Page 164 - Design for Environment A Guide to Sustainable Product Development

Design Rules and Guidelines 143

Product Simplicity
Design elegance has long been a desirable attribute of products. For
example, during the 1930s, the Bauhaus school of design formalized
its criteria of elegance in terms of minimalism and functional orien-
tation. With the advent of environmental consciousness, elegance
in the form of simplicity has acquired a strong added motivation.
Simplicity usually leads to lower manufacturing cost, lower mate-
rial mass, greater durability, and easier disassembly for purposes
of maintenance or asset recovery. There are several ways in which
designers can try to achieve greater simplicity:

• Reducing the complexity of the product enclosures and
assemblies in terms of their geometric and spatial design, as
well as their functional operation.
• Reducing the number of distinct parts that are incorporated
into a design; this is a well-known technique in the field of
design for manufacture and assembly.
• Designing multifunctional parts that serve a variety of dif-
ferent purposes; e.g., using a single type of fastener for all
assemblies.
• Utilizing common parts in a number of different designs, rep-
resenting either different models in a product family or suc-
cessive product generations.
• Using fewer different types of materials, which tends to lower
costs by facilitating processes associated with procurement,
manufacturing, and disassembly. Designing with fewer mate-
rials both facilitates identification and results in larger
volumes of each material, potentially increasing the sal-
vage value that can be obtained (see Section C.3, Design for
Recyclability).

Disassembly Sequencing
The extent to which a unit, module, assembly, or component should
be disassembled depends not only on the costs of disassembly, sepa-
ration, inspection, sorting, and refurbishment, but also on the reuse,
resale or salvage values. For example, it may not be cost-effective to
disassemble products that contain many different, difficult to identify
materials. Similarly, if components, assemblies and modules cannot
be reused or refurbished, and if they contain largely nonrecyclable
materials, little disassembly is warranted.
The sequence of assembly and the extent to which a product is
disassembled can be represented hierarchically by a disassembly tree, as
shown in Figure 8.7, which identifies all major modules and compo-
nents in the product. There are a sequence of choices in order of prior-
ity to be made at each step in the sequence—reuse as is, refurbish and
resell, disassemble, shred and recycle, or simply dispose of as waste.