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The standardized calculation model proposed by Wackernagel and Rees (1998) is referred to
as a macro, compound-based, or top-down approach, which uses global-scale data
(international level), and describes the final consumption for a given land use category
(agriculture, fisheries). A new approach was developed a few years after the creation of the
EF. The latter quantifies material and energy flows consumed by human activities (Barrett et
al., 2002). This approach supports socio-economic and environmental policies based on locally
produced statistics and allows for a bottom-up analysis (Monfatt et al., 2005). Simmons and
Chambers first reported this methodology in an article describing the EcoCal software
(Simmon & Chambers, 1998).
The component-based approach calculates the EF of all significant components of a
population's resource use and waste generation (Simmon et al., 2000; Monfreda et al., 2004).
This method is ideally used at the city scale, accurately capturing resource consumption.
Indeed, bottom-up methods are based on life cycle assessment (LCA) studies for considered
products and processes. The LCA's outputs are then converted into overall conversion figures,
allowing for highly detailed LCA inventories and a more accurate description of the products
consumed (Sala et al., 2020).
In the component-based EF, the calculation starts with identifying each component based on
locally relevant data. This model enables a detailed assessment of the city's metabolism,
integrating material and energy flow budgets (urban metabolism) into the LCA (Simmon et al.,
2000; Monfatt et al., 2005; Moore, 2013). Therefore, the final result's accuracy is driven by
the exhaustiveness of the components’ inventory and the reliability of LCA’s outputs
(Monfreda et al., 2004). Finally, for a given population and a defined period, the componentbased EF provides an estimate of human demand on each of the land types previously
described in the original Wackernagel method: cropland, grazing land, forest, built-up land,
and fishing grounds, as well as energy land (carbon sequestration land). Indeed, this approach
maintains the central structure while focusing on the small-scale activity instead of aggregated
consumption (Barrett, 2001). Both methods are complementary. Indeed, the top-down
(original) method covers all final consumption categories, providing a broad scope of all
activities (national fisheries production's consumption), and the bottom-up method delivers
more details and allows to target a category of consumption (energy consumption during
fishing).
Considering the scale, the component approach requires large input data sets. Therefore, the
calculation method adopted in this work integrates urban metabolism analysis as a
preliminary step and a data generator tool for the EF estimate. Indeed, the study will first
present an inventory of three main components, namely biological resources (Material),
energy consumption (Energy), and associated infrastructures (Built land).
1.5.2. Integrated analysis
The bottom-up model requires specific inputs. The data describing the previously described
component are obtained through an analysis of urban metabolism and life cycle of each
activity.
The standardized calculation model proposed by Wackernagel and Rees (1998) is referred to
as a macro, compound-based, or top-down approach, which uses global-scale data
(international level), and describes the final consumption for a given land use category
(agriculture, fisheries). A new approach was developed a few years after the creation of the
EF. The latter quantifies material and energy flows consumed by human activities (Barrett et
al., 2002). This approach supports socio-economic and environmental policies based on locally
produced statistics and allows for a bottom-up analysis (Monfatt et al., 2005). Simmons and
Chambers first reported this methodology in an article describing the EcoCal software
(Simmon & Chambers, 1998).
The component-based approach calculates the EF of all significant components of a
population's resource use and waste generation (Simmon et al., 2000; Monfreda et al., 2004).
This method is ideally used at the city scale, accurately capturing resource consumption.
Indeed, bottom-up methods are based on life cycle assessment (LCA) studies for considered
products and processes. The LCA's outputs are then converted into overall conversion figures,
allowing for highly detailed LCA inventories and a more accurate description of the products
consumed (Sala et al., 2020).
In the component-based EF, the calculation starts with identifying each component based on
locally relevant data. This model enables a detailed assessment of the city's metabolism,
integrating material and energy flow budgets (urban metabolism) into the LCA (Simmon et al.,
2000; Monfatt et al., 2005; Moore, 2013). Therefore, the final result's accuracy is driven by
the exhaustiveness of the components’ inventory and the reliability of LCA’s outputs
(Monfreda et al., 2004). Finally, for a given population and a defined period, the componentbased EF provides an estimate of human demand on each of the land types previously
described in the original Wackernagel method: cropland, grazing land, forest, built-up land,
and fishing grounds, as well as energy land (carbon sequestration land). Indeed, this approach
maintains the central structure while focusing on the small-scale activity instead of aggregated
consumption (Barrett, 2001). Both methods are complementary. Indeed, the top-down
(original) method covers all final consumption categories, providing a broad scope of all
activities (national fisheries production's consumption), and the bottom-up method delivers
more details and allows to target a category of consumption (energy consumption during
fishing).
Considering the scale, the component approach requires large input data sets. Therefore, the
calculation method adopted in this work integrates urban metabolism analysis as a
preliminary step and a data generator tool for the EF estimate. Indeed, the study will first
present an inventory of three main components, namely biological resources (Material),
energy consumption (Energy), and associated infrastructures (Built land).
1.5.2. Integrated analysis
The bottom-up model requires specific inputs. The data describing the previously described
component are obtained through an analysis of urban metabolism and life cycle of each
activity.