Functionality
The functionality expresses the cause-effect relationship (or model) between the
input and the output, e.g. considering how transport demand of goods and people
translates into kilometres driven and/or fuels used in different types of vehicles.
While for some “base” period (often a past year for which a fairly complete set of
data exists) an inventory is often adequate to attain directly the output of the
DRIVERS block (e.g. transport kilometres driven or fuel used), for projections into
the future the input-functionality-output chain needs to respond to the assumed
future changes in economic activities, technology developments, etc. This chain can
be implemented at different levels of complexity, from simple calculation of
cause-effect relationships to detailed traffic, housing and energy system models.
City or regional level assessments can be implemented using local information
(bottom-up), or derived from national level models (top-down), or as a combination
of both approaches. Models with dynamic spatial capabilities are desirable to be
able to assess changes in spatial patterns of activities.
In general, for the DRIVERS block implementation, the following three-level
classification can be adopted:
– LEVEL 1: when a top-down approach is applied, using coarse spatial and
temporal allocation schemes;
– LEVEL 2: when a bottom-up approach with generic (i.e. national/aggregated)
assumptions is applied, using realistic spatial and temporal allocation schemes;
– LEVEL 3: when a bottom-up approach with specific (i.e. local/detailed)
assumptions is applied, using local spatial and temporal allocation schemes.
In the following sections, a more detailed description of the DRIVERS block
implementation will be provided, focusing on two important aspects of DRIVERS,
that is to say:
– Base year inventory and projections;
– Spatial and temporal assessment.
Base Year Inventory and Projections
The inventory of activities and emission-wise relevant technologies can be based on
the data collected or modelled from the respective city area or region (bottom-up
approach), or on statistics of a wider area (typically a country) of which the share of
the respective city area or region is defined using weighting surrogates (top-down
approach).
In some cases it might be difficult to attain reliable, representative collected data
from certain areas. For instance, technology stock inventory at sub-national level is
often not practical, and national level data have to be used. In case of a top-down
approach, the reliability of the activity estimate depends on the representativeness
of the weighting surrogates used.
For future projections, it is particularly important that the changes in time of the
input of the DRIVERS block (e.g. changes in population, economical activities,
transport needs etc.) realistically translate into output (i.e. activities and
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N. Blond et al.
The functionality expresses the cause-effect relationship (or model) between the
input and the output, e.g. considering how transport demand of goods and people
translates into kilometres driven and/or fuels used in different types of vehicles.
While for some “base” period (often a past year for which a fairly complete set of
data exists) an inventory is often adequate to attain directly the output of the
DRIVERS block (e.g. transport kilometres driven or fuel used), for projections into
the future the input-functionality-output chain needs to respond to the assumed
future changes in economic activities, technology developments, etc. This chain can
be implemented at different levels of complexity, from simple calculation of
cause-effect relationships to detailed traffic, housing and energy system models.
City or regional level assessments can be implemented using local information
(bottom-up), or derived from national level models (top-down), or as a combination
of both approaches. Models with dynamic spatial capabilities are desirable to be
able to assess changes in spatial patterns of activities.
In general, for the DRIVERS block implementation, the following three-level
classification can be adopted:
– LEVEL 1: when a top-down approach is applied, using coarse spatial and
temporal allocation schemes;
– LEVEL 2: when a bottom-up approach with generic (i.e. national/aggregated)
assumptions is applied, using realistic spatial and temporal allocation schemes;
– LEVEL 3: when a bottom-up approach with specific (i.e. local/detailed)
assumptions is applied, using local spatial and temporal allocation schemes.
In the following sections, a more detailed description of the DRIVERS block
implementation will be provided, focusing on two important aspects of DRIVERS,
that is to say:
– Base year inventory and projections;
– Spatial and temporal assessment.
Base Year Inventory and Projections
The inventory of activities and emission-wise relevant technologies can be based on
the data collected or modelled from the respective city area or region (bottom-up
approach), or on statistics of a wider area (typically a country) of which the share of
the respective city area or region is defined using weighting surrogates (top-down
approach).
In some cases it might be difficult to attain reliable, representative collected data
from certain areas. For instance, technology stock inventory at sub-national level is
often not practical, and national level data have to be used. In case of a top-down
approach, the reliability of the activity estimate depends on the representativeness
of the weighting surrogates used.
For future projections, it is particularly important that the changes in time of the
input of the DRIVERS block (e.g. changes in population, economical activities,
transport needs etc.) realistically translate into output (i.e. activities and
14
N. Blond et al.