Page 190 - Design for Environment A Guide to Sustainable Product Development

Analysis Methods for Design Decisions 169

of “yes” does not convey much information. More detailed
performance evaluation would take into account the baseline
waste stream, the types of wastes, the difficulty of recycling,
and the level of improvement achieved.
• Multiple checklists that reflect a large number of guidelines
will often produce conflicts between different attributes of the
design. For example, conflicts may arise between mass and
recyclability (e.g., using polymers versus metals in automo-
tive applications), reusability and energy consumption (e.g.,
refurbishing an old piece of equipment vs. acquiring a new
energy-efficient one), and between toxic chemical use and
energy consumption (e.g., using mercury-containing compact
fluorescent lamps versus incandescent lamps) [1].
• Checklists provide no guidance to product developers regard-
ing the relative importance of different issues or the degree
of effort that is warranted in addressing a specific issue. For
example, is it more important to reduce source volume or to
assure recyclability? Is a 10% reduction in waste a reasonable
goal? How much of the R&D budget should be committed
to achieving these goals? These are challenging questions
that can only be answered through a more rigorous trade-off
analysis.
• Checklists can actually reduce creativity by encouraging a
false sense of complacency. People who have worked through
the checklist in a mechanical fashion may feel that they have
done all that is necessary to consider environmental issues.
Thus, they may fail to become sufficiently involved in DFE
exploration and may overlook important opportunities or
problems that are not covered on the list.
Nevertheless, checklists are an effective starting point for en -
couraging organizations to think about environmental issues and to
begin taking positive actions.

Scoring Matrices
The use of aggregation and scoring techniques for interpreting envi-
ronmental metrics was discussed in Chapter 7. Despite the limita-
tions of these methods, qualitative scoring matrices can be a useful
technique for trade-off analysis in design decisions. They involve
creating a matrix diagram in which the rows represent competing
options or objectives and the columns represent design attributes.
Various indexing and scoring methods can then be applied, based
on available data and/or subjective judgments, to derive categorical
or numerical ratings. The assigned “scores” are seldom physically
meaningful in an absolute sense but can be used to distinguish the