Evaluate product systems
This section describes the final steps to calculate the product
systems' emissions and display the results.
Define a Product System Completely
To evaluate a product system (i.e. calculate the emissions) it must
first be completely defined. This means
- each reference flow is
connected to a utilization
process. Utilization processes that are not connected to a reference flow will not be
considered in the calculation.
- all utilization processes
are edited according to your specifications./li>
- you have entered the correct correct amount of kilometers into
the reference flows, that shall
be traveled with the respective vehicles. This is important to
build and compare mobility chains.
Calculate emissions
When the product system(s) are completely defined you may start the
calculation of emissions. This is done by clicking one of the
"evaluate" buttons (
) which can be found in any of the graphics panels. After a short while the
results will be displayed graphically in each
open graphics panel.
When you click the "evaluate" button, the program will
consider all product systems which have an open product system editor, i.e. those
that have a tab atop the editor area. Each product system is
considered as a unit, i.e. one particular journey. This allows to
compare mobility chains:
Example (Screenshot): Product system 1 (PS1) shows the case
where a trip of 15 km is traveled using a diesel powered car. This is
achieved by connecting the utilization process "Car (diesel)"
to a reference flow and setting the value field to "15.0".
In product system 2 (PS2) the same distance is traveled first by using
the bike for 3 km and the rest (12 km) by taking the tramway. Here,
the utilization processes for bicycle and tramway have to be connected
each to a reference flow and then entering "3.0" and
"12.0" in the respective number fields of the reference flows.
The graphics will then show all emissions from
PS1 besides those of PS2.
The sum of the kilometers entered in the reference flows has to be
the same in all evaluated product systems. Otherwise a comparison
of emissions would not make sense.
Display of results
ECOCLASS shows emissions in three aggregated categories:
- CO2 Equivalents (greenhouse effect): This is an
aggregate of all emissions that contribute to the anthropogenic
greenhouse effect and thereby to climate change, mainly carbon
dioxide, methane, laughing gas and halo-carbons. To make these emissions
comparable we calculate from their amount and their global warming
potentials the amount of CO2 which would yield the same contribution
to the greenhouse effect. These "CO2 equivalents" are
added and displayed.
- SO2 Equivalents ("acid rain"): This is an
aggregate of all emissions that contribute to the release of
(sulphuric) acid and thereby to acid rain, mainly sulphur dioxide,
nitrous oxides, and ammonia. To make these emissions
comparable we calculate from their amount and their acidification
potentials the amount of SO2 which would yield the same contribution
to acid rain. These "SO2 equivalents" are
added and displayed.
- TOPP Equivalents (summer's smog): This is an
aggregate of all emissions that have a potential to form precursors
of tropospheric ozone, mainly organic compounds, nitrous oxides and
carbon monoxide. Tropospheric ozone is the main reason for summer's
smog formation. The potential of ozone formation is calculated from
the amount and the respective ozone formation rates. The greater
the amount of ozone precursor substances (Tropospheric Ozone Precursor
Potential, TOPP), the greater the probability of summer's smog.
The internal calculation treats each gas separately, the aggregation
is done in the very last step. Aggregation is necessary to keep the
graphics clear while still showing the most important impact categories.
Bar chart
The bar chart shows absolute emissions of CO2 equivalents, SO2
equivalents, and TOPP equivalents for each product system. The
emissions that accrue in the "upstream processes"
(i.e. during the production of the vehicle and the fuel) are displayed
in shaded grey. For the vehicle we
consider only the share of production emissions that corresponds to
the share of journey distance to the expected lifetime of the vehicle.
The difference between upstream and total emissions yield the
emissions during the utilization. For electricity powered vehicles,
however, the emissions accruing during electricity generation are
always considered to be upstream, so these have no direct
emissions.

Star chart
The star chart has three axes to indicate the total emissions of
each product system in the three emissions categories (i.e. no
separation between upstream and direct emissions). For each emissions
category, the maximum value from all product systems is set to 1
(=100%) and the values from the other product systems are shown
relative to this maximum value. The values of each product system are
assigned the same color.
This kind of graph makes relative differences between product
systems explicit. For example, one sees very quickly if one product
system has less emissions in all categories than another, and how
large the relative differences are.
