Kari-Anne Lyng

Comparison of two versions of an EPD, using generic and specific data for the foreground system, and some methodological implications

PurposeDifferences in the practice of inclusion and the definition of specific and generic data when performing an LCA for an Environmental Product Declaration (EPD) may lead to incomparable EPDs. The purpose of this paper is to illuminate the importance of precise definitions regarding data quality in EPDs.MethodThe authors define relevant terminology before describing methodological differences between two versions of EPDs for an office chair. The analyses performed for one EPD use generic data for the foreground system, while the other uses specific data. Results for some impact categories as well as inventory findings are shown, and the reasons for differences are investigated and discussed.ResultsRelevant dilemmas are examined with regard to the choice of generic or specific data. These include practical hindrances and the promotion of environmental improvement. Some preliminary methodological and organisational implications are described, followed by an outline of further research.ConclusionsThis paper shows the substantial variations arising from using two datasets with different degrees of specificity, and concludes that they increase in relation to the distinctiveness of the process or material. This highlights the importance of EPD programmes in establishing precise, unambiguous definitions and vocabulary with regard to specific as against generic data, when combined with foreground and background processes. It is essential to take this into consideration so as to avoid misunderstandings or false agreement when discussing data quality. It is also necessary in order to avoid comparisons of products based on very different assumptions.

The BioValueChain model: a Norwegian model for calculating environmental impacts of biogas value chains

PurposeThe BioValueChain model facilitates the calculation of environmental impacts throughout the value chain for production of biogas from organic waste and manure in Norway. This paper describes the methodology of the model, presents the results based on general data and performs a sensitivity analysis for the input data.MethodsThe model is based on life cycle assessment methodology and defines the boundaries of the system and a set of default parameter values which can easily be changed to obtain relevant results for a specific region or a specific biogas plant.Results and discussionThe general results from application of the model show that the application of biogas and digestate, including the assumption regarding which products are substituted, has significance for the results. The sensitivity analysis reveals that results for global warming potential (GWP) appear to be less sensitive for the different parameter values than the other environmental indicators. Increased biogas production from source separated organic household waste and manure from cattle and pigs appears to be an appropriate greenhouse gases (GHG) mitigation measure for Norwegian conditions if the biogas substitutes fossil fuels and if the digestate substitutes mineral fertiliser.ConclusionsThe results underline the need for the use of specific data, especially for transport distances, biogas potential and efficiency of biogas plant. Furthermore, in order to decrease the uncertainty of the results, more research is required into ways of modelling and quantifying direct emissions from the storage and application of manure and digestate on land.