Page 150 - Design for Environment A Guide to Sustainable Product Development

Design Rules and Guidelines 129

often with the same level of quality as products manufactured with
brand new components (see Section C.1, Design for Product Re -
covery). Ideally, companies can develop a reverse logistics system
where by spent materials and used components can be recovered,
reprocessed, and recycled back into their supply chain. Establishing a
closed-loop infrastructure provides greater assurance about unifor-
mity, homogeneity, and reliability of the recycled assets. However,
this type of closed-loop recovery is often not feasible, and a preferred
alternative may be to find other companies that can utilize these
material streams as process inputs (see Section C.3, Design for Recy-
clability). A leading practitioner of remanufacturing is Caterpillar, as
described in Chapter 10.

Product Functionality Extension
Products that have multiple uses are by nature eco-efficient, in that
the same amount of material achieves a higher level of functionality.
The greater the proportion of time during a product life that the
product is actually in use, the greater the ratio of value delivered
to resources consumed. There are essentially two types of multiple
functionality: parallel functions, in which the same product is designed
to simultaneously serve several different purposes; and sequential
functions, in which a product is retired from its primary use and then
applied to a secondary and tertiary use (see “Resource Cascading”
below).
Examples of multifunctional products include
• All-in-one copiers that double as printers, scanners, and fax
machines
• Cell phones that also serve as portable music players and per-
sonal digital assistants
• Solvents that are used for metal parts cleaning and then
reused for plant maintenance.

Product Life Extension
Increased product longevity or durability is another strategy to
increase the amount of functionality delivered by a product over
its useful life. This is one of the most direct ways to improve envi -
ronmental performance because it decreases the average life-cycle
resource consumption per product use. There is usually a trade-off
between product cost and longevity, and customers may not be pre-
pared to pay a higher purchase cost for a more durable product.
Moreover, there are some products, notably cell phones and comput-
ers, whose life expectancy (measured in hours of operability or duty
cycles) is much longer than their actual duration of primary use, due
to technological obsolescence.