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Sustainability and the built environment
Specification of materials for use in the construction industry can be assisted by life
cycle assessment (also known as life cycle analysis). This benchmarking tool aims
to make the sourcing of sustainable building materials less time-consuming for the
designer by assisting in the process of determining the origins of a product. ‘Life
cycle assessment is used to evaluate the environmental burdens associated with a
particular product, process or activity, by identifying energy and materials used and
wastes released to the environment, and evaluating and implementing opportunities to
affect environmental improvements’ (SETAC, 1990).
Embodied energy
Assessing the energy associated with the manufacture and distribution of an item
presents problems. As with the carbon footprint calculation in Section 4, there are up-
and downstream considerations. Energy consumed during extraction, processing and
manufacture is called embodied energy (sometimes ‘embedded’ or ‘hidden’ energy),
but its full extent in relation to a particular product is difficult to calculate accurately.
As an example, take the raw material extraction necessary to produce a simple steel
beam. Should the energy used by mine employees (transporting themselves to and
from the mine) and the energy used in manufacturing the plant and equipment used in
the mine to process the ore be included in the life cycle analysis?
Most life cycle analysis calculations are limited to upstream factors and therefore
give a value for the material to the point of specification. However, the overall
embodied energy for many items, from houses to washing machines, shows that
energy consumed during their lifetime far outweighs energy consumed during their
manufacture. This is important to bear in mind when determining the total lifespan of
a product, especially if the product is of the magnitude of a building. The longer the
lifespan, the lower the initial energy consumption will be as a proportion of the total
energy consumed. Whatever its limitations, the life cycle analysis tool is a reminder
that products often come at a much higher cost than might be expected.
Selecting sustainable materials and products increases their popularity, thereby
driving up levels of their consumption. Unfortunately, this increased consumption can
sometimes render such products and materials unsustainable themselves.
6.2 Energy
The main response to climate change is reducing energy consumption, but the
advantages of addressing energy issues go beyond this. On a macro scale there is
reduced pollution and a reduced risk of supply interruptions. At a micro level it can
reduce or eliminate running costs. It will, of course, also conserve resources for future
use.
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