Abstract
Purpose
This paper aims to investigate the common understanding of the variety of simplifications in LCA, by reviewing what simplification approaches are described in LCA and propose how these simplifications can be categorised. Such an overview can give guidance to researchers/practitioners as to how they should document simplifications and explain their implications to decision-makers.
Methods
The basis for this study is a systematic literature review of simplification approaches in LCA, including both previously published overviews of categories of LCA simplification approaches and LCA case studies using different simplification approaches. The PRISMA statement protocol (Moher et al. 2009) was used to minimise the risk of bias, increase scientific validity and provide guidelines for conducting the review.
Results and discussion
In all, ten categories of simplification were identified in the literature. Initially, six simplification approaches were identified based on previous categories. However, not all approaches found in case studies fit into these six previously published categories; these were therefore examined and grouped with regard to what was simplified and how, and four additional categories were identified.
The identified simplification categories were mapped and explained in terms of their role in the different stages of the LCA framework. Our results support the idea that simplifications in LCA are most often motivated by a lack of data. Most simplifications target the inventory analysis step, with an aim to reduce the inventory analysis effort.
Conclusions and recommendations
There is a need for a common simplification terminology and reporting standard. As this study shows, the categories of simplification from early studies remain relevant despite the development in LCA over the years, but additional categories are needed to cover the different types of simplification being applied in LCAs. What this study also highlights is despite recommendations that have been around for decades, there is still a lack of clear documentation of simplification with consistent terminology. One way, to ensure more transparent documentation of simplified studies and to improve the ability to interpret them and compare results, could be to include the development of a communication standard, with clear terminology as well as investigation of the applicability of different simplification approaches for different product systems and application areas. Due to the wide variety of purposes, scenarios and products assessed, it is impossible to devise a one-size-fits-all approach for simplifications. LCA practitioners need to describe, explain and evaluate the simplifications used.
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