Abstract
Purpose
Identification of key inputs and their effect on results from Life Cycle Assessment (LCA) models is fundamental. Because parameter importance varies greatly between cases due to the interaction of sensitivity and uncertainty, these features should never be defined a priori. However, exhaustive parametrical uncertainty analyses may potentially be complicated and demanding, both with analytical and sampling methods. Therefore, we propose a systematic method for selection of critical parameters based on a simplified analytical formulation that unifies the concepts of sensitivity and uncertainty in a Global Sensitivity Analysis (GSA) framework.
Methods
The proposed analytical method based on the calculation of sensitivity coefficients (SC) is evaluated against Monte Carlo sampling on traditional uncertainty assessment procedures, both for individual parameters and for full parameter sets. Three full-scale waste management scenarios are modelled with the dedicated waste LCA model EASETECH and a full range of ILCD recommended impact categories. Common uncertainty ranges of 10 % are used for all parameters, which we assume to be normally distributed. The applicability of the concepts of additivity of variances and GSA is tested on results from both uncertainty propagation methods. Then, we examine the differences in discernibility analyses results carried out with varying numbers of sampling points and parameters.
Results and discussion
The proposed analytical method complies with the Monte Carlo results for all scenarios and impact categories, but offers substantially simpler mathematical formulation and shorter computation times. The coefficients of variation obtained with the analytical method and Monte Carlo differ only by 1 %, indicating that the analytical method provides a reliable representation of uncertainties and allows determination of whether a discernibility analysis is required. The additivity of variances and the GSA approach show that the uncertainty in results is determined by a limited set of important parameters. The results of the discernibility analysis based on these critical parameters vary only by 1 % from discernibility analyses based on the full set, but require significantly fewer Monte Carlo runs.
Conclusions
The proposed method and GSA framework provide a fast and valuable approximation for uncertainty quantification. Uncertainty can be represented sparsely by contextually identifying important parameters in a systematic manner. The proposed method integrates with existing step-wise approaches for uncertainty analysis by introducing a global importance analysis before uncertainty propagation.
Similar content being viewed by others
References
Archer GEB, Saltelli A, Sobol IM (1997) Sensitivity measures, ANOVA-like techniques and the use of bootstrap. J Stat Comput Simul 58:99–120
Bala A, Raugei M, Benveniste G, Gazulla C, Fullana-i-Palmer P (2010) Simplified tools for global warming potential evaluation: when “good enough” is best. Int J Life Cycle Assess 15:489–498
Bojacá CR, Schrevens E (2010) Parameter uncertainty in LCA: stochastic sampling under correlation. Int J Life Cycle Assess 15:238–246
Borgonovo E, Castaings W, Tarantola S (2011) Moment independent importance measures: new results and analytical test cases. Risk Anal 31:404–428
Bourgault G, Lesage P, Samson R (2012) Systematic disaggregation: a hybrid LCI computation algorithm enhancing interpretation phase in LCA. Int J Life Cycle Assess 17:774–786
Ciroth A, Fleischer G, Steinbach J (2004) Uncertainties in LCA uncertainty calculation in life cycle assessments—a combined model of simulation and approximation. Int J Life Cycle Assess 9(4):216–226
Clavreul J, Guyonnet D, Christensen TH (2012) Quantifying uncertainty in LCA-modelling of waste management systems. Waste Manag 32:2482–2495
Clavreul J, Baumeister H, Christensen TH, Damgaard A (2014) An environmental assessment system for environmental technologies. Environ Model Softw 60:18–30
European Commission-Joint Research Centre-Institute for Environment and Sustainability (2010) International Reference Life Cycle Data System (ILCD) handbook : analysing of existing environmental impact assessment methodologies for use in life cycle assessment
Groen EA, Heijungs R, Bokkers EAM, de Boer IJM (2014) Methods for uncertainty propagation in life cycle assessment. Environ Model Softw 62:316–325
Heijungs R (1996) Identification of key issues for further investigation in improving the reliability of life-cycle assessments. J Clean Prod 4(3–4):159–166. doi:10.1016/S0959-6526(96)00042-X, ISSN 0959–6526
Heijungs R (2010) Sensitivity coefficients for matrix-based LCA. Int J Life Cycle Assess 15:511–520
Heijungs R, Kleijn R (2001) Numerical approaches towards life cycle interpretation five examples. Int J Life Cycle Assess 6:141–148
Heijungs R, Lenzen M (2014) Error propagation methods for LCA—a comparison. Int J Life Cycle Assess 19:1445–1461
Heijungs R, Suh S, Kleijn R (2005) Numerical approaches to life cycle interpretation—the case of the Ecoinvent’96 database. Int J Life Cycle Assess 10:103–112
Hong J (2012) Uncertainty propagation in life cycle assessment of biodiesel versus diesel: global warming and non-renewable energy. Bioresour Technol 113:3–7
Hong J, Shaked S, Rosenbaum RK, Jolliet O (2010) Analytical uncertainty propagation in life cycle inventory and impact assessment: application to an automobile front panel. Int J Life Cycle Assess 15:499–510
Huijbregts MAJ (1998) Part II: dealing with parameter uncertainty and uncertainty due to choices in life cycle assessment. Int J Life Cycle Assess 3:343–351
Huijbregts MAJ, Gilijamse W, Ragas AMJ, Reijnders L (2003) Evaluating uncertainty in environmental life-cycle assessment. A case study comparing two insulation options for a Dutch one-family dwelling. Environ Sci Technol 37:2600–2608
Imbeault-Tétreault H, Jolliet O, Deschênes L, Rosenbaum RK (2013) Analytical propagation of uncertainty in life cycle assessment using matrix formulation. J Ind Ecol 17:485–492
Jensen MB, Kromann M, Lund Neidel T, Bjørn Jakobsen J, Møller J (2013) Miljø- og samfundsøkonomisk vurdering af muligheder for øget genanvendelse af papir, pap, plast, metal og organisk affald fra dagrenovation. Miljøprojekt nr 1458
Kioutsioukis I, Tarantola S, Saltelli A, Gatelli D (2004) Uncertainty and global sensitivity analysis of road transport emission estimates. Atmos Environ 38:6609–6620
Laurent A, Bakas I, Clavreul J, Bernstad A, Niero M, Gentil E, Hauschild MZ, Christensen TH (2014a) Review of LCA studies of solid waste management systems—part I: lessons learned and perspectives. Waste Manag 34:573–588
Laurent A, Clavreul J, Bernstad A, Bakas I, Niero M, Gentil E, Christensen TH, Hauschild MZ (2014b) Review of LCA studies of solid waste management systems—part II: methodological guidance for a better practice. Waste Manag 34:589–606
Lloyd SM, Ries R (2007) Characterizing, propagating and analyzing uncertainty in life-cycle assessment. A survey of quantitative approaches. J Ind Ecol 11:161–179
Meinrenken CJ, Kaufman SM, Ramesh S, Lackner KS (2012) Fast carbon footprinting for large product portfolios. J Ind Ecol 16:669–679
Meinrenken CJ, Sauerhaft BC, Garvan AN, Lackner KS (2014) Combining life cycle assessment with data science to inform portfolio-level value-chain engineering. J Ind Ecol 18:641–651
Padey P, Beloin-saint-pierre D, Girard R, Le-Boulch D, Blanc I (2012) Understanding LCA results variability : developing global sensitivity analysis with Sobol indices. Int Symp Life Cycle Assess Constr Civ Eng Build
Saltelli A, Ratto M, Tarantola S, Campolongo F (2006) Sensitivity analysis practices: strategies for model-based inference. Reliab Eng Syst Saf 91:1109–1125
Saltelli A, Annoni P, Azzini I, Campolongo F, Ratto M, Tarantola S (2010) Variance based sensitivity analysis of model output. Design and estimator for the total sensitivity index. Comput Phys Commun 181:259–270
Sobol’ I (2001) Global sensitivity indices for nonlinear mathematical models and their Monte Carlo estimates. Math Comput Simul 55:271–280
Acknowledgments
The authors wish to thank the anonymous referees for the very perceptive and insightful comments. Financial support is acknowledged from the Danish Research Council through the IRMAR project grant, as well as from the Technical University of Denmark.
Author information
Authors and Affiliations
Corresponding author
Additional information
Responsible editor: Adisa Azapagic
An erratum to this article is available at http://dx.doi.org/10.1007/s11367-016-1259-6.
Rights and permissions
About this article
Cite this article
Bisinella, V., Conradsen, K., Christensen, T.H. et al. A global approach for sparse representation of uncertainty in Life Cycle Assessments of waste management systems. Int J Life Cycle Assess 21, 378–394 (2016). https://doi.org/10.1007/s11367-015-1014-4
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11367-015-1014-4