Page 88 - Materials Chemistry, Second Edition

Chapter 7

Life cycle assessment: applications in the built
environment

Ralph E Horne

7.1 Introduction
The built environment is where most Australians spend the majority of their time. This includes
homes, commercial, retail and leisure developments, and the transport and services infrastruc-
ture to support these facilities. Here, the main emphasis will be on buildings, since this is mostly
where life cycle assessment (LCA) has been applied in the built environment to date.
Buildings are a significant component of the human environment and, accordingly, con-
tribute both to the economy and environmental impacts, including global climate change.
They also present a ‘classic’ LCA problem, since they consume considerable amounts of
material and energy (and therefore create impacts) during at least two major life cycle phases:
construction and occupation. There is therefore a longstanding debate over the optimal balance
between the following strategies:
s minimising material use
s investing in more materials to create a more energy-efficient building, which reduces
impacts through the occupation phase.
This issue will be discussed later in the chapter. Another significant issue concerns the
maintenance and alteration of buildings. The built environment is continually being reno-
vated, refurbished and added to, providing considerable opportunities to use LCA in optimis-
ing interventions and specifications. Indeed, in housing alone, reinvestment in existing housing
is about A$16 billion per annum in Australia (in 2005), which is the same order as investment
in new housing construction, yet reinvestment incurs relatively little environmental regula-
tion. In addition, Australians have been adding to the total building stock at 3.8%
(A$35.5 billion) per annum in recent years, and in the three years to 2004/05, spent $77.7 billion
per annum on a combination of new buildings and alterations and additions to existing build-
ings: that is, 9.3% of Gross Domestic Product (DEWR 2007). Across OECD countries includ-
ing Australia, buildings consume 30% to 50% of available raw materials and account for 25%
to 40% of final energy consumption, while generating about 40% of total waste to landfill
(OECD 2002, 2003).

7.1.1 Towards sustainable built environments
Globally, most of the built environment is located in cities, and there are challenges to be
overcome before cities can progress significantly towards sustainability (Girardet 2004).

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