
quality
Minerals
Fossil fuels
Ressources
Indicators (pt)
2.3c Normalisation - Ecoindicator99
0.025
Steel
person.year/FU
Aluminium
0.02
Recycled Aluminium
SMC
0.015
0.01
0.005
0
Carcinogenicity
Resp.
Organics
Resp.
Inorganics
Climate
change
Ecotoxicity
Acid.
Eutroph.
2.3d Normalisation - Interpretation
Which scenario turns out to be the best?
The recycled aluminium front-end panel is the best as it has the lowest scores in all
impact categories.
It is not possible to determine the worst scenario at this point.
On which impact categories do the scenarios have the greatest effects?
For all scenarios, the impact on climate change, and to a lower extent, the impact
caused by inorganic substances on respiration, are the most important.
Why cannot we determine a worst scenario? What is requested?
None of them shows the highest damages in all categories…
Further assessment is required…
Indeed, at that level, the different impact categories can be compared with each other
since they are in the same unit. Nevertheless, no final judgment can be made as
effects are not considered to be of equal importance. A further step, the Weighting, is
necessary.
2.4a Weighting - Definition
The question we have to ask ourselves now is : « How to value these social
weighting factors ? »
Three main assessment methods are currently used to value these factors :
–Monetary methods (willingness to pay): here, the impacts are transformed into
costs, the central point is how much money we are ready to pay to avoid an impact.
One year of life lost is estimated to 300’000 €
(dixit european insurance companies).
–Consensual methods involving expert panels or stakeholders, who gather to
determine the relative importance of the different safeguard subjects.
Global warming is currently considered as a
hotter topic than eutrophication.
–Distance to target methods: the normalisation results are compared with political
objectives.
In Southern countries, Human Health has a
higher priority than Ecosystem Quality.
Next slides show the situation of Weighting in the LCA process and its application to
our front-end panel example.
2.4b Weighting - Ecoindicator99
Inventory Classification
CO2
crude oil
Characterisation and Normalisation
Carcinogenicity
Respiratory organic pollution
Respiratory inorganic pollution
Radiation
Ozone layer depletion
Climate change
Weighting
Human health
NOX
iron (ore)
phosphates
Ecotoxicity
Acidification, eutrophication
Land use
Ecosystem
quality
Minerals
Fossil fuels
Ressources
Indicators (pt)
2.4c Weighting - Ecoindicator99
Points
Acid. Eutroph.
Ecotoxicity
10
Climate change
Resp. Inorganics
8
Resp. Organics
Carcinogenicity
6
4
2
0
Steel
Aluminium
Recycled Aluminium
SMC
2.4d Weighting - Definition
Ecoindicator 99 performs an evaluation based on a consensual method.
Which scenario turns out to be the best ? (running gag…)
Previous slide confirms that recycled aluminium turns out to be the best
scenario. Moreover, we can now establish a ranking between our studied
scenarios. The steel front-end panel is the worst, SMC and aluminium
are more environmentally friendly, recycled aluminium is the best.
3. Questions of understanding
–Why isn't it possible to determine the best scenario just after LCI?
– What do you have to define if you want to compare a bicycle
with a pair of jeans, for example?
– What are the different steps of LCIA? Give a short description of
them.
– How can you value social Weighting factors?