Page 98 - Materials Chemistry, Second Edition

Life cycle assessment: applications in the built environment

and shows how greenhouse gas emissions would not be reduced overall without either strin- 85
gent measures beyond those modelled and/or the coupling of these measures with others (e.g.
a major switch to renewable electricity generation away from fossil fuels). This analysis excludes
efficiencies achieved through optimisation at design and construction stages. These and other
approaches would therefore be required in order to achieve a net reduction in total impacts
from 2005 levels.
7.2.2.2 Discussion
The use of LCA clearly illustrates the potential relative ‘savings’ of different strategies. Among
these strategies, a reduction in the number and size of buildings (or projected new buildings)
provides the most significant potential greenhouse gas savings. The study also indicates that a
range of interventions is required if the rise in buildings-related greenhouse gas emissions is to be
arrested – and then reduced. Since much of the environmental impact of buildings is determined
at the design stage, through materials decisions, in-built efficiencies and performance criteria
incorporated into the design, the next area for impact reduction is improvements in building
design. This was beyond the scope of the current study and is undoubtedly a fertile area for
further research. For today’s building designers and specifiers, it can be difficult and costly to
obtain credible environmental performance information, and some form of widely recognised
labelling would assist where there is demand for environmentally preferable building materials.
However, additional measures to support application of ESD and sustainable building materials,
such as additional building code requirements, are also important in driving uptake.
The study found that the environmental costs of increasing primary industry and raw
materials extraction, where this is required to improve buildings and materials environmental
performance, are likely to be small and insignificant compared to the benefits obtained over
the building life cycle. However, significant life cycle impacts occur at end-of-life, either
through direct impacts (emissions and outputs to the environment, and energy inputs to proc-
esses) or through the lost recycling opportunity and associated additional requirements for
new materials. About 60% of construction and demolition waste is recycled. The rate of
recovery tends to be higher for metals and other high value materials, but many materials that
are recycled, such as concrete, are ‘down-cycled’ into roadbase and other low value uses. Eco-
nomically, there is significant potential benefit from increasing resource recovery. Preliminary
analysis suggests that recovering an additional 5% to 10% of the value of building materials
currently resulting from demolition (i.e. 5% to 10% of A$1.5 billion, or A$75–150 million per
annum) may be a reasonable target.
A further option to reduce greenhouse gas emissions and other environmental pollution
and resource impacts is to optimise materials individually through process, manufacturing
and supply-chain innovation. This includes improving product durability. Specification for
best life cycle performance within given assemblies can be achieved through the provision of
credible tools and information applicable to a wide range of settings, with appropriate drivers
(regulatory and/or voluntary) to assist uptake.
Finally, designing for the life of buildings – alterations, ‘churn’ (refits) and design for disas-
sembly – and applying such activities in efficiency-maximising ways has considerable potential
to reduce impacts, while also providing economic benefits to building owners, facility managers
and tenants over the building’s life. For example, using an ‘open building’ system allows altera-
tions in the building layout without significant construction work. This involves separating
the structure from the cladding and providing access to all parts of the building and all com-
ponents, which can help to minimise impacts through maintenance. Similarly, using compo-
nents that are sized to suit the intended means of handling can reduce waste during materials
use at all stages.

100804•Life Cycle Assessment 5pp.indd 85 17/02/09 12:46:19 PM