INNOVATION September-October 2014

A Canadian Example: Comparing Dollars to Dollars When the Bank of Canada was considering changing the substrate material of bank notes from cotton paper to polymer, it conducted a cradle-to-grave life cycle assessment comparing the two alternatives. The boundaries chosen for this study are illustrated below.

Resources (materials and energy resources)

System boundaries

Cotton production

Polymer production

Foil

Paper production

Polymer conversion

Foil

Thread

Ink

Ink

Bank note printing

Bank note printing

Plates

Plates

Distribution

Distribution

Use

Use

End of Life

End of Life

Emissions to air, discharges to water and soil

Identifying boundaries, inputs, and outputs is part of any LCA

After the system boundaries were established, indicators were chosen for the analysis. Those conducting the study had to ask themselves, “What costs or impacts should be considered?” The indicators chosen in this example were: primary energy demand, global warming potential, eutrophication potential, acidification potential, smog potential and human and ecosystem toxicity. Next, the study broke the life cycle into manageable stages that could be considered separately: manufacturing, distribution and end-of-life. The report concluded that the polymer bank note has lower overall lifetime costs and therefore it was the preferred option. A major factor in the competitive advantage of the polymer notes was their durability. Polymer notes have an expected lifetime of 7.5 years, while their paper counterparts are expected to last only three years in circulation. The Art of LCA: Reduce, Reuse, Recycle While the above example is comprehensive in its scope of impacts studied, it is also relatively linear, moving from inputs to outputs. Best-practice sustainable designs, like natural ecosystems, are not always this straightforward, as techniques both modern and ancient allow materials to be reused or recycled to optimize their usefulness and mini- mize waste. These “loops” can take place either within the system boundaries (known as closed-loop recycling) or by finding symbiotic relationships with agencies outside the system boundaries (known as open-loop recycling). These loops, when incorporated into the scope of an LCA study, can dramatically reduce the life cycle costs and impacts

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