Page 147 - Materials Chemistry, Second Edition

132 A. Bjørn et al.

demand or decrease in supply or who decides to use the product instead of a
substitute due to a decrease in demand or increase in supply, i.e. the marginal user.
However, in reality, identifying the marginal user may be very difficult. Therefore,
if a market analysis shows that the product is used in significant amounts for several
different purposes, it is advised to make different scenarios for each of these
potential substitutions. This can feed into sensitivity and uncertainty analysis of an
LCA (see Sect. 9.6 and Chap. 11). In this case, this step should be followed for
each of the scenarios.
Having identified the marginal product users and what they use the product for,
the next step is to identify what can be used as a substitute for the product by the
different marginal users.
Identifying what will be a satisfying substitute for a specific user will in most
cases require a large amount of background information about the market where the
substitution will take place, and hence involve some elements of uncertainty.
However, for a product to work as a substitute, it needs to fulfil the same functions
for the user. As outlined in Weidema (2003), these may relate to:
• Functionality, related to the main function of the product
• Technical quality, such as stability, durability, ease of maintenance
• Costs related to purchase, use and disposal
• Additional services rendered during use and disposal
• Aesthetics, such as appearance and design
• Image (of the product or the producer)
• Specific health and environmental properties, for example non-toxicity.
Apart from the basic functionality of the product, which can be seen as an
obligatory property of the product (see Chap. 8), the importance of these properties
will to a large extent depend on the product user. If the product user is a company
using the product in its production, the functionality and technical quality will
normally be the most important, for some companies accompanied by health and
environmental issues. For consumers, on the other hand, issues like aesthetics and
image may have a high priority.
It should be noted that there may be not one but several products that work as a
substitute for a product. If it is possible to identify the distribution between the
alternative product substitutes, the consequential LCI should be based on this. If
this is not possible, it may be necessary to develop several scenarios for each of the
likely substitutes.
Product availability
Ensuring that the substitute has the necessary functionality, however, is not
enough. The substitute also has to be available. A substitute is unavailable if
constrained and already used to the extent that the constraint allows. To identify
whether the substitute is available, we need to perform parts of Step 2 (included in
the decision tree below), which also had as a goal to identify the availability of a
product. As the discussion of how to perform this identification is going to be the
same as under Step 2, the reader is referred to this section for further explanation.