10
F. Scrucca et al.
The application of CF standards could be more viable for companies, due to the
lower specific methodological requirements.
4 The Influence of Methodological Choices on CF Results
Despite CF is a standardized methodology, different methodological choices can
lead to a difficult comparison of the results. In this paragraph the main critical issues
in defining the CF model are discussed. Harmonization initiatives should be evaluated to enhance the comparability of CF case studies through the use of consistent
methodological choices.
4.1 Selection of Functional Unit
Definition of the functional unit is a key aspect in a CF study because it allows to
compare the results of different but functionally equivalent systems.
The existing CF methodologies provide similar guidance for the selection of the
functional unit, but none of them suggest functional units for specific products. For
example, ISO/TS 14067 suggests “Where relevant PCR or CFP-PCR exist, they shall
be adopted” and “If CFP-PCR are adopted for the CFP study, the quantification shall
be conducted according to the requirements in these CFP-PCR”.
The influence of the choice of functional unit on CF results has been highlighted
in different sectors, such as food, biorefinery, and building materials.
In the food sector, Notarnicola et al. [55] point out that yield or area are the
most used functional units, even if neither takes into account the true function of
the products. At this regard, they highlight that more accurate choices could be
based on the nutritional or the hedonistic value of the food. Saarinen et al. [71]
suggested that, despite the nutrient content of food could reflect food function better,
it is not possible to evaluate food CF based on individual nutrients (carbohydrate,
protein, vitamins, and minerals) because CF/individual nutrient vary greatly and
randomly. Therefore, recently different nutrient density models have been developed
and applied to compare CFs of food products [48, 86]. In particular, Sonesson et al.
[77] adopted a functional unit which reflected the nutrient content of each food in
relation to the nutritional supply of the diet, in order to consider the nutrient quality
in a given dietary context.
Another interesting option could be the one suggested by van der Werf and Salou
[82] which is based on the economic value of the product,in this way the product
quality is considered in the product price. They found that a mass-based functional
unit favors systems that focus on quantity rather than quality while an economic-value
based functional unit favors systems producing food products of greater quality.
The difficulties in the selection of the appropriate functional unit in the CF studies
of biorefineries are due to their multifunctional nature. Ahlgren et al. [1] identified
F. Scrucca et al.
The application of CF standards could be more viable for companies, due to the
lower specific methodological requirements.
4 The Influence of Methodological Choices on CF Results
Despite CF is a standardized methodology, different methodological choices can
lead to a difficult comparison of the results. In this paragraph the main critical issues
in defining the CF model are discussed. Harmonization initiatives should be evaluated to enhance the comparability of CF case studies through the use of consistent
methodological choices.
4.1 Selection of Functional Unit
Definition of the functional unit is a key aspect in a CF study because it allows to
compare the results of different but functionally equivalent systems.
The existing CF methodologies provide similar guidance for the selection of the
functional unit, but none of them suggest functional units for specific products. For
example, ISO/TS 14067 suggests “Where relevant PCR or CFP-PCR exist, they shall
be adopted” and “If CFP-PCR are adopted for the CFP study, the quantification shall
be conducted according to the requirements in these CFP-PCR”.
The influence of the choice of functional unit on CF results has been highlighted
in different sectors, such as food, biorefinery, and building materials.
In the food sector, Notarnicola et al. [55] point out that yield or area are the
most used functional units, even if neither takes into account the true function of
the products. At this regard, they highlight that more accurate choices could be
based on the nutritional or the hedonistic value of the food. Saarinen et al. [71]
suggested that, despite the nutrient content of food could reflect food function better,
it is not possible to evaluate food CF based on individual nutrients (carbohydrate,
protein, vitamins, and minerals) because CF/individual nutrient vary greatly and
randomly. Therefore, recently different nutrient density models have been developed
and applied to compare CFs of food products [48, 86]. In particular, Sonesson et al.
[77] adopted a functional unit which reflected the nutrient content of each food in
relation to the nutritional supply of the diet, in order to consider the nutrient quality
in a given dietary context.
Another interesting option could be the one suggested by van der Werf and Salou
[82] which is based on the economic value of the product,in this way the product
quality is considered in the product price. They found that a mass-based functional
unit favors systems that focus on quantity rather than quality while an economic-value
based functional unit favors systems producing food products of greater quality.
The difficulties in the selection of the appropriate functional unit in the CF studies
of biorefineries are due to their multifunctional nature. Ahlgren et al. [1] identified