LCA Credibility


Due to the complexity of tracing and researching material flows, it is important to understand how to determine the credibility of an LCA before including it in your own research. According to Pedersen Weidema (2000), LCAs must:


  • “Be understood and perceived as a reasonable basis for decisions by the intended audience

  • Be implemented into decision making and industrial practice without unnecessary controversy

  • Communicate the reliability of their results in terms of uncertainty, based on assessment of the data quality of the information used

  • Be critically reviewed according to the ISO procedures at a high level of excellence” (p.63)


A critical component to judging the credibility and reliability of an LCA study is the inclusion of sensitivity analyses (which list the uncertainties and assumptions made, as well as noting the lack of resources for a material) and the redefinition of the system boundaries based on the iterative research process. Pedersen Weidema (2000) explains that the uncertainties in LCAs create important qualitative results; however, many people consider the quantitative results to be the most credible. Qualitative analyses include uncertainties and create comparisons by changing these variables. Qualitative analyses quickly discover the most significant processes and components of a material and base their analysis on this. Whereas quantitative analysis does not initially determine the most significant processes, and thereby executes a comprehensive LCA before determining the most significant aspects. However, it is important to know how significance is defined. Some argue that significance can be based on mass of a material in the Inventory. For example, if a product is 60% wood, then this strategy would assume that the wood would have the greatest environmental impact. However, this is not necessarily true. Let’s say that the same material is 5% plastic and that plastic has much greater environmental impacts than wood. It would be inaccurate to base the LCA exclusively on the wood, since the less massive materials may be of greater environmental consequence.


Critical reviews of LCA are important in order to establish a robust report. Pedersen Weidema (2000) lists the requirements for critical review:


  • “publish a guide on how to perform peer reviews at a high level of excellence,

  • gather peer reviewers, practitioners and commissioners to discuss difficult aspects of the peer reviewing procedure and ways to enhance performance,

  • publish examples of good practice” (p. 64)



How  are  Products  Selected  for  an  LCA?


LCAs require substantial funding. For this reason, not every product has an LCA. The products/materials that are studied typically are competitive products in the marketplace. Also, many industries will fund an LCA for a product. It is important to know who is funding and reviewing the LCA because this could lead to a misrepresentation of the data. Third party organizations are typically going to be more credible than the representative industry.


If a product is new to the market or does not have much competition, then it is unlikely that an LCA will be performed for that product. An example in building materials is straw bale. Straw bale is an alternative insulation material (and sometimes structure), but since it lacks a predefined industrial standard for manufacturing and is not a popular building material choice, there is no LCA available for this product. If a product is not highly processed or manufactured, it is more difficult to create an LCA. Many natural products which are processed at a local level, typically do not belong to a large industry that regulates the properties and processing of the material.


Sources: Pedersen Weidema, B. (2000). Increasing credibility of LCA. International Journal of LCA; 5 (2), 63-64.