Life Cycle Assessment is used to compare the environmental impact of products and processes across their full lifespan. It is also one of the most easily manipulated tools in industrial practice, depending entirely on how the system boundary is drawn.
LCA Outputs vs. What They Actually Mean
| LCA Output | What It Measures | Common Misuse |
| Carbon footprint | GHG emissions across defined stages | Excluding upstream supplier emissions |
| Water use impact | Volume and regional scarcity weighting | Reporting volume only, ignoring scarcity |
| Energy demand | Primary energy from all sources | Counting renewable electricity as zero-impact |
| Toxicity potential | Chemical releases and receptor exposure | Omitting use-phase chemical releases |
A Specific Boundary Decision That Changes Everything
A packaging manufacturer commissions an LCA comparing virgin plastic to recycled plastic. If the system boundary ends at the factory gate, recycled plastic looks dramatically better. Include transport to sorting facilities, sorting energy, and contamination losses, and the gap narrows considerably.
Neither result is wrong. Both are products of specific methodological choices. ISO 14040 and 14044 set the framework but leave boundary decisions to the practitioner, which is where the subjectivity enters.
When to Trust an LCA Study
Check whether the study has been independently reviewed and whether the system boundary is explicitly stated. Peer-reviewed LCAs published in journals like the International Journal of Life Cycle Assessment are considerably more reliable than those produced by companies for their own marketing purposes.
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