Development of a Method for Estimating Uncertainty in Evaluation of Environmental Impacts during Design

Life Cycle Assessment (LCA) is currently the most promising and scientifically defendable technique for estimating environmental impacts of a product during its lifecycle. Currently, detailed LCA is critically dependent on high volumes of product specific data, time consuming, often unaffordable and used in the detailed stages of design. Current approximate LCA methods are either incomplete, inaccurate or require prior knowledge of what data is important. There is substantial uncertainty involved in the environmental impact calculations in LCA. Literature suggests that impact estimation results must be accompanied by an estimation of its uncertainty or imprecision, without which the decisions taken could be misleading. During development of a product, there is often a lack of accurate information about its structure, lifecycle stages, and related environmental impact information. As information about the product lifecycle continues to evolve during development, the assessment method should be such that it incorporates the different levels of abstraction about product information. A key result to be presented in this paper is a preliminary method developed using interval algebra and probabilistic theory taking product structure and lifecycle uncertainties into account. This method helps in estimating impact values of a product proposal in the earlier stages of design by providing an uncertainty value in terms of confidence on the result calculated, with the intention of supporting design decision making.