Page 17 - Materials Chemistry, Second Edition

Life Cycle Assessment: Principles, Practice and Prospects
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LCA of two coffee machines may indicate that the more durable, heavily built of the two has
the higher environmental impact, if the product comparison is based on the product level. If,
however, it is based on the functional level, we may find that the more durable product has a
life-span which enables it to produce five times as many cups of coffee over its lifetime. Not-
withstanding any functional differences in coffee quality, aesthetic quality, obsolescence or
maintenance, this quality alone may reverse the outcome of the LCA comparison, simply by
taking as the functional unit ‘impact per production of 10 000 cups of coffee’ rather than
‘impact per coffee machine’.
The most well-known application of LCA is in comparing the ‘total’ environmental impact
of a product or service with an alternative (comparable) product or service. UNEP refers to
LCA as a tool to reveal ‘the world behind the product’ (Fava 2002). Hence, LCA is often consid-
ered a tool that provides ‘the answer’ to the question of which product has least environmental
impact. However, LCA can reveal things other than the answer. It can also fail to reveal the
answer at all, if the question is not precisely and appropriately framed (see Chapter 4 for further
discussion of this point).
Defining the scope involves determining the appropriate limits of the analysis. This
includes identifying the entire production and disposal or recycling process of the materials
and services involved in the life cycle of the product or service being studied (and any com-
parative product or service). The components involved in delivering the product or service
should be included, as well as all inputs to those components, and the inputs to those inputs,
and so on. It also includes the outputs, emissions and wastes produced at all stages of the
product or service delivery – both ‘pre-consumption’ and ‘post-consumption’. Decisions may
be taken to ‘truncate’ the system for practical purposes, and quick estimates of impacts more
distant from the central processes may be undertaken to check that they are negligible and can
be disregarded from a detailed assessment.
The resultant ‘process chains’ in the products or services under comparison may be signifi-
cantly different. For example, a wool carpet and a synthetic carpet (for which an appropriate
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functional comparison might be ‘the provision of 1 m of carpet for 10 years’) would have very
different process chains, one being dominated by agricultural inputs and processes, the other
by industrial ones. This example also raises the issue of allocation of impacts; while sheep
farming produces wool, it also produces other animal products and the total impact of sheep
farming is therefore only partly attributable to wool, with the remainder attributable to meat,
hide and other sheep farming products.
The inventory is the result of compiling all environmental ‘flows’, including resource use
inputs and waste or pollution outputs. This inventory provides a lower estimate of the environ-
mental burdens that the product or service places upon the environment. However, the relative
importance of these burdens requires some measure or indicator of impact. Inventory data can
only be converted into impact results through the use of appropriate algorithms or indicators
of environmental burden related to damage or importance. This is where primary fossil fuel
energy used in delivering the product or service is converted into climate impacts, local air
pollution, and so on. A range of eco-indicator and related environmental impact factors have
been developed for use in LCA. However, ISO 14040 acknowledges that these must not be
blindly applied to different temporal, spatial and product or service conditions. Hence, all
results must be subject to reflective interpretation by an experienced LCA practitioner.

1.3 LCA and environmental management
LCA has considerable data requirements, and the ‘question’ – goal and scope – must be care-
fully framed. Indeed, LCA uptake has arguably been compromised by these difficulties.

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