Temporal Complexity, how time influences life cycle assessments of bio-based materials

Abstract

Environmental harm is an influencing factor in policymaking, as climate pressures are frequently on the global agenda. An important tool to guide decision-making in the construction industry is the life cycle assessment (LCA) methodology, where the quantification of environmental harm is realised. In the method, an estimation of numerous environmental impact indicators can be made by assessing the various life cycles of a product, material, or process. Bio-based materials have been considered a valuable option to mitigate climate change. However, the LCA methodology appears to disregard certain characteristics of the material that could potentially improve their corresponding results. With the growth of bio-based materials, atmospheric carbon is stored as biogenic carbon and subsequently released at the end-of-life, the last life cycle phase of a material. The current methodology is unable to credit such storage, as it models all emissions through the life cycle as if they occurred at the same time. This research aims to explore the various options to comprehend, assess, and credit the storage of biogenic carbon. First, the different approaches to assess the storage of biogenic carbon, that are described in the literature, are assessed. Second, various methods to credit the timing of emissions in the LCA methodology will be elaborated upon. Third, the different currently active European standards are described. For biogenic carbon assessment, three methods were described: the 0/0 method, the -1/1 method, and the dynamic method. Here it was concluded that, respectively, complexity and accuracy increased, making practical implementation difficult but potentially valuable. Especially, the dynamic approach is shown to be a promising tool to accurately assess temporalities within the life cycle of a product. For possible crediting mechanisms, three methods were discussed: the Moura-Costa, Lashof, and ILCD crediting methods. Each method was based on specific assumptions, which resulted in varying credit strengths. In general, each crediting mechanism answered the demand for crediting delayed emissions, but to decide whether one of the methods is better suited than the other, further research is necessary. It is found that the organisational complexity of standardisation within the European Union influences possible alterations in the LCA. However, the research can conclude that the methodology is currently unable to capture the benefits of biogenic carbon storage, and by looking into potential crediting mechanisms, this limitation can be answered. Depending on the demand of our climate and, therefore, of policymakers, possible crediting mechanisms for the storage of biogenic carbon can be considered to be implemented through the LCA methodology.