Life Cycle Impact Assessment (LCIA) methods can be grouped into two families: classical methods determining impact category indicators at an intermediate position of the impact pathways (e.g. ozone depletion potentials) and damage-oriented methods aiming at more easily interpretable results in the form of damage indicators at the level of the ultimate societal concern (e.g. human health damage). The Life Cycle Initiative, a joint project between UNEP1 and SETAC2, proposes a comprehensive LCA framework to combine these families of methods. The new framework takes a world-wide perspective, so that LCA will progress towards a tool meeting the needs of both developing and developed countries. By a more precise and broadly agreed description of main framework elements, the Life Cycle Initiative expects to provide a common basis for the further development of mutually consistent impact assessment methods.
Inputs to the LCIA midpoint-damage framework are results of Life Cycle Inventory analyses (LCI). Impact pathways connect the LCI results to the midpoint impact categories with the corresponding indicators, as well as to the damage categories at the level of damages to human health, natural environment, natural resources and man-made environment, via damage indicators. Mid-point impact categories simplify the quantification of these impact pathways where various types of emissions or extractions can be aggregated due to their comparable impact mechanisms. Depending on the available scientific information, impact pathways may be further described up to the level of damage categories by quantitative models, observed pathways or merely by qualitative statements. In the latter case, quantitative modelling may stop at mid-point. A given type of emission may exert damaging effects on multiple damage categories, so that a corresponding number of impact pathways is required. Correspondingly, a given damage category may be affected jointly by various types of emissions or extractions. It is therefore an important task of the Life Cycle Initiative to carefully select damage indicators. The content of the midpoint and of the damage categories is clearly defined, and proposals are made on how to express the extent of environmental damage by suitable indicator quantities.
The present framework will offer the practitioner the choice to use either midpoint or damage indicators, depending on modelling uncertainty and increase in results interpretability. Due to the collaboration of acknowledged specialists in environmental processes and LCIA around the globe, it is expected that - after a few years of effort - the task forces of the Life Cycle Initiative will provide consistent and operational sets of methods and factors for LCIA in the future.
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In environmental assessments of products, co-products should be dealt with by use of system expansion. This theoretical consensus has existed for some time. However, till now still many environmental assessments are based on economically or mass allocated data. The LCAfood database is the first consistent model of Danish food-production, with a widespread use of system expansion. Using quantified as well as more qualitative knowledge on market structures and production economics, the affected processes are identified for a range of basic food products, in agriculture as well as in food processing industry. It is crucial to identify which technologies are affected by a product demand prior to data collection, as the work can be focused on the most important processes, and the explanatory power of the environmental assessment can be maximised.
The subject of this guideline is some of the first elements of a life cycle study, typically following immediately after the definition of the goal of the study (see also figure 2), namely:
• the determination of relevant product functions and product alternatives (i.e the object of the study),
• the definition of the functional unit, and the determination of the reference flows.
These elements can often be decisive for the results of a specific life cycle assessment. Therefore, it is important that these elements are performed with diligence.
The purpose of this guideline is to provide an unambiguous procedure for these elements of life cycle assessments.
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The Society of Environmental Toxicology and Chemistry (SETAC) Europe launched the Working Group on Scenario Development in LCA to explore, examine, and develop a basis for scenarios in LCA and their importance to future product systems and environmental impacts. A result of 4 years of deliberation by the working group, this book introduces scenarios in LCA through in-depth discussions and recommendations of methods for future studies. Scenarios in Life-Cycle Assessment provides a basis for further analyses, discussions, and development to fill the gap in knowledge of scenarios in LCA.
The subject of this guideline is the geographical, technological and temporal delimitation of the product systems included in life cycle assessments (LCAs).
The purpose of life cycle assessments is to assess the environmental impacts of a choice of one product instead of another (or the choice of a specific product instead of refraining from this product). A specific choice of product may involve changes in processes and their environmental impacts throughout the life cycle of the products. For the assessment to give meaningful results, the affected processes must be identified as precisely as possible, with respect to geography, time, and technology.
The guideline contains three complementary procedures, to be used in parallel or in iteration:
1. A procedure for identifying the processes affected by a change in demand
resulting from a choice between products.
2. A procedure for identifying the processes affected when the choice involves
multi-product systems that provide their products in different proportions. The procedure modifies the systems so that they provide the same products in the same proportions.The procedure is illustrated with examples, including situations of material recycling and complex situations with several co-products from the same process and where several of the involved processes in a system expansion have multiple products or applications.
3. A procedure for identifying future processes. The procedure includes determination of the parts of the product systems that need to be forecasted, the necessary detail of forecasting, and the choice of the relevant forecasting methods. Different forecasting methods and their relevance in different situations are described.
The aim of the three procedures is to reduce the arbitrariness in performing these crucial elements of a life cycle assessment. The procedures are equally relevant for detailed, quantitative life cycle assessments and for qualitative and simplified studies, “screenings” and “matrix-LCAs”.
The three procedures all seek to identify the consequences of a choice between products, which implies a change in demand. Therefore, the procedures include the use of market information. Thereby, the procedures provide a supplement to the traditional approach to system delimitation in life cycle assessment, which typically has been forced to disregard the actual market conditions and instead apply a number of specific (implicit or explicit) assumptions.
Co-production (the combined or joint production of two or more products from the same process or system) has been seen as presenting a problem to the system modelling in life cycle assessment, and the traditional solution has been co-product allocation (the partitioning and distribution of the environmental exchanges of the co-producing process or system over its multiple products according to a chosen allocation key) in parallel to cost allocation. Compared to this traditional solution, system expansion according to ISO 14041 provides a more realistic modelling of the actual consequences of product related management decisions. Through a number of examples, including recycling of steel and aluminium, it is demonstrated how co-product allocation can be avoided in practice. The example of platinum-group metals is used to illustrate how system expansion may sometimes be used as a justification for economic allocation.
The quantification of resource depletion in Life Cycle Assessment has been the topic of much debate; to date no definitive approach for quantifying effects in this impact category has been developed. In this paper we argue that the main reason for this extensive debate is because all methods for quantifying resource depletion impacts have focussed on resource extraction.
To further the state of the debate we present a general framework for assessing the impacts of resource use across the entire suite of biotic and abiotic resources. The main aim of this framework is to define the necessary and sufficient set of information required to quantify the effects of resources use.
Our method is based on a generic concept of the quality state of resource inputs and outputs to and from a production system. Using this approach we show that it is not the extraction of materials which is of concern, but rather the dissipative use and disposal of materials. Using this as a point of departure we develop and define two key variables for use in the modelling of impacts of resource use, namely the ultimate quality limit, which is related to the functionality of the material, and backup technology. Existing methodologies for determining the effects of resource depletion are discussed in the context of this framework.
We demonstrate the ability of the general framework to describe impacts related to all resource categories: metallic and non-metallic minerals, energy minerals, water, soil, and biotic resources (wild or domesticated plants and animals).
We focus on suggestions for a functionality measure for each of these categories; and how best the two modelling variables derived can be determined.
Although both cost-benefit analysis (CBA) and life cycle assessment (LCA) have developed from engineering practice, and have the same objective of a holistic ex-ante assessment of human activities, the techniques have until recently developed in relative isolation. This has resulted in a situation where much can be gained from an integration of the strong aspects of each technique. Such integration is now being prompted by the more widespread use of both CBA and LCA on the global arena, where also the issues of social responsibility are now in focus. Increasing availability of data on both biophysical and social impacts now allow the development of a truly holistic, quantitative environmental assessment technique that integrates economic, biophysical and social impact pathways in a structured and consistent way. The concept of impact pathways, linking biophysical and economic inventory results via midpoint impact indicators to final damage indicators, is well described in the LCA and CBA literature. Therefore, this paper places specific emphasis on how social aspects can be integrated in LCA.
With a starting point in the conceptual structure and approach of life cycle impact assessment (LCIA), as developed by Helias Udo de Haes and the SETAC/UNEP Life Cycle Initiative, the paper identifies six damage categories under the general heading of human life and well-being. The paper proposes a comprehensive set of indicators, with units of measurement, and a first estimate of global normalisation values, based on incidence or prevalence data from statistical sources and severity scores from health state analogues. Examples are provided of impact chains linking social inventory indicators to impacts on both human well-being and productivity.
It is suggested that human well-being measured in QALYs (Quality Adjusted Life Years) may provide an attractive single-score alternative to direct monetarisation.
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