Page 193 - Design for Environment A Guide to Sustainable Product Development

172 Cha pte r Ni ne

Scoring and indexing schemes are particularly useful for captur-
ing complex outcomes, such as ecological impacts, in cases where the
absence of adequate data and validated models makes quantitative
assessment impossible. However, by providing a mechanistic, repeat-
able algorithm, scoring methods can lead to false confidence in results
that are at best approximate and occasionally outright wrong. It can
be argued that such methods encourage “environmental illiteracy”
on the part of design teams. For example, without delving into the
logic of the system, it may be difficult for designers to understand
what technical changes might result in an improved score.
Example: An early example of a qualitative DFE matrix was adopted by AT&T
for material selection [3]. The approach arrays alternative technologies (rows)
against life-cycle stages (columns) and indicates both the magnitude and
uncertainty of the impact in each cell of the matrix through graphic icons.
Without requiring detailed data or laborious calculations, this approach offers
useful insights into the environmental preferability of different technologies.
For example, the matrix was used to assess three alternatives to lead solder in
electronic devices—indium alloys, bismuth alloys, and conductive epoxies. The
results suggested that, from a life-cycle perspective, lead is preferable to the
alternatives because the latter tend to utilize more resources and generate more
emissions in the extraction and processing stages.
Example: A more recent example is a rating system developed by the Green
Electronics Council (GEC) to help consumers choose products with envi -
ronmentally preferable designs. The EPEAT (Electronic Product Environmental
Assessment Tool) evaluates products on 51 environmental criteria in eight
categories, including materials use, design for end of life, and packaging. GEC
estimates that 2007 purchases of EPEAT-certified products have reduced the
use of primary materials by 75.5 million metric tons (equivalent to the weight
of more than 585 million refrigerators) and reduced the use of toxic materials,
including mercury, by 3,220 metric tons (equivalent to the weight of 1.6 million
bricks). In addition, the electricity savings are 42.2 billion kilowatt-hours—
enough to power 3.7 million U.S. homes for a year.

Environmental Analysis
Not surprisingly, environmental analysis methods play an essential
role in DFE. The purpose of these methods is to help designers
understand the implications of alternative design choices in terms
of their expected effects on ecological resources. However, ecological
systems are complex, dynamic, and not well understood, so the
available methods have inherent limitations. While these methods
are based on scientific assumptions, they are generally impossible
to validate, so the conclusions should be used with caution. This
section focuses on the two most commonly used categories of meth-
ods—footprint indicators and life-cycle assessment. There is some
overlap in that the calculation of an environmental footprint over
the full product life cycle necessarily involves the use of basic life-
cycle assessment methods.