According to the ISO 14040 standard on life cycle assessments, there are 4 stages of an LCA: (1) Goal and Scope, (2) Inventory Analysis, (3) Impact Assessment, and (4) Interpretation. We explored Inventory Analysis, which ISO 14040 defines as “the…
Blog Archives
Sensitivity Analysis: Testing the Significance of Your Assumptions
A Life Cycle Assessment is only as good as the data and assumptions built in the LCA. As we described in the previous post on developing the function unit, many informed assumptions needed to be made about use patterns of…
Life Cycle Impact Assessment: Calculating Environmental Impacts
In previous posts, we described how to construct a model of the manufacture, transportation, use, and disposal of a product from unit processes and reference flows. This process is Life Cycle Inventory (LCI) analysis. According to the ISO 14040 standard…
Stating the Assumptions: Geographic Relevance and LCAs
Last post, we described how LCA models are built from unit processes, and demonstrated how the end of life scenarios for facial tissues is constructed from the following 4 unit processes from the Ecoinvent database: Disposal, paper, 11.2% water, to…
Unit Processes: The Building Blocks of Life Cycle Assessments
In the last post, we explored how reference flows are calculated, by making careful, thought-out assumptions and well-applied research. In our exploration of the Ecosystem Analytics Inc. LCA on cloth handkerchief use versus disposable facial tissues, we demonstrated how reference…
Reference Flows in a Complex World: Making Appropriate Assumptions
Last post, we introduced the concept of reference flows, which are a measure of the outputs from processes required to fulfill the function expressed by the functional unit of the LCA. We also illustrated how the reference flows are calculated…
Reference Flows: The Work Horses of Life Cycle Assessments
In the previous post on quantifying the functional unit, I described the studies, assumptions, and calculations used to develop the reference amount used to compare two product alternatives. Since LCA is based on the function of the product, and since…
System Boundaries: Looking at the Whole Picture
Life Cycle Assessments aim to understand the impacts of products, services, and organizations over the entire life cycle, from manufacture and disposal. Still, even when a LCA does model impacts from cradle-to-grave, there still can be deviances from what is…
How Functional Units Are Developed and Quantified
As I described in the previous post, the functional unit serves as the reference unit for the study, normalizing all inputs and outputs to it, and enables comparisons between products with similar functions. It is generally expressed in qualitative terms,…
The Functional Unit: the Heart of all Life Cycle Assessments
At the American Center for Life Cycle Assessment LCAXII Conference recently held in Tacoma, Washington, Vee Subramanian and Eric Williams gave an interesting talk on “Uncertainty due to Inadequacy of Functional Units” in the Uncertainty 1 session. The functional unit,…