Page 65 - Materials Chemistry, Second Edition

LIFE CYCLE INVENTORY MODELING IN PRACTICE 47

an expected range of use applications, it is advisable to structure the analy-
sis so that the products can be compared on single or multiple-unit bases,
depending on use variations.
Example 2. Consumer behavior overrides true functional equivalence.
Example system: Cell phone. Company A manufactures a cell phone that will
last for 6 years of normal use, while Company B's phone is designed to last
only 3 years. On a true functional equivalence basis, two company B phones
would be required to provide the same years of use as one company A phone.
However, if the average consumer replaces their cell phone after 3 years in
order to upgrade to the latest technology, then both phones would be replaced
after 3 years, and the company A phone would not remain in use long enough
to show a durability benefit over the company B phone.
In some cases, the characteristics of different products make it impossible
to compare them on a completely equivalent basis. For example, carpet, hard-
wood, and ceramic tile all provide the same basic function of covering a given
area of interior floor surface. The life cycle assessment can take into account
the differences in the composition, manufacture, useful lifetime, care and
maintenance during use, and end-of-life management for the different floor
coverings. However, a square meter of carpeted floor still has very different
properties and qualities than a square meter of hard surface floor covering.
A consumer making a decision about the type of floor covering to use in a
kitchen or bedroom would not consider carpet, hardwood, and tile to be com-
pletely equivalent flooring options.
An important consideration when comparing packaging systems is protec-
tive performance. The function of packaging is to deliver undamaged product
to a consumer. The environmental impacts associated with production of the
product inside the package are typically much greater than the impacts asso-
ciated with the package. Therefore, if one type of package is more effective
in protecting product than another package, the differences associated with
product damage can outweigh any environmental impacts associated with dif-
ferences in the packaging. For example, a variety of types and quantities of
packaging shapes can be used to support and protect a computer inside a cor-
rugated box. The environmental impacts for producing the computer are far
greater than the impacts for producing the packaging shapes. Suppose pack-
aging system 1 has higher production impacts than packaging system 2, but
system 1 provides better damage protection than system 2. If use of system 1
prevents damage to even one more computer than system 2, then packaging
system 1 is a better choice.

3.3.2 Boundaries
System boundaries must be defined in terms of the life cycle stages to be
included in the analysis, the geographic and time boundaries of the analysis,
and the flows and impact categories to be included.
Life Cycle Stages. Defining the life cycle stages that will be included in the
scope of the study is a critically important step. Figure 3.1 provides a basic