Page 171 - Materials Chemistry, Second Edition

156 A. Bjørn et al.

impacts, then its sensitivity and uncertainty data should generally not be a high
priority as illustrated by Fig. 12.3.
For the background system, many LCI databases include uncertainty information
on processes, which can feed into uncertainty and sensitivity analysis in LCA
software. The practitioner therefore needs not to bother about such data in the
inventory analysis.

9.7 Reporting

The reporting of the inventory analysis should contain six elements:
1. Documentation of LCI model at system level.
2. Documentation of each unit process.
3. Documentation of metadata.
4. Documentation of LCI results.
5. Assumptions for each life cycle stage.
6. Documentation of data collected for uncertainty and sensitivity analysis.
Elements 1, 2 and 3 should allow the reader to recreate the LCI results, which are
documented in Element 4 (i.e. exigence of reproducibility of the study). Element 5
should allow the reader to judge the reasonability of all assumptions performed (i.e.
exigence of transparency) and Element 6 should allow the reader to recreate the
uncertainty and sensitivity analysis (exigence of reproducibility and consistency).
Below we elaborate on each element and we further refer to the illustrative case on
window frames in Chap. 39 for an example of how the inventory analysis may be
reported.

9.7.1 Documentation of LCI Model at System Level

We propose to use a flowchart that contains all the linked processes in the fore-
ground system for each studied product system and shows their links to processes in
the background system. Each process should be named and, depending on the size
of the foreground system, flow names and quantities may also be given (this
information is, however, not essential, as it will also be given in second reporting
element). Figure 9.10 illustrates how to document a flow chart for a simple,
hypothetical LCI model (flow names and quantities not shown). Flow chart should
be reported in the main part of an LCA report.
Note that only the unit processes of the background system that are linked to
(‘neighbouring’) the foreground system needs to be included in the flow chart.
These are processes UP1 to UP8 in Fig. 9.10. From this information, the reader