Life Cycle Assessment (LCA): A Guide to Best Practice

Abstract

Life cycle assessment (LCA) is a systems-oriented methodology for addressing the environmental consequences associated with a product or service.It is used for studies of the material and energy flows and their environmental impacts related to a product or a service, i.e., from raw material extraction, to production and use, to disposal.LCA, together with life cycle thinking, life cycle management, and life cycle sustainability assessment, makes up the portfolio of life cycle approaches. Methodological FrameworkLife cycle assessment (LCA) study is defined both by the product system it models and the procedure used to study it, the LCA model and the LCA procedure, respectively.The LCA model describes the flow system from raw material extraction to waste disposal, including production, transportation, use, and recycling loops associated with a product (or a service).The procedure consists of several steps.The analysis starts with the definition of goal and scope, in which the researchers specify the product(s) to be studied and the purpose of the LCA study.In the inventory analysis, they construct the life cycle model consisting of the technical processes of the product system, create an inventory of emissions and resource usage in each process, and then calculate the amounts of emissions produced and the resources used in the product system.Results at this stage are called life cycle inventory (LCI) results and consist of amounts of raw materials, energy, and emissions.Next, in the impact assessment, the LCI results are translated into environmental impacts.Owing to the complexity of ecological systems and environmental impacts, impacts can be evaluated in various ways.Emissions and resource use can be classified, characterized, and normalized with regard to their potential or contribution to various environmental problems (e.g., resource depletion, global warming, and toxicity).Some environmental problems have been easier to make assessment methods for (e.g., global warming), whereas others have shown to be more difficult (e.g., toxicity, biodiversity loss) and for which methodology development continues.In the weighting step, the relative significance of the different environmental problems is evaluated.This leads to the calculation of a sum of the total environmental impact for the studied product system.There are several weighting methods, each representing different perspectives on prioritization of environmental problems, e.g., cultural, economic, or political values, or ecological boundaries.Whether one presents results as LCI results, characterized impacts or weighted impact depends too on the purpose of the study, determined by, for example, what is appropriate for public communication and what is useful for internal use.Finally, the