Edinburgh Napier University

  Industrial ecology can potentially become the science of the circular economy as a recent call for papers of the Journal of Industrial Ecology demonstrates. Well known tools in industrial ecology can be employed to analyse different dimensions of the circular economy, such as environmental and resources implications. One widely adopted of such tools is certainly life cycle assessment (LCA) which has been increasingly used in the past 20 years to assess environmental impacts and support ‘sustainability’ claims about products and processes. LCA is a powerful tool if adopted by following strictly the principles and recommendations set out in standards, regulations, and guidelines such as the ISO 14000 series. However, two of such principles are often neglected in practice: sensitivity and uncertainty analysis. Additionally, there is a strong tendency by the LCA community of practice to ignore data distribution and focus and use merely mean values to gauge environmental impacts of the product/process under scrutiny. This paper reports on an example in the construction industry where sensitivity and uncertainty analyses have been used to strengthen LCA results. Data uncertainty has also been carefully evaluated through Monte Carlo simulation in order to determine numerically the effects of focusing solely on mean values. Findings show that by taking into account the uncertainty distribution of the results these can vary by as much as 50%. Additionally, at the end of a building’s life where components and assembly can be either recycled or landfilled the use of mean values neglects and completely overlooks both the burden of a landfill and the positive impact of recycling. As such, most numerical outcomes of current LCAs could potentially be severely flawed and stronger efforts are urgently needed by the LCA community at large to overcome such limitations.