Page 182 - Materials Chemistry, Second Edition

168 R.K. Rosenbaum et al.

Learning Objectives
After studying this chapter, the reader should be able to:
• Explain and discuss the process and main purposes of the LCIA phase of an
LCA study.
• Distinguish and explain the mandatory and optional steps according to inter-
national standards for LCA.
• Differentiate and describe each of the impact categories applied in LCIA
regarding:
– the underlying environmental problem,
– the environmental mechanism and its fundamental modelling principles,
– the main anthropogenic sources causing the problem,
– the main methods used in LCIA.

10.1 Introduction

In practice, the Life Cycle Impact Assessment (LCIA) phase is largely automated
and essentially requires the practitioner to choose an LCIA method and a few other
settings for it via menus and buttons in LCA software. However, as straightforward
as that may seem, without understanding a few basic, underlying principles and the
meaning of the indicators, neither an informed choice of LCIA method nor a
meaningful and robust interpretation of LCA results are possible. However, the
important extent of science and its inherent multidisciplinarity frequently result in a
perceived opacity of this phase. This chapter intends to open the black box of LCIA
with its characterisation models and factors, and to accessibly explain (1) its main
purpose and characteristics, (2) the mandatory and optional steps according to ISO
and (3) the meaning and handling of each impact category. While this chapter is a
pedagogical and focused introduction into the complex and broad aspects of LCIA,
a more profound and in-depth description, targeting experienced LCA practitioners
and scientists, can be found in Hauschild and Huijbregts (2015).
Once the Life Cycle Inventory (LCI) is established containing all elementary
flows relevant for the product system under assessment, the next question to answer
will be something like: How to compare 1 g of lead emitted into water to 1 g of
CO 2 emitted into the air? In other words, how to compare apples with pears? Life
Cycle Impact Assessment is a phase of LCA aiming to assess the magnitude of
contribution of each elementary flow (i.e. emissions or resource use of a product
system) to an impact on the environment. Its objective is to examine the product
system from an environmental perspective using impact categories and category
indicators in conjunction with the results of the inventory analysis. This will pro-
vide information useful in the interpretation phase.
As the focal point of this phase of an LCA (and also of this chapter), it is a
relevant question to ask what is an environmental impact? It could be defined as a