Page 148 - Design for Environment A Guide to Sustainable Product Development

Design Rules and Guidelines 127

• Reduce end-use power consumption—Laptop computers
and many other electrical or electronic devices have power
management features that power down a unit when it has not
been used for some length of time. In other types of products,
such as refrigerators, energy is conserved through develop-
ing more efficient motors and reducing the energy load. The
U.S. government has helped to promote energy efficiency
of electronic devices and procurement of “environmentally
preferable” products (see Chapter 3).
• Reduce end-use material consumption—Products requiring
maintenance materials or replacement parts, such as ink car-
tridges and batteries, can consume significant resources over
their lifetime. In many cases, the end-use environmental foot-
print of a durable product far outweighs the energy and
materials required to produce it. Design efforts that reduce or
eliminate these requirements will not only benefit the envi-
ronment, but also will increase convenience and reduce “cost
of ownership” for the customer.
Example: Kyocera introduced a new printer design which eliminates
the need for a disposable or recyclable toner cartridge. The printer
uses a self-cleaning printing drum coated with superhard amorphous
silicon. With this more elegant design, users need only add toner to
maintain the device.
Recycled Material Specification
An important aspect of sustainable development is the conservation
of nonrenewable re sources. Manufacturing firms have long been in
the habit of specifying virgin materials that are well-characterized
because they were manufactured through a precise process with
known feedstocks. Driven by growing environmental awareness,
both government and industry organizations have begun to specify
more “environmentally conscious” materials that have significant
levels (25% to 100%) of recycled content. This is feasible to the extent
that substitution of recycled materials with potential impurities is
cost-effective and does not compromise the quality of the final prod-
uct. For example, metals are easily recycled, because they can be
purified in a molten state. Likewise, paper, glass, and many other
materials can achieve substantial levels of recycled content.
However, the situation is different with engineering thermoplas-
tics. The cost of separating the individual components is high, and
the thermo-mechanical properties associated with recycled resins
developed from mixed waste can be significantly compromised. One
approach is to utilize virgin materials only for critical components,
and recycled materials for less demanding applications such as base
assemblies. Resin manufacturers have begun adding compatibilizing
agents to strengthen both the physical and chemical bonds among