Page 159 - Materials Chemistry, Second Edition

144 A. Bjørn et al.

a waste flow to treatment or as an emission. In many cases, a simple
back-of-the-envelope mass balance calculation will not suffice, because the rela-
tionship between input and output flows is complicated and dependent on many
parameters, and it is more appropriate to apply dedicated LCI models. For example,
the LCI model PestLCI (Birkved and Hauschild 2006) calculates emissions of
pesticides from field applications via different routes (e.g. evaporation, air drift,
emissions through drainage pipes and groundwater leaching) based on the appli-
cation of a specific pesticide to the field, its physical and chemical properties, and a
large number of context-specific parameters, such as crop type, time of application,
soil pH and slope. Note that the data specificity obtained from LCI models can only
be characterised as high if all inputs and parameters are in fact site-specific (and
when relevant, time-specific). If this is not the case, the data specificity is lower.
High and very high specificity data (e.g. on elementary flows such as CO 2
emissions and freshwater use) are sometimes available in reports, e.g. ‘green
accounts’ or CSR reports, published by the company operating the process of
interest, but often the source of such data is employees working with or operating
the process. These may be process engineers monitoring flow data as part of their
daily routine, or they may work in the purchasing department and thereby have
knowledge about the amounts of input flows (materials and energy) purchased and
the identify of suppliers. The latter may be used to contact suppliers for data specific
to processes at their sites and the procedure can, in principle, be repeated several
times to obtain company internal data further upstream in the foreground system.
Company internal data may be accessed by asking the employees to fill out
questionnaires combined with a physical visit to the site, email or telephone contact.
This way of obtaining data can be straightforward or require lots of effort depending
on the willingness of the employees possessing the data to share them in a relevant
format. From our experience, this willingness is generally higher when the com-
missioner of a study is part of the same company and department as the employee
holding the data or if the LCA study has been given attention by the management
level in a company. It should be noted that company internal data are sometimes
confidential. In some cases, they are not possible to obtain, but in other cases the
confidentiality issues may be handled by the LCA practitioner signing a
non-disclosure agreement and reporting any confidential data of importance to the
study in a special appendix to the report that is only accessible to a selected group
of people (typically including members of a peer review panel if the study is peer
reviewed).

9.3.2 Medium and Low Specificity Data

For reasons given above it is in practice rarely feasible (nor necessary) to obtain all
foreground system data from site measurements, i.e. with high or very high