Page 139 - Design for Environment A Guide to Sustainable Product Development

118 Cha pte r Ei g h t

1. Prescriptive guidelines are definite statements about what
designers should or should not do, and are sometimes called
design rules. There are many such guidelines related to envi-
ronmental health and safety—for example, lists of banned
materials.
2. Suggestive guidelines represent accumulated knowledge,
including best practices and lessons learned, but they are not
strict rules. They merely point in useful directions, or con-
versely, indicate characteristics that should be avoided.

Virtually all of the DFE guidelines presented here are suggestive.
There are several reasons for this—DFE is continually evolving, DFE
is mainly a voluntary, nonregulated practice, and DFE involves many
complex trade-offs so that general rules are difficult to find. Individ-
ual companies typically establish design rules that are appropriate
for their products. There are a number of benefits from using guide-
lines, whether for DFE or any other DFX discipline:
• They encourage consistency among different development
teams in areas where consistency is desirable or necessary,
e.g., standard material labeling schemes.
• They promote continuity through the accumulation of knowl-
edge (“lore”) over successive design cycles and allow that
knowledge to be preserved and passed down.
• They lead to a more systematic design process that is less
dependent upon the idiosyncrasies or particular biases of indi-
vidual designers.
• They expand the scope of issues considered during design,
allowing the team to anticipate downstream pitfalls or con-
straints that they may have ignored.

Despite these benefits, in a fast-paced product development envi-
ronment it is often difficult to ensure that product teams pay atten-
tion to guidelines, especially if they are only suggestive and not
strict requirements. Various approaches are used to make developers
aware of such guidelines, ranging from printed guidance manuals to
online decision aids. To the extent that such tools can be built into a
“stage-gate” development process, they can be extremely effective in
influencing product designs. A classic example of successful intro-
duction of DFX guidelines is the Design for Manufacture and Assem-
bly (DFMA) methodology, originally developed by Boothroyd and
Dewhurst at the University of Rhode Island. This methodology has
been encoded into software tools that are routinely used by major
companies to simplify designs and, hence, reduce their assembly costs.
Design automation companies such as AutoDesk are currently devel-
oping decision support tools that can play an analogous role for DFE.