4. It should be noted that the LCIA results could hence be used
as the basis for a sensitivity analysis to identify the main contributing elementary flows and processes in algal fuels production. This could serve as a means of improving the inventory
data [51]. This may also encompass the use of normalization
and weighting in LCA of algal fuels production/use chain, if it
has been decided to implement the cut-off criteria in relationship to the normalized and weighted LCIA results [29].
6.2 Normalization
Normalization is an optional step which could be performed to
obtain dimensionless, normalized LCIA results. To do so, the
LCIA results can be multiplied by normalization factors representing the overall inventory of a reference such as the whole country or
an average citizen [52]. Normalized LCIA results are given for each
impact topic on midpoint level (such as climate change, eutrophication, etc.) or for area of protection on endpoint level (such as
human health, ecosystem quality, and resources) [53]. When displaying the normalized LCIA results of the different impact topics
next to each other, the level of contribution of different impact
topics to the analyzed system could be realized.
1. Normalize the results of LCIA of algal fuels for two purposes [51]:
(a) Application of normalization to support interpretation: In
support of the interpretation of the results of algal fuels,
normalization is an optional step under ISO.
(b) Application of normalization in cut-off quantification: For
quantification of the achieved completeness/cut-off, a
common reference could be used as the normalization
basis and the results of different impact categories may
be normalized through expressing them relative to that
reference.
2. It should be noted that normalized results of algal fuels shall not
be summed up directly across different impact categories as this
would suggest an even weighting of all impact categories
[29]. This is in fact the case unless even weighting is intended
and clearly identified as weighting when reporting the results [29].
6.3 Weighting
Weighting is also an optional step through which normalized LCIA
results of algal fuels could be multiplied by a set of weighting
factors. This would result in weighted LCIA results for midpoint
and endpoint categories which could be finally summed up to
obtain a single-value for all impact categories [54].
1. It should be noted that a weighting set always involves value
choices.
2. Weight the results of LCIA of algal fuels for two purposes:
(a) Application of weighting to support interpretation: In
support of the interpretation of the results of algal fuels
chain as an additional, optional element, “weighting” of
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Homa Hosseinzadeh-Bandbafha et al.
as the basis for a sensitivity analysis to identify the main contributing elementary flows and processes in algal fuels production. This could serve as a means of improving the inventory
data [51]. This may also encompass the use of normalization
and weighting in LCA of algal fuels production/use chain, if it
has been decided to implement the cut-off criteria in relationship to the normalized and weighted LCIA results [29].
6.2 Normalization
Normalization is an optional step which could be performed to
obtain dimensionless, normalized LCIA results. To do so, the
LCIA results can be multiplied by normalization factors representing the overall inventory of a reference such as the whole country or
an average citizen [52]. Normalized LCIA results are given for each
impact topic on midpoint level (such as climate change, eutrophication, etc.) or for area of protection on endpoint level (such as
human health, ecosystem quality, and resources) [53]. When displaying the normalized LCIA results of the different impact topics
next to each other, the level of contribution of different impact
topics to the analyzed system could be realized.
1. Normalize the results of LCIA of algal fuels for two purposes [51]:
(a) Application of normalization to support interpretation: In
support of the interpretation of the results of algal fuels,
normalization is an optional step under ISO.
(b) Application of normalization in cut-off quantification: For
quantification of the achieved completeness/cut-off, a
common reference could be used as the normalization
basis and the results of different impact categories may
be normalized through expressing them relative to that
reference.
2. It should be noted that normalized results of algal fuels shall not
be summed up directly across different impact categories as this
would suggest an even weighting of all impact categories
[29]. This is in fact the case unless even weighting is intended
and clearly identified as weighting when reporting the results [29].
6.3 Weighting
Weighting is also an optional step through which normalized LCIA
results of algal fuels could be multiplied by a set of weighting
factors. This would result in weighted LCIA results for midpoint
and endpoint categories which could be finally summed up to
obtain a single-value for all impact categories [54].
1. It should be noted that a weighting set always involves value
choices.
2. Weight the results of LCIA of algal fuels for two purposes:
(a) Application of weighting to support interpretation: In
support of the interpretation of the results of algal fuels
chain as an additional, optional element, “weighting” of
138
Homa Hosseinzadeh-Bandbafha et al.