Page 64 - Materials Chemistry, Second Edition

46 LIFE CYCLE ASSESSMENT HANDBOOK

or differences in the use phase of the product. If the properties and per-
formance of each of the systems analyzed is the same, the systems can be
compared on a one-to-one basis. However, there are often differences in the
systems that must be taken into consideration when defining the functional
unit and scope of the analysis. Some differences are relatively simple to
accommodate.
For example, consider a comparative analysis of two multi-serving bever-
age containers with differences in capacity. Since the function of each container
is to deliver beverage to the consumer, an appropriate basis of comparison
would be delivery of an equivalent number of fluid ounces or servings. To
deliver the equivalent volume of beverage, fewer of the larger volume contain-
ers would be required.
In the preceding example, the beverage inside the containers was the same,
and only the container sizes were different. A related example is products
that deliver the same functional service with different volumes of packag-
ing due to differences in the form of product. Examples include concentrated
detergent compared to pre-diluted detergent, condensed soup compared to
ready-to-serve soup, and pre-ground coffee compared to coffee beans. In each
case, the condensed or more compact version of the product requires less
packaging to deliver the same number of servings or uses. It is worth not-
ing, however, that differences in concentration may introduce differences in
the product use phase. Preparation of condensed soup, for example, requires
the consumer to put the soup into a larger container for dilution and heating
prior to serving. This results in additional container washing burdens for the
condensed soup compared to ready-to-serve soup packaged in a microwave-
able container that serves a dual function of packaging and serving the soup.
Purchasing pre-ground coffee rather than coffee beans eliminates the need for
the consumer to grind the coffee prior to use. A comparison of pre-ground cof-
fee with coffee beans would thus need to include not only the differences in
packaging requirements but also the differences in commercial grinding and
home grinding operations.
In other cases, data may not be available to precisely quantify functional
differences between systems, or there may be differences due to consumer
behavior rather than the inherent properties of the product, as in the following
examples:
Example 1. Functional equivalence varies from use to use within the
defined application. Example system: Disposable plates. The function
of a disposable plate is to hold a quantity of food. Some plates are very
lightweight and will only support a few ounces of food, while other plates
are heavier and sturdier and can hold much greater loads. For a light duty
use (such as a piece of cake or some snack crackers), a single plate of either
type will be sufficient to support the load, and the plates will have a one-
to-one functional equivalence. However, if the intended application is a full
meal that includes heavier items, then two or more lightweight plates may
be required to hold the same amount of food that can be placed on a single
heavyweight plate. In cases where functional equivalence can vary within