Presentation on theme: "School of Civil and Building Services Engineering"— Presentation transcript:
1 School of Civil and Building Services Engineering Comparative Analysis of Life Cycle Inventory Techniques and Development of a Quantitative Uncertainty Analysis ProcedureDeidre WolffSchool of Civil and Building Services EngineeringProf. Aidan DuffyProf. Geoff HammondNov. 29, 2013
2 Life Cycle Assessment (LCA) ‘The compilation and evaluation of the inputs, outputs, and potential environmental impacts of a product system throughout its life cycle’ (ISO 14044, 2006)
3 Goal Definition and Scope Life Cycle Assessment (LCA)Four Stages:Goal and Scope DefinitionLife Cycle Inventory (LCI)Life Cycle Impact Assessment (LCIA)InterpretationGoal Definition and ScopeInventory AnalysisInterpretationImpact Assessment(ISO 14040)
4 MotivationLCA is often used in decision-making processes and to inform policyLCA involves using expert judgement, assumptions, data of poor quality, allocation and weightingThese all introduce uncertaintyUncertainty is often ignored in LCA studies due to lack of knowledge and/or time and budget constraints
5 ObjectivesConduct Process, Input-Output, and Hybrid LCA of a simple system, quantifying overall uncertainty for each modelCompare the results obtained using different LCI methodsDevelop a technique to make comparisons between studies that have applied different LCI methodsApply methodology to a building, using a Bill of Quantities (BoQ) as a data sourceDetermine a suitable LCI and uncertainty analysis methodology to apply to all LCA studies in the built environment
6 What is uncertainty?Errors originating from inaccurate measurements, lack of data, and model assumptions (Huijbregts, 1998) The problem of using information that is unavailable, wrong, unreliable, or that shows a certain degree of variability (Heijungs, 2004)
7 Uncertainty Classification in LCA Parameterdata uncertaintyarises due to incomplete knowledge of true value of data, lack of data or measurement errorModelunknown interactions between model formulations, due to simplification, derivation of characterization factors, aggregation of data into impact categoriesScenariodue to decisions made during the LCA, such as choice in system boundary, functional unit, allocation, weighting factors
10 Case-study: Process LCA Goal and Scope:Determine the overall Global Warming Potential for the production of an electric kettle, using data from EcoInvent Database.System boundary is cradle-to-gate, including raw material extraction and manufacturing of the materials used for the production of a kettle.The system boundary is simplified, as the overall goal of the LCA is to quantify the uncertainty.
11 Case-study: Process LCA Energy InputEnergy InputEnergy InputEnergy InputTransport of Electric Kettle to ConsumerRaw Material ExtractionTransport to production facilityAssembly of Electric KettleEnergy InputEnergy InputEmissions to AirEmissions to AirEmissions to AirEmissions to AirDisposal/ RecyclingUse PhaseEmissions to AirEmissions to Air
12 System Diagram Stainless Steel Silicone Kettle Copper Poly-propylene The emissions associated with energy consumed during these steps has been ignored for simplificationStainless Steel437 gPoly-propylene245.5 gBody of Kettle682.9 gSilicone0.4 gAssemblygKettleStainless Steel15 gPoly-propylene310.2 g355.6 gElectrical ComponentCopper41.9 g3.5 gPolyamide
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