" DISCLAIMER: The ILO does not take responsibility for content presented on this web portal that is presented in any language other than English, which is the language used for the initial production and peer-review of original content. Certain statistics have not been updated since the production of the 4th edition of the Encyclopaedia (1998)."

Thursday, 24 March 2011 17:19

Life-Cycle Assessment (Cradle-To-Grave)

Written by
Rate this item
(1 Vote)

The need to safeguard the environment for future generations makes it necessary not only to discuss the emerging environmental problems, but to make progress in identifying strategies that are cost-effective and environmentally sound to solve them and to take actions to enforce the measures that result from such discussion. There is ample evidence that enhancing the state of the environment as well as establishing policies to sustain the environment must take on greater priority within this generation and those that follow. While this belief is commonly held by governments, environmental groups, industry, academics and the general public, there is considerable debate on how to achieve improved environmental conditions without sacrificing current economic benefits. Furthermore, environmental protection has become an issue of great political importance, and ensuring ecological stability has been pushed to the top of many political agendas.

Past and present efforts to protect the environment are to a large extent characterized as single-issue approaches. Each problem has been dealt with on a case-by-case basis. With regard to problems caused by point-source pollution from easily identified emissions, this was an effective way of reducing environmental impacts. Today, the situation is more complex. Much pollution now originates from a large number of non-point sources easily transported from one country to another. Furthermore, each of us contributes to this total environmental pollution load through our daily patterns of living. The different non-point sources are difficult to identify, and the way in which they interact in impacting the environment is not well known.

The increasing environmental problems of more complex and global character will most likely entail great implications for several sectors of society in enforcing remedial actions. To be able to play a role in environmental protection, sound and universal policies must be applied jointly as an additional, multi-issue approach by all those actors taking part in the process—the scientists, trade unions, non-governmental organizations, companies and agencies of authority at the national and governmental levels, as well as the media. Therefore, it is important that all areas of sectoral interest be coordinated in their environmental ambitions, in order to get necessary interactions and responses to proposed solutions. It is likely that there may be a unanimous view with regard to the ultimate objectives of better environmental quality. However, it is equally likely that there may be disagreement about the pace, means and time required to achieve them.

Environmental protection has become a strategic issue of increasing importance for industry and the business sector, both in the siting of plants and in the technical performance of processes and products. Industrialists are increasingly becoming interested in being able to look holistically at the environmental consequences of their operations. Legislation is no longer the sole dimensioning factor following the growing importance of product-related environmental issues. The concepts of environmentally sound product development and environmentally friendly or “green” products are assuming wider acceptance among producers and consumers.

Indeed, this is a great challenge for industry; yet environmental criteria are often not considered at the beginning of the design of a product, when it may be easiest to avoid adverse impacts. Until recently, most environmental impacts were reduced through end-of-pipe controls and process design rather than product design. As a result, many companies spend too much time fixing problems instead of preventing them. A great deal of work, however, is needed to develop a suitable and accepted approach to incorporate environmental impacts into the various production stages and industrial activities—from raw material acquisition and manufacture to product use and final disposal.

The only known concept to deal with all these new complex issues seems to be a life-cycle approach to the problem. Life-cycle assessments (LCAs) have been widely recognized as an environmental management tool for the future, as product-related issues assume a more central role in the public debate. Although LCAs promise to be a valuable tool for programmes on cleaner production strategies and design for the environment, the concept is relatively new and will require future refinement to be accepted as a general tool for environmentally sound process and product development.

The Business Framework for Life-Cycle Assessment

The necessary new approach to environmental protection in the business sector, to look at products and services in their totality, must be linked to development of a common, systematic and structured approach which enables relevant decisions to be made and priorities to be set. Such an approach must be flexible and expandable to cover various decision-making situations in industry as well as new input as science and technology progress. However, it should rest upon some basic principles and issues, for example: problem identification, survey of remedial measures, cost/benefit analysis and final assessment and evaluation (figure 1).

Figure 1. Outline of consecutive steps for setting priorities in decisions on  environmental protection measures in industry

ENV040F1

The problem identification ought to highlight different types of environmental problems and their causes. These judgements are multidimensional, taking into account various background conditions. There is indeed a close relationship between the work environment and the external environment. The ambition to safeguard the environment should therefore include two dimensions: to minimize the burden on the external environment following all kinds of human activities, and to promote the welfare of employees in terms of a well-planned and safe work environment.

A survey of potential remedial measures should include all the available practical alternatives for minimizing both pollutant emissions and the use of non-renewable natural resources. The technical solutions should be described, if possible, giving their expected value both in reducing resource use and pollution loads as well as in monetary terms. The cost/benefit analysis aims at producing a priority list by comparing the different identified approaches of remedial measures from the perspectives of product specifications and requirements to be met, economic feasibility and ecological efficiency. However, experience has shown that great difficulties often arise when seeking to express environmental assets in monetary terms.

The assessment and evaluation phase should be regarded as an integral part of the procedure of setting priorities to give the necessary input for the final judgement of the efficiency of the suggested remedial measures. The continuous exercise of assessment and evaluation following any measure that is implemented or enforced will give additional feedback for optimization of a general decision model for environmental priority strategies for product decision. The strategic value of such a model will likely increase in industry when it becomes gradually apparent that environmental priorities might be an equally important part of the future planning procedure for new processes or products. As LCA is a tool for identifying the environmental releases and evaluating the associated impacts caused by a process, product or activity, it will likely serve as the major vehicle for industry in their search for practical and user-friendly decision-making models for environmentally sound product development.

Concept of Life-Cycle Assessment

The concept of LCA is to evaluate the environmental effects associated with any given activity from the initial gathering of raw material from the earth until the point at which all residuals are returned to the earth. Therefore, the concept is often referred to as a “cradle-to-grave” assessment. While the practice of conducting life-cycle studies has existed since the early 1970s, there have been few comprehensive attempts to describe the full procedure in a manner that would facilitate understanding of the overall process, the underlying data requirements, the inherent assumptions and possibilities to make practical use of the methodology. However, since 1992 a number of reports have been published focusing on describing the various parts of a LCA from a theoretical viewpoint (Heijungs 1992; Vigon et al. 1992; Keoleian and Menerey 1993; Canadian Standards Association 1993; Society of Environmental Toxicology and Chemistry 1993). A few practical guides and handbooks have been published taking on the specific perspectives of product designers in making practical use of a complete LCA in environmentally sound product development (Ryding 1996).

LCA has been defined as an objective process to evaluate the environmental burdens associated with a process, product, activity or service system by identifying and quantifying energy and materials used and released to the environment in order to assess the impact of those energy and material uses and releases to the environment, and to evaluate and implement opportunities to effect environmental improvements. The assessment includes the entire life cycle of the process, product, activity or service system, encompassing extracting and processing raw materials, manu-facturing, transportation and distribution, use, reuse, maint-enance, recycling and final disposal.

The prime objectives of carrying out LCA are to provide as complete a picture as possible of the interactions of an activity with the environment, to contribute to the understanding of the overall and interdependent nature of environmental consequences of human activities and to provide decision-makers with information which identifies opportunities for environmental improvements.

The LCA methodological framework is a stepwise calculation exercise comprising four components: goal definition and scoping, inventory analysis, impact assessment and interpretation. As one component of a broader methodology, none of these components alone can be described as an LCA. LCA ought to include all four. In many cases life-cycle studies focus on the inventory analysis and are usually referred to as LCI (life-cycle inventory).

Goal definition and scoping consists of a definition of the purpose and the system of the study—its scope, definition of the functional unit (the measure of performance which the system delivers), and the establishment of a procedure for quality assurance of the results.

When initiating an LCA study, it is of vital importance to clearly define the goal of the study, preferably in terms of a clear and unambiguous statement of the reason for carrying out the LCA, and the intended use of the results. A key consideration is to decide whether the results should be used for in-company applications to improve the environmental performance of an industrial process or a product, or whether the results should be used externally, for example, to influence public policy or consumer purchase choices.

Without setting a clear goal and purpose for the LCA study in advance, the inventory analysis and the impact assessment may be overdone, and the final results may not be properly used for practical decisions. Defining whether the results should focus on environmental loads, a specific environmental problem or a holistic environmental impact assessment will directly clarify whether to conduct an inventory analysis, classification/characterization or a valuation (figure 2). It is important to make all consecutive LCA components “visible” in order to make it easier for any user to choose the level of complexity they wish to use.

Figure 2.  Purposes and completeness of life-cycle assessment

ENV040F2

In many general programmes for cleaner production strategies, design for the environment or environmentally sound product development, the principal objective is often to lower the overall environmental impact during a product’s life cycle. To meet these demands it is sometimes necessary to arrive at a highly aggregated form of the environmental impact assessment which in turn emphasizes the need for identifying a general accepted valuation approach for a scoring system to weigh the different environmental effects against each other.

The scope of an LCA defines the system, boundaries, data requirements, assumptions and limitations. The scope should be defined well enough to ensure that the breadth and depth of analysis are compatible with and sufficient to address the stated purpose and all boundaries, and that assumptions are clearly stated, comprehensible and visible. However, as an LCA is an iterative process, it may be advisable in some cases not to permanently fix all aspects included in the scope. The use of sensitivity and error analysis is recommended to make possible the successive testing and validation of the purpose and scope of the LCA study versus the results obtained, in order to make                                                                                                                         corrections and set new assumptions.

Inventory analysis is an objective, data-based process of quantifying energy and raw material requirements, air emissions, waterborne effluents, solid waste and other environmental releases throughout the life cycle of a process, product, activity or service system (figure 3).

Figure 3. Stepwise elements in a life-cycle inventory analysis.

ENV040F3

The calculation of inputs and outputs in the inventory analysis refers to the system defined. In many cases, processing operations yield more than one output, and it is important to break down such a complex system into a series of separate sub-processes, each of which produces a single product. During the production of a construction material, pollutant emissions occur in each sub-process, from raw material acquisition to the final product. The total production process may be illustrated by a “process tree” where the stem may be seen as the main chain of flow of materials and energy, whereas the branches may illustrate sub-processes and the leaves the specific figures on pollutant emissions and so on. When added together, these sub-processes have the total characteristics of                                                                                                                         the original single system of co-products.

To estimate the accuracy of the data gained in the inventory analysis, a sensitivity and error analysis is recommended. All data used should therefore be “labelled” with relevant information not only as to reliability but also source, origin and so on, to facilitate future updating and refinement of the data (so-called meta-data). The use of a sensitivity and error analysis will identify the key data of great importance for the outcome of the LCA study that may need further efforts to increase its reliability.

Impact assessment is a technical, qualitative and/or quantitative process to characterize and assess the effects of the environmental loading identified in the inventory component. The assessment should address both ecological and human health considerations, as well as other effects such as habitat modifications and noise pollution. The impact assessment component could be characterized as three consecutive steps—classification, characterization and valuation—all of which interpret the effects of environmental burdens identified in the inventory analysis, on different aggregated levels (figure 4). Classification is the step in which the inventory analyses are grouped together into a number of impact categories; characterization is the step in which analysis and quantification takes place, and, where possible, aggregation of the impacts within the given impact categories is carried out; valuation is the step in which the data of the different specific impact categories are weighted so that they can be compared amongst themselves to arrive at a further interpretation and aggregation of the data of the impact assessment.

Figure 4. Conceptual framework for the successive level of data aggregation in the impact assessment component

ENV040F4

In the classification step, the impacts may be grouped in the general protection areas of resource depletion, ecological health and human health. These areas may be further divided into specific impact categories, preferably focusing on the environ-mental process involved, to allow a perspective consistent with current scientific knowledge about these processes.

There are various approaches to characterization—to relate data to no-observable-effect concentrations or to environmental standards, to model both exposure and effects and apply these models in a site-specific way, or to use equivalency factors for the different impact categories. A further approach is to normalize the aggregated data for each impact category to the                                                                                                                         actual magnitude of the impacts in some given area, to increase                                                                                                                     the comparability of the data from the different impact categories.

Valuation, with the aim of further aggregating the data of the impact assessment, is the LCA component that has probably generated the most heated debates. Some approaches, often referred to as decision theory techniques, are claimed to have the potential to make the valuation a rational, explicit method. Valuation principles may rest on scientific, political or societal judgements, and there are currently approaches available that cover all three perspectives. Of special importance is the use of sensitivity and error analysis. The sensitivity analysis enables the identification of those selected valuation criteria that may change the resultant priority between two process or product alternatives because of the uncertainties in the data. The error analysis may be used to indicate the likelihood of one alternative product being more environmentally benign than a competitor product.

Many are of the opinion that valuations have to be based largely on information about social values and preferences. However, no one has yet defined the specific requirements that a reliable and generally accepted valuation method should meet. Figure 5 lists some such specific requirements of potential value. However, it should be clearly emphasized that any valuation system for assessing the “seriousness” of environmental impacts of any human activity must be largely based on subjective value judgements. For such valuations it is probably not possible to establish criteria which are tenable in all situations worldwide.

Figure 5. List of suggested requirements to be met for a LCA valuation method

ENV040F5

Interpretation of the results is a systematic evaluation of the needs and opportunities to reduce the environmental burden associated with energy and raw materials use and waste emissions throughout the whole life cycle of a product, process or activity. This assessment may include both quantitative and qualitative measures of improvements, such as changes in product design, raw material use, industrial processing, consumer demands and waste management.

Interpretation of the results is the component of an LCA in which options for reducing the environmental impacts or burdens of the processes or products under study are identified and evaluated. It deals with the identification, evaluation and selection of options for improvements in processes and product design, that is, technical redesign of a process or product to minimize the associated environmental burden while fulfilling the intended function and performance characteristics. It is important to guide the decision-maker regarding the effects of the existing uncertainties in the background data and the criteria used in achieving the results, to decrease the risk of making false conclusions regarding the processes and products under study. Again, a sensitivity and error analysis is needed to gain credibility for the LCA methodology as it provides the decision-maker with information on (1) key parameters and assumptions, which may need to be further considered and refined to strengthen the conclusions, and (2) the statistical significance of the calculated difference in total environmental burden between the process or product alternatives.

The interpretation component has been identified as the part of an LCA that is least documented. However, preliminary results from some large LCA studies carried out as comprehensive efforts by people from academia, consultancy firms and many companies all indicated that, from a general perspective, significant environmental burdens from products seem to be linked to the product use (figure 6). Hence, the potential seems to exist for industry-motivated initiatives to minimize environmental impacts through product development.

Figure 6. Outline of some general experiences of where in the life-cycles of  products the major environmental burdens occur

ENV040F6

A study on international experiences of environmentally sound product development based on LCA (Ryding 1994) indicated that promising general applications of LCA seem to be (1) for internal use by corporations to form the basis for providing guidance in long-term strategic planning concerning product design, but also (2) to some extent for use by regulatory agencies and authorities to suit general purposes of societal planning and decision-making. By developing and using LCA information regarding environmental effects that are both “upstream” and “downstream” of the particular activity under scrutiny, a new paradigm may be created for basing decisions in both corporate management and regulatory policy-making.

Conclusion

Knowledge about human threats to the environment seems to grow faster than our ability to solve them. Therefore, decisions in the environmental arena must often be taken with greater uncertainties present than those in other areas. Furthermore, very small safety margins usually exist. Present ecological and technical knowledge is not always sufficient to offer a complete, fool-proof strategy to safeguard the environment. It is not possible to gain full understanding of all ecological responses to environmental stress before taking action. However, the absence of complete, irrefutable scientific evidence should not discourage making decisions about and implementation of pollution abatement programmes. It is not possible to wait until all ecological questions are scientifically substantiated before taking action—the damage that may result through such delays could be irreversible. Hence, the meaning and scope of most problems is already known to a sufficient extent to justify action, and there is, in many cases, sufficient knowledge at hand to initiate effective remedial measures for most environmental problems.

Life-cycle assessment offers a new concept to deal with the future complex environmental issues. However, there are no shortcuts or simple answers to all questions posed. The rapidly emerging adoption of a holistic approach to combat environmental problems will most likely identify a lot of gaps in our knowledge about new aspects that need to be dealt with. Also, available data that may be used are in many cases intended for other purposes. Despite all difficulties, there is no argument for waiting to use LCA until it gets better. It is by no means hard to find difficulties and uncertainties in the present LCA concept, if one wants to use such arguments to justify an unwillingness to conduct an LCA. One has to decide whether it is worthwhile to seek a holistic life-cycle approach to environmental aspects despite all difficulties. The more LCA is used, the more knowledge will be gained about its structure, function and applicability, which will be the best guarantee for a feedback to ensure its successive improvement.

To make use of LCA today may be more a question of will and ambition than of undisputed knowledge. The whole idea of LCA ought to be to make the best use of present scientific and technical knowledge and to make use of the result in an intelligent and humble way. Such an approach will most likely gain credibility.

 

Back

Read 13391 times Last modified on Friday, 19 August 2011 18:46

Contents

Preface
Part I. The Body
Part II. Health Care
Part III. Management & Policy
Part IV. Tools and Approaches
Part V. Psychosocial and Organizational Factors
Part VI. General Hazards
Part VII. The Environment
Part VIII. Accidents and Safety Management
Part IX. Chemicals
Part X. Industries Based on Biological Resources
Part XI. Industries Based on Natural Resources
Part XII. Chemical Industries
Part XIII. Manufacturing Industries
Part XIV. Textile and Apparel Industries
Part XV. Transport Industries
Part XVI. Construction
Part XVII. Services and Trade
Part XVIII. Guides