Material impact perspectives
Understanding the material life-cycle of your design, system or product is the goal of this topic. We’ll use a technique called [Life-Cycle
Analysis](https://en.wikipedia.org/wiki/Life-cycle_assessment) (LCA), detailed in [ISO standard
14040](https://www.iso.org/obp/ui/#iso:std:iso:14040:ed-2:v1:en). Conducting an LCA is a large undertaking, which requires access to a lot of information. For the purposes of ENGN2226, we’ll examine only one part of the LCA process - conducting a material audit. An LCA can be undertaken on any process, such as a manufacturing or construction process, or an entire business or enterprise.
Steps
To conduct a material audit, you will need to be able to:
- construct a table of all of the the materials involved in the process or design
- measure or approximate the mass or volume of each material
- apply an impact metric to understand the material impact of the process or design
—————– ———————- ———————— —————- PART SHAFT HEAD
MAT. OAK STEEL
QTY 400 g 600 g
EMBODIED ENERGY x 2.0 MJ/KG = 0.8 MJ x 20.1 MJ/KG = 12.6 MJ TOTAL: 13.4 MJ
Once an audit has been conducted, you can explore opportunities to reduce the material impact of your design, such as material substitution or reduction.
Key concepts
- an explanation of the steps to conduct a material audit of a system
- an example that walks through a material audit, and measures the impact using an appropriate metric
- advice to the student engineer on how to reduce the material impact of a design, process or system
Core resources
- US Life-Cycle Inventory Database, a list of processes and flows of certain materials
- Weidama, B.P., 2000, Editorial: Increasing Credibility of LCA, International Journal of LCA
- Guidelines for Social Life-Cycle Assessment of Products by the UNEP (excellent resource!){: .link-ext target=”_blank” }
Impact metrics
There are alternative metrics to embodied energy that can be explored once you have conducted a material audit. Such measures include:
-
Embodied energy: see the YourHome guide. Also explore the whole YourHome.gov.au website.
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Carbon footprint: see the Inventory of Carbon & Energy atthe Circular Ecology site
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Water footprint: National geographic’s water footprint calculator (see the methodology)
End-of-life issues
Once a product moves beyond its useful life-span, there is often a lot of waste material. Understanding how you can improve your design to either reduce the waste materials, or improve the reusability of products will become more and more important in a resource-constrained world.