Part 3: Scientific background appendix B of the present Part; Wegener Sleeswijk et al., 1996; Finnveden, 1998; Finnveden, 2000; Wrisberg et al., in prep.). It has become increasingly clear that LCA is but one tool amongst many for environmental analysis. In some circumstances other instruments may be more appropriate: Risk Assessment, for example, if siting aspects are crucial to the issue under investigation. Other tools may be used in parallel to provide better insight into the environmental consequences of a given choice: Substance Flow Analysis (SFA), for example, if one specific flow is of prime importance in the product system investigated, as in the case of rechargeable cadmium batteries. The EU-concerted action CHAINET has dealt with this subject extensively (Wrisberg et al., in prep.). Other authors support the importance of the aforementioned issues, sometimes usefully expanding them into more detailed guidelines. For example, Lindfors et al


Other authors support the importance of the aforementioned issues, sometimes usefully expanding them into more detailed guidelines. For example, Lindfors et al. (1995a) argue that it is not sufficient merely to define the goal in terms of what is to be done, e.g. ‘To compare the environmental impacts associated with paints used for wall decoration’, but that the underlying reason, e.g. To ‘provide information in the setting of criteria for ecolabeling’, also needs to be addressed. They suggest including in the LCA report a clear statement of the intended applications and users. For the particular case of paint they give the following example: The results of the LCA will be used by the ecolabeling board to identify areas where criteria should be set in order to promote the most environmentally friendly products within this product group’. Several authors note, furthermore, that it may be necessary to revise the initial objectives and intended decisions during the course of an LCA (e.g

Guinée et al., Handbook on LCA: Operational Guide to the ISO Standards (2002)


Several authors note, furthermore, that it may be necessary to revise the initial objectives and intended decisions during the course of an LCA (e.g. ISO 14041, 1998E; Lindfors et al., 1995a; Wenzel et al., 1997). Performing an LCA is an iterative rather than purely sequential process. Finally, various references distinguish between different categories of application (e.g. Heijungs et al., 1992; Weidema, 1993; Fleischer et al., 1995; Guinée, 1995; Lindfors et al., 1995a; Braunschweig et al., 1996; UNEP, 1996; ISO 14040, 1997E; Cowell et al., 1997; UNEP, 1999; Wenzel, 1998). The differences between these various categorisation schemes are mainly a matter of taste and not examined as such here. The key question is, rather, whether it is possible to distinguish groups of applications differing in their impact on methodological choices or procedural arrangements in the course of an LCA study


The key question is, rather, whether it is possible to distinguish groups of applications differing in their impact on methodological choices or procedural arrangements in the course of an LCA study. Some authors offer valuable suggestions for a classification of applications as they affect methodological choices (Frischknecht, 1997; Frischknecht, 1998; Clift et al., 1998; Weidema, 1998a; Wenzel, 1998). This subject will be discussed in more detail in Section 2.3 (‘Mode of analysis’). This Guide distinguishes six types of decision situation in which LCA results may be applied (De Bruijn & Van Duin, 1998; Van Duin & De Bruijn, 1998): global exploration of options; company-internal innovation; sector-driven innovation; strategic planning; comparison; comparative assertion disclosed to the public


In the case of comparison of product alternatives, it must be determined at some stage what differences in results are to be deemed significant for concluding that one alternative is environmentally sounder than another. For procedural reasons it seems wise to address this issue as part of the goal definition, at the very outset of the study.


Part 3 : Scientific background Clause 8 of ISO 14041 (1998E) specifies that the study report on the Goal and Scope definition should meet the following requirements (see textbox): The results of an LCI study shall be fairly, completely and accurately reported to the intended audience as described by the relevant parts of clause 6 of ISO 14040:1997E. If a third-party report is required, it shall cover all items marked with an asterisk. All additional items should be considered. a) Goal of the study reasons for carrying out the study *; its intended applications *; the target audiences *


b) Scope of the study: modifications together with their justification; function: Statement of performance characteristics *; ii) Any omission of additional functions in comparisons *; 3) functional unit: i) Consistency with goal and scope *; ii) Definition *; iii) Result of performance measurement *; 4) system boundaries: i) Inputs and outputs of the system as elementary flows; ii) Decision criteria iii) Omissions of life cycle stages, processes or data needs * iv) Initial description of the unit processes; v) Decision about allocation; 5) data categories: i) Decision about data categories; ii) Details about individual data categories iii) Quantification of energy inputs and outputs *; iv) Assumptions about electricity production *; v) Combustion heat *; vi) Inclusion of fugitive emissions; 6) criteriafor initial inclusion of inputs and outputs: i) Description of criteria and assumption *; ii) Effect of selection on result *; iii) Inclusion of mass, energy and environmental criteria


6) criteriafor initial inclusion of inputs and outputs: i) Description of criteria and assumption *; ii) Effect of selection on result *; iii) Inclusion of mass, energy and environmental criteria (comparisons *); 7) data quality requirements


Source: ISO 14041, 1998E. For Goal and Scope definition, Lindfors et al. (1995a) list the following reporting issues: The members of the reference panel or review group shall be reported, if relevant. A short resumé of the discussions in the reference panel shall be given, with focus on conflicting views, or: a report from the reviewer(s) on the critical review, concerned party review, or validation, or: a statement that an external validation or review process has not been carried out, including a justification of that decision (e.g. since concerned parties have been involved in the conduct of the study). The commissioner of the study shall be stated. A presentation of the practitioners, including their background, shall be given (an LCA-oriented C.V.). The purpose shall be clearly and unambiguously stated, in terms of the reasons for carrying out the LCA. A clear statement on the decisions intended to be based on the findings should be made


The purpose shall be clearly and unambiguously stated, in terms of the reasons for carrying out the LCA. A clear statement on the decisions intended to be based on the findings should be made. A statement on the intended users or audience should be made. The main user function(s) (e.g. protection and/or colouring for paints) forming the basis for the LCA shall be clearly defined and reported. Any deviation from initial plans may be reported. Any other limitations or introduced assumptions relevant to the results of the study shall be reported. In its report, the SETAC-Europe Case studies Working Group (Meier et al., 1997) gives the following (minimum) reporting guidelines for the Goal and Scope phase: General study information 1) 2) 3) 1) 2) i)


Part 3: Scientific background As much detail as possible should be included, i.e. authors, affiliations of authors, commissioning body, responsible person at commissioning body, availability, etc. Goal definition The overall objectives of the study should be given in a clear and concise statement with the reasons for carrying out the study and the intended use of the results detailed. The methodology employed should be clearly stated and transparent and any differences in methodology from a full LCA should be explained. All assumptions and value judgements should be clearly detailed along with the justification for the assumptions. These reporting guidelines have also been provided by the Working Group in the form of a practitioners’ checklist. PROSPECTS It might be possible as well as useful to define categories of LCA applications leading to different choices vis-à-vis methodological procedures and for which different Guidelines would therefore be applicable


This might result in better and more consistent results, and in more time- and cost-effective LCA studies. CONCLUSIONS We recommend following the ISO 14041 requirements, supplemented by the suggestions of Lindfors et al. (1995a). In this Guide we furthermore distinguish six different types of decision situations: global exploration of options; company-internal innovation; sector-driven innovation; strategic planning; comparison; comparative assertion disclosed to the public. In the case of comparison of product alternatives, we recommend establishing in the Goal definition step what differences in results are to be deemed significant for concluding that one alternative is environmentally sounder than another. RESEARCH RECOMMENDATIONS Short-term research Definition of categories of applications, with preferred choices of LCA methodology and associated sets of methodological and procedural Guidelines


RESEARCH RECOMMENDATIONS Short-term research Definition of categories of applications, with preferred choices of LCA methodology and associated sets of methodological and procedural Guidelines. Standards-setting, possibly by government, regarding the quality and methodology for LCAs for each of these different applications (i.e. a code of practice for each application). 2.3 Scope definition TOPIC In the scope definition step the main characteristics of an intended LCA study are established, covering such issues as temporal, geographical and technology coverage, the mode of analysis employed and the overall level of sophistication of the study. A so-called goal and scope report may also be drafted for the sake of critical review and comments from interested parties. This report should justify all the main choices with respect to the step ‘Function, functional unit, alternatives and reference flow‘ and the phases of Inventory analysis, Impact assessment and Interpretation.


Part 3 : Scientific background DEVELOPMENTS IN THE LAST DECADE Heijungs et al. (1992) In Heijungs et al. (1992) scope definition did not yet constitute a separate method step. However, the level of sophistication, or depth of the study as it was then called, comprised a separate element of goal definition. A distinction was made between a more detailed and a more streamlined approach. A detailed LCA was considered to be appropriate for important applications such as government approvals or bans. A more simplified approach was considered to be appropriate for certain in-company applications and in LCAs relating to product improvement and design. Simplification was to be achieved by: concentrating on the differences between product alternatives; excluding certain elements of the LCA; limiting the number of processes; limiting the number of environmental effects


It was noted that introducing simplifications might imply decreased reliability, particularly if it is decided to limit the number of processes or environmental effects examined, and that such reduced reliability should be in conformity with the importance of the application. In Heijungs et al. simplified methods were not elaborated in any further detail. The spatial and temporal dimension of the study goal were treated as separate steps in Heijungs et al. With regard to spatial representativeness it was noted that “this must be specified unless it is clear from the specification of the functional unit. The spatial representativeness could global, continental (e.g. European), regional (e.g. EU), national (e.g. the Netherlands) or at company level (e.g. brand X). Also, representativeness like ‘in temperate climates’ may be useful, e.g. in an LCA on insulation materials


EU), national (e.g. the Netherlands) or at company level (e.g. brand X). Also, representativeness like ‘in temperate climates’ may be useful, e.g. in an LCA on insulation materials. The particular spatial representativeness determines which alternative systems can usefully be considered in an LCA study for a specific application (e.g. an LCA study on milk packaging for ecolabeling in the Netherlands may involve different packaging alternatives from the same study for an EU ecolabel).” With regard to temporal representativeness Heijungs et al. states that this should be determined similarly to spatial representativeness. Generally, a rough indication will suffice, for example '1998' or '2010'. Also, representativeness like ‘during summer’ may be useful, especially for seasonal products. Similarly to spatial representativeness, temporal representativeness determines which alternative systems may usefully be compared in an LCA study for a specific application. Finally, Heijungs et al


Similarly to spatial representativeness, temporal representativeness determines which alternative systems may usefully be compared in an LCA study for a specific application. Finally, Heijungs et al. already discussed a hot issue in the present LCA debate, which we shall henceforth refer to as the “mode of analysis”. A basic assumption made by Heijungs et al. (p. 12 of Backgrounds ’92) is that the ceteris paribus principle is applied in product assessments, which means that the choice of the functional unit of the product alternative investigated has no influence on any other activities anywhere on the planet. For example, this means that the effects of the emissions due to the functional unit are assumed to be additional to the normal background concentration. The functional unit was also assumed to be marginal relative to other activities, allowing linear models to be used


The functional unit was also assumed to be marginal relative to other activities, allowing linear models to be used. ISO 14041 (1998E), clause 5.3.1 states the following concerning the scope of the study (see textbox): The scope of the study shall consider all relevant items in accordance with ISO 14040: 1997, 5.1.2. It should be recognised that an LCA study is an iterative technique, and as data and information are collected, various aspects of the scope may require modification in order to meet the original goal of the study. In some cases, the goal of the study itself may be revised due to unforeseen limitations, constraints or as a result of additional information. Such modifications, together with their justification, should be duly documented. Source: ISO 14041, 1998. be


Part 3: Scientific background ISO 14040 (1997E), clause 5.1.2 reads (see textbox): In defining the scope of an LCA study, the following items shall be considered and clearly described: the function of the system the functional unit the system to be studied the system boundaries allocation procedures the types of impact and the methodology of Impact assessment and subsequent Interpretation to be used data requirements assumptions limitations the initial data quality requirements the type of critical review, if any, and the type and format of the report required for the study. The scope should be sufficiently well defined to ensure that the breadth, the depth and the detail of the study are compatible and sufficient to address the stated goal. LCA is an iterative technique. Therefore, the scope of the study may need to be modified while the study is being conducted as additional information is collected. Source: ISO 14040, 1997E


LCA is an iterative technique. Therefore, the scope of the study may need to be modified while the study is being conducted as additional information is collected. Source: ISO 14040, 1997E. The Scope definition is a relatively new step that has not yet received much attention in other LCA literature. As explained in Section 1.4 and taking into account the elements distinguished as part of Scope definition in ISO 14040 and 14041, we propose distinguishing two main elements of the scope of the study: Determining the main characteristics of an intended LCA study: temporal, geographical and technology coverage, coverage of economic processes, coverage of environmental interventions and impact categories, mode of analysis and level of sophistication of the study. Reporting of all the main choices to be made in the ‘Function, functional unit, alternatives and reference flow‘ step and the Inventory analysis, Impact assessment and Interpretation phases


Reporting of all the main choices to be made in the ‘Function, functional unit, alternatives and reference flow‘ step and the Inventory analysis, Impact assessment and Interpretation phases. This yields a so-called Goal and Scope Report, drawn up for critical review and comments from interested parties. These two elements together cover all the ISO issues mentioned in the above text box. Below, the developments of the past decade are discussed as they relate to the main characteristics: temporal, geographical and technology coverage, mode of analysis and level of sophistication of the study. In Part 2a, guidelines are provided for drafting a Goal and Scope Report in Section 1.6 on reporting. Temporal coverage ISO 14041 (1998E), clause 5.3.6 states that temporal coverage refers to: The desired age of data (e.g. within the last five years) and the minimum length of time over which data should be collected (e.g. one year)


within the last five years) and the minimum length of time over which data should be collected (e.g. one year). According to ISO 14041 (1998E) the temporal coverage shall be specified and appropriate data quality requirements defined. The latter point is treated in Section 3.5 of the Inventory analysis. Temporal coverage has become even more important in recent years, as there is a general feeling today that different modes of analysis should be employed for different temporal contexts (see also ‘Mode of analysis’, below). It is thus important to specify a base year or base period for the study, on which other choices can be based. Geographical coverage ISO 14041 (1998E), clause 5.3.6 states that geographical coverage refers to: Geographical area from which data for unit processes should be collected to satisfy the goal of the study (e.g. local, regional, national, continental, global)


local, regional, national, continental, global). According to ISO 14041 (1998E) the geographical coverage shall be specified and appropriate data quality requirements defined. The latter point is treated in Section 3.5 of the Inventory analysis. In 1996 a ‘Groupe des Sages’ published a report on the use of LCA for ecolabeling applications in the EU. They stressed the need to explicitly establish the geographical coverage of an LCA study in certain cases, giving the example of regional differences in water hardness influencing detergent requirements. Regional differences might thus be taken into account in determining the amount of detergent needed to wash a certain amount of laundry optically white. Depending on the precise application of the LCA, this may be a very useful thing to do since it will indicate to consumers how they can minimise the


Part 3 : Scientific background environmental impact of their behaviour, taking into account the regional background (Udo de Haes et al., 1996). The usefulness of including this geographical context depends on the application in question, however. While this may be very useful in a national study, it may not be relevant for a European-average study. Technology coverage ISO 14041 (1998E), clause 5.3.6 states that technology coverage refers to: Technology mix (e.g. weighted average of the actual process mix, best available technology or worstoperating unit). According to ISO 14041 (1998E) the technology coverage shall be specified and appropriate data quality requirements defined. The latter point is treated again in Section 3.5 of the Inventory analysis. The technology coverage taken as the point of departure for data collection in the Inventory analysis should match the geographical and temporal coverage of the study


The technology coverage taken as the point of departure for data collection in the Inventory analysis should match the geographical and temporal coverage of the study. In a European-average study for the year 2000, for example, data on the European state-of-the-art technology being installed in 2000 should be taken; in a Dutch study for that year, the state-of-the-art in the Netherlands for the year 2000 should be used. Thus, for most structural, change-oriented decisions (see below) the data taken should be for the current state-of-the-art technology in the region or country with which the study is concerned (see also Section 3.6). If the LCA study concerns a futuristic system for which technologies are available only as prototypes, it is important to determine the criteria for allowing a prototype technology to be taken into account in the LCA study


For example, it may be important to establish that prototypes should have undergone a certain amount of testing before being eligible for the LCA study and that they are economically feasible1. With some applications it might also be useful for interested parties to come to arrangements for dealing with implementation of prototype technologies after the LCA study (see Section 1.3 on ‘Management of LCA projects: procedures’). As far as is known to the authors of this report, no guidelines have yet been formulated on this issue. Coverage of economic processes (initial system boundaries) Life cycle assessment is defined as a compilation and evaluation of the inputs and outputs and the potential environmental impacts of a product system throughout its life cycle (ISO 14040, 1997E). Ideally, the product system should be modeled in such a manner that all the inputs and outputs at its boundary are environmental interventions (ISO 14041,1998E)


Ideally, the product system should be modeled in such a manner that all the inputs and outputs at its boundary are environmental interventions (ISO 14041,1998E). However, if it is possible to narrow the scope of the life cycle to those stages or subsystems that really matter in relation to the goal of the study, a significant saving of the time and resources spent on an LCA study can be achieved. Todd et al. (1999) and also Christiansen et al. (1997) mention that such narrowing down is feasible within the ISO (quantitative) LCA framework by limiting or eliminating upstream and/or downstream stages (“exclude parts of the life cycle system”). A useful first step in any LCA study, whether simplified, detailed or extended, is to consider whether limiting or eliminating certain life cycle stages (without introducing a mere cut-off) is justified in relation to the goal of the LCA study. A ‘mere cut-off’ here refers to certain life cycle stages or subsystems, e.g


A ‘mere cut-off’ here refers to certain life cycle stages or subsystems, e.g. capital goods or inputs contributing less that a certain percentage to a product or process, being excluded from a study because of time and resource constraints. This subject is treated below (‘Level of sophistication’) and in Section 3.8, but it is not the subject of the present section. Limiting or eliminating life cycle stages may be permissible if the goal of the study allows for a narrower scope with respect to system boundaries without the reliability of the results being reduced. In a study aiming to supply data on a subsystem like aluminium or polyethylene production, for example, it may be justified to narrow the analysis to a cradle-to-gate analysis (i.e. an analysis not going beyond the aluminium or polyethylene production site). Similarly, a gate-to-gate analysis (i.e


an analysis not going beyond the aluminium or polyethylene production site). Similarly, a gate-to-gate analysis (i.e. an analysis of polyethylene film production from polyethylene granulate) can in some cases be performed, narrowing the boundaries even further. The various limitations of these partial LCA studies should obviously be fully realised by the practitioners and users of the ensuing results. Although these studies may serve as an important and useful source of data for other cradle-to-grave LCAs, in themselves they by no means constitute full LCAs. Any conclusions drawn on the basis of such partial LCAs should therefore be formulated with the greatest caution. It may be in order to narrow the boundaries of an LCA for quite different reasons, viz. in the type of LCA here referred to as ‘difference analysis’. In this case it may be opted to exclude from further analysis life cycle stages or subsystems that are similar for each of the (product) systems analysed


In this case it may be opted to exclude from further analysis life cycle stages or subsystems that are similar for each of the (product) systems analysed. This holds only for comparative LCAs, where the aim is to focus on and assess the differences between alternative (product) systems. For example, if the filling and distribution processes for two products are similar, these 1 What is meant by “economically feasible” should then also be established, of course.


Part 3: Scientific background activities might be excluded from the analysis1. However, if one of the products requires refrigeration during filling and distribution activities, with higher energy consumption as a result, then these activities should clearly be addressed (Christiansen et al., 1997). An important condition here is thus that the subsystems excluded are precisely comparable with respect to technologies, properties, qualities and quantities of the flow supplied or produced. An example for which exclusion of subsystems is rather more debatable is food packaging. An item frequently excluded from comparative packaging studies is the product packaged. However, due care should be taken in excluding the product, particularly when product waste or actual consumption is influenced by the characteristics of the packaging (Kooijman, 1993; Heijungs & Guinée, 1995; Christiansen et al., 1997)


Coverage of environmental interventions and impact categories ISO 14040 (1997E), clause 5.1.2.2 states that “the selection of inputs and outputs [...] shall be consistent with the goal of the study”. ISO 14041 (1998E), clause 5.3.4 states that “individual data categories [including environmental interventions - authors’ addition] should be further detailed to satisfy the goal of the study”. In addition ISO 14042 (2000E), clause 5.3 states that “the selection of impact categories shall reflect a comprehensive set of environmental issues related to the product system being studied, taking the goal and scope into consideration”. Although LCA, as defined in this Guide, in principle aims for a broad coverage of environmental interventions and impact categories (see Chapter 1), these ISO quotations leave some scope for restriction. Todd et al. (1999) as well as Christiansen et al


Todd et al. (1999) as well as Christiansen et al. (1997) mention two main options for narrowing the coverage of environmental interventions and impacts: focusing on specific environmental impacts or issues for example); establishing criteria to be used as ‘showstoppers’ or ‘knockouts’, e.g. criteria which can result in an immediate decision when encountered during the study (a black list chemical, for example). Focusing on certain inputs or outputs, in an energy analysis for example, or on certain environmental interventions and/or specific impact categories may be very practical and defensible in the context of a specific goal, but the drawback is that important environmental factors may thus be excluded. The most comprehensive approach is, of course, to include all environmental interventions and impact categories listed by the SETAC-Europe Working Group on Impact assessment (Udo de Haes et al., 1999)


Those environmental interventions and impacts that cannot be quantified for lack of appropriate methodologies and/or data should then be handled in a qualitative manner (and flagged where relevant), developing additional methods and/or calculating additional factors where possible. For a number of categories practical methods are as yet lacking, however. Thus, the best available practical option is to include all impact categories for which practical methods are available and all associated environmental interventions for which factors are available. Environmental interventions encountered in a study for which factors are lacking but which are deemed important in relation to the impact category considered should be handled qualitatively. An extended option here is to calculate new factors for such environmental interventions


An extended option here is to calculate new factors for such environmental interventions. Mode of analysis In general, the term ‘mode of analysis’ might be taken to refer to the specific manner in which methods are employed to answer a particular question. For instance, one might address a certain problem scientifically, qualitatively, dynamically or whatever the case may be. In the context of LCA, however, we employ the term to refer to the two main choices described Section 1.12 change-oriented versus descriptive analysis; occasional versus structural versus strategic choices. In Section 1.1, we chose to focus the discussion and the resulting guidelines on change-oriented analysis in support of structural decisions. Relevant examples are a choice between packaging materials (for a company), a choice between means of transport (for a frequent traveller) and so on


Relevant examples are a choice between packaging materials (for a company), a choice between means of transport (for a frequent traveller) and so on. It was stated that the other modes of analysis, for occasional choices or by means of a descriptive analysis, for example, may be relevant in certain decision contexts. The emphasis on change-oriented analysis and structural decisions was motivated by the need to restrict the topic, on the one hand, and by the broad scope of our interest, on the other. In certain decision contexts this mode of analysis may be inappropriate. In others, it may provide a coarse approximation to the question the LCA is designed to answer. It is difficult to specify exactly what limitations this sets on the scope and validity of the theory developed in the present 1 Another example is waste management


It is difficult to specify exactly what limitations this sets on the scope and validity of the theory developed in the present 1 Another example is waste management. If a waste stream for which two management techniques are being compared is exactly the same for both techniques, the upstream waste management processes may be excluded from further analysis. 2 In that section, we also listed a number of synonyms or related terms that can be found in literature, like prospective LCA.


Part 3 : Scientific background documents and the derived guidelines. In most cases it will suffice for practitioners to provide a qualitative justification of how the study satisfies the terms of change-oriented, structural LCA elaborated in this Guide. With respect to the Scope definition phase, one practical consequence is that the assumptions behind such change-oriented analysis and structural decisions must be justified as being reasonable. It also means that a bad match vis-à-vis these assumptions may lead to results that are inaccurate and of only limited relevance. For instance, a question like ‘Shall I take the car or train for my business trip tomorrow’ is not related to a structural choice and the method described in this Guide may give an erroneous answer when applied to such a question. In the Scope definition it is therefore important to indicate relevant mismatches and effects that may potentially lead to reduced accuracy and restricted usefulness


In the Scope definition it is therefore important to indicate relevant mismatches and effects that may potentially lead to reduced accuracy and restricted usefulness. This obviously cannot take the form of quantitative analysis complete with in-depth error analyses. It will be no more than a qualitative description of possible restrictions with uncertain consequences. However, it may also lead to recommendations to address particular gaps in knowledge. In certain cases, for instance, it might be argued that the topic is more amenable to short-term optimisation using the tools of operations research (e.g. linear programming, cf. Clift et al., 1998). Level of sophistication The fact that LCA is commonly perceived as being extremely complex, time-consuming and expensive may discourage potential users (Christiansen et al., 1997)


Level of sophistication The fact that LCA is commonly perceived as being extremely complex, time-consuming and expensive may discourage potential users (Christiansen et al., 1997). However, it is generally acknowledged that LCA does not refer to one specific method but rather to a framework for systematic and comprehensive environmental assessment of (product) systems. The SETAC-Europe LCA Screening and Streamlining Working Group (Christiansen et al., 1997) and the SETAC North America Streamlined LCA Workgroup (Todd et al., 1999) have suggested that different levels of sophistication of LCA may be required for different decision situations. In line with these suggestions, and to promote broader application of LCA, guidelines might be developed for different levels of LCA sophistication. Christiansen et al


In line with these suggestions, and to promote broader application of LCA, guidelines might be developed for different levels of LCA sophistication. Christiansen et al. (1997) suggest distinguishing between simplified LCA and detailed LCA, providing the following definitions: Simplified LCA: an LCA of reduced complexity produced by the procedure of simplification. Simplification: a procedure to reduce the complexity of an LCA and so reduce the cost, time and effort required to run it. This may entail exclusion of certain life cycle stages, system inputs or outputs, or impact categories, or the use of generic data modules rather than data specific to the system under study. Simplification was considered to consist of three steps: Screening: identification of elements of the LCA that can be omitted or for which generic data can be used without significantly affecting the accuracy of the final result1


Simplifying: application of the simplifying options identified in the screening step to produce a simplified LCA. Assessing reliability: ensuring that the results are reliable enough to justify the conclusions drawn. Streamlined LCA was considered to be synonymous with simplified LCA and streamlining was considered synonymous with simplification, which seems in line with the definitions of the North American Working Group (Todd et al., 1999)2: Using qualitative as well as quantitative data, for example constructing materials-flow diagrams for the processes and materials studied but not always quantifying flows. Using surrogate data (‘use of secondary data sources’), for example using readily available data on a similar process when data on the particular process cannot be obtained. Limiting the process flows studied to those exceeding a certain threshold value. The first option for simplification is applicable to all LCA studies and has already been discussed


Limiting the process flows studied to those exceeding a certain threshold value. The first option for simplification is applicable to all LCA studies and has already been discussed. The remaining options relate basically to the problem of the inventory data. The use of surrogate data or, better, estimates, when process-specific data are lacking has recently been extended from use of public data reports and databases to use of data based on input-output analysis: IOA (Lave et al., 1995; 1 Screening was defined by Christiansen et al. (1997) as a procedure that identifies some particular characteristic or keyissue associated with the LCA that will normallybe the subject offurther, more intensive study. Such keyissues might be: the principal environmental inputs/outputs or environmental impacts associated with the particular life cycle; the stages of the life cycle giving rise to the most significant environmental inputs and outputs; major gaps in the available data. 2 Todd et al


2 Todd et al. (1999) define screening LCA as an application of LCA used primarily to determine whether additional study is needed and the required focus of that study. They define streamlined LCA as the identification of elements of an LCA that can be omitted or for which surrogate or generic data can be used without significantly affecting the accuracy of the results.


Part 3: Scientific background Hendrickson et al., 1998). Since this possibility has been operationalised, there are in fact no longer any grounds for excluding any flows from an LCA study (for an extensive discussion, see Section 3.8). Flows for which specific data are lacking can now be estimated using IOA models. This implies that the main simplification with respect to inventory data is to reduce the number of processes for which specific (primary) data are to be collected. These processes will henceforth be referred to as ‘foreground processes’. Processes for which no specific (primary) data are collected but for which secondary data from databases, public references or lOA-based estimates are used will be referred to as ‘background processes’1. The more foreground processes are included in a specific LCA study, the more ‘detailed’ the LCA will be


The more foreground processes are included in a specific LCA study, the more ‘detailed’ the LCA will be. Impact assessment based on a tailor-made factor approach is so straightforward, except for factors and methods that are lacking, that the duration and cost of the LCA study will not be significantly affected. There are two other issues which are not mentioned by Christiansen et al. (1997) and Todd et al. (1999) but which are likely to co-determine the amount of time and resources spent on an LCA study: procedures, e.g. a critical review; reporting, e.g. the frequency of interim reporting and the level of detail of these reports. In this Guide, from this point onwards individual sets of guidelines will be developed for two levels of sophistication, acknowledging that more than two levels might, of course, be distinguished here2


Detailed LCA: an LCA based on practical guidelines complying with ISO standards, where time and resource constraints do not play a dominant role; detailed LCAs are based on the assumptions and simplifications described in Section 1.2.2.3. Simplified LCA: an LCA based on practical guidelines not fully complying with ISO standards, e.g. standards on data collection, data quality requirements, data validation and allocation, for reasons associated with time and resource constraints; the simplified level has been introduced to provide a basis for performing faster and cheaper LCAs than detailed LCAs. For detailed LCA there are also options for extension. Options for extension: options for extending a detailed LCA to include, for example, new but not yet fully operational technologies (i.e


For detailed LCA there are also options for extension. Options for extension: options for extending a detailed LCA to include, for example, new but not yet fully operational technologies (i.e. sensitivity analyses on these), elaboration of new impact categories, development of new characterisation and normalisation methods and/or calculation of associated factors, partial uncertainty analyses and so on. Note that applying these options for extension implies a deviation from the assumptions and simplifications described in Section 1.2.2.3 and from the practical points of departure of each LCA phase, as described in Part 2a. There is no specific set of guidelines for extended LCA, as there is for simplified and detailed LCA, but certain additional guidelines or suggestions are here provided for extending several individual steps of a detailed LCA3. Note that the definitions used in this report differ from those of Christiansen et al. (1997) and Todd et al. (1999)


Note that the definitions used in this report differ from those of Christiansen et al. (1997) and Todd et al. (1999). This is because streamlined and simplified LCA as defined by these respective authors are not so much methods as procedures or applications of LCA. In this Guide we have aimed to develop different sets of methodological guidelines for these different types of LCA. The definitions have therefore been adapted somewhat. 1 These pragmatic definitions deviate from other definitions such as those in the report of the SETAC Working Group on Inventory enhancement (Clift et al., 1998). 2 Simplified LCA and detailed LCA with extensions are considered here to be reasonable extremes of the possible range of quantitative LCAs. Of course, further simplification is possible, e.g. a qualitative scanning LCA (used in some ecolabeling programmes) as well as further sophistication, e.g. an LCA study in combination with a Risk Assessment study


a qualitative scanning LCA (used in some ecolabeling programmes) as well as further sophistication, e.g. an LCA study in combination with a Risk Assessment study. These levels of LCA levels are not addressed here further, however. 3 According to Christiansen et al. (1997), it is not possible to formulate specific guidelines for simplified LCA that are applicable to all types of product systems. Although this may be true, we deem it feasible to develop generic guidelines, which need to be elaborated further in each LCA study, on how to simplify certain methodological elements.


Part 3 : Scientific background For the six decision situations distinguished in Section 2.2, we make the following recommendations with respect to the preferred level of sophistication: Table 2.3.1 : Recommended level of sophistication for six different decision situations. Global exploration of options Company-internal innovation Sector-wide innovation Strategic planning Test/comparison Comparative assertion disclosed to the public simplified X X X X detailed X X X X extended X As well as steering the procedural part of a study (see Section 1.3 of this Part of the Guide and Part 1 and 2a), because it will largely determine the appropriate level of sophistication, the decision situation may also be of decisive influence on the methodological choices made within an LCA study. Clearly, Scope definition is a crucial step that has major technical and procedural consequences


Clearly, Scope definition is a crucial step that has major technical and procedural consequences. Decisions taken during this step will have a huge bearing on the significance of the LCA results and it is therefore important to reflect accordingly on the issues for Interpretation. Whether the question to be answered by the LCA is related to Occasional, Structural or Strategic Choices is of major importance for the choices of models and data later on in the study (see Chapter 1 and Section 2.3 of this chapter). The model used and the data selected should reflect the strategic scope of the decision the LCA is intended to support. As starting points for this Guide, a number of simplifications have been made with respect to time (in model relations and in the specification of inventory results), geographical aspects (e.g. location of processes and impacts) and extent of the mechanisms included (e.g


location of processes and impacts) and extent of the mechanisms included (e.g. fixed input/output relations, technical production function, market and social mechanisms). If these simplifications would put severe constraints on the validity of the study results, they should be reconsidered and if possible adjusted. Thus, it should for example be validated whether spatial information can justifiably be excluded from the study. It should be duly validated whether temporal, geographical and technology coverage and coverage of economic processes, environmental interventions and impact categories are consistent with and sufficiently comprehensive in relation to the goal(s) defined. The main check to be made with respect to coverage of economic processes is whether phases or subsystems can justifiably be omitted in relation to the overall goal of the study


The main check to be made with respect to coverage of economic processes is whether phases or subsystems can justifiably be omitted in relation to the overall goal of the study. Furthermore, it should be checked whether the impact categories and environmental interventions selected are the relevant ones for the (product) systems studied and whether they are in line with the goal of the study. For six decision situations, we provide recommendations above on the most appropriate level of LCA sophistication (simplified, detailed, detailed and extensions). These decision situations are defined in broad terms and which of them matches the specific goal of the intended LCA study most closely should be duly examined. If it is opted to deviate from the recommended level of sophistication, sound reasons should be given for doing so


If it is opted to deviate from the recommended level of sophistication, sound reasons should be given for doing so. For example, a simplified LCA approach should not be chosen in an LCA study geared to a comparative assertion unless it is explicitly defined as a preliminary study to a detailed one, with the latter designed to support the comparative assertion in question. For Goal and Scope definition Lindfors et al. (1995a) list the following reporting issues: Co-functions excluded from the analysis by use of partitioning (allocation) should be reported. Final system boundaries shall be justified in relation to the goal of the study. Temporal boundaries for impacts should be given and justified. The final choice of impact categories, level of assessment and omitted categories and flows shall be reported according to the classification list given in this guideline [in this Guide, see Section 4.2]. Maximum base-line data quality requirements should be justified


Maximum base-line data quality requirements should be justified. Any deviation from initial plans may be reported. Any other limitations or assumptions of relevance to the results of the study shall be reported. Meier et al., 1997 give the following reporting guidelines for the scope phase: The boundaries, methodology, data categories and assumptions should be clearly stated and understandable. The scope of the study should be defined in sufficient detail to enable the study to address the stated objectives including stages of the life cycle, system boundaries, methodology, data requirements and assumptions. Data quality goals and any variability of data considered in the study should be clearly established and detailed.


Part 3: Scientific background The methodology used should be clearly and transparently stated and any differences in methodology from a full LCA should be explained. All assumptions and value judgements should be clearly detailed along with the justification for the assumptions. These authors also provide these reporting guidelines in the form of a practitioner’s checklist. PROSPECTS The discussion on descriptive and change-oriented (retrospective – prospective) analysis is still continuing and it is expected that this will give rise to new ideas in the nearer and more distant future. No specific developments are foreseen in the other areas. CONCLUSIONS Two elements can be distinguished with respect to the Scope of the study: 1. 2


No specific developments are foreseen in the other areas. CONCLUSIONS Two elements can be distinguished with respect to the Scope of the study: 1. 2. the main characteristics of the study, including temporal, geographical and technology coverage, coverage of economic processes, coverage of environmental interventions and impact categories, mode of analysis and level of sophistication of the study; and reporting, resulting in a Goal and Scope Report. The step Scope definition deals only with the main characteristics of the intended LCA study. Issues to be covered by a Goal and Scope Report are discussed elsewhere


With respect to these main characteristics of an LCA the following recommendations are made: temporal coverage specify base year or period according to ISO 14041 geographical coverage specify geographical area according to ISO 14041 technology coverage specify technology coverage according to ISO 14041; take current state-of-the-art technology as the baseline coverage of economic processes include all economic processes; narrow the number of economic processes included in cradle-to-gate, gate-to-gate or a difference analysis coverage of environmental interventions and impact categories include all impact categories for which practical methods are available and all environmental interventions for which characterisation factors are available, unless the scope is explicitly narrowed to a few environmental interventions and/or impact categories; include remaining impact categories and interventions qualitatively as far as possible (‘flags’) mode of analysis change-oriented analysis for


environmental interventions and/or impact categories; include remaining impact categories and interventions qualitatively as far as possible (‘flags’) mode of analysis change-oriented analysis for structural decisions level of sophistication distinction between detailed, simplified and options for extensions RESEARCH RECOMMENDATIONS No research recommended.


Part 3 : Scientific background 2.4 Function, functional unit, alternatives and reference flows TOPIC In this step the function, functional unit, alternatives and reference flows are defined. The functional unit describes the primary function(s) fulfilled by a (product) system, and indicates how much of this function is to be considered in the intended LCA study. It will be used as a basis for selecting one or more alternative (product) systems that might provide these function(s). The functional unit enables different systems to be treated as functionally equivalent and allows reference flows to be determined for each of them. DEVELOPMENTS IN THE LAST DECADE Heijungs et al. (1992) In Heijungs et al. (1992) this topic was treated under the heading “Defining the subject of the study” (section 1.3 of 1992 Guide)


DEVELOPMENTS IN THE LAST DECADE Heijungs et al. (1992) In Heijungs et al. (1992) this topic was treated under the heading “Defining the subject of the study” (section 1.3 of 1992 Guide). It was stated there that quantitative terms can be included in the process tree once a functional unit has been selected, implying that quantification of the reference flow was considered to be part of the Inventory analysis. The selection of the (product) systems to be compared and considered equivalent on the basis of the functional unit defined, was also an explicit element of the step “Defining the subject of the study” in Heijungs et al. (1992). ISO 14041 (1998E), clause 5.3.2 states the following with regard to the topic of function and functional unit (see textbox): In defining the scope of an LCA study, a clear statement on the specification of the functions (performance characteristics) of the product shall be made. The functional unit defines the quantification of these identified functions


The functional unit defines the quantification of these identified functions. The functional unit shall be consistent with the goal and scope of the study. One of the primary purposes of a functional unit is to provide a reference to which the input and output data can be normalised (in a mathematical sense). Therefore the functional unit shall be clearly defined and measurable. Having defined the functional unit, the amount of product, which is necessary to fulfil the function, shall be quantified. The result of this quantification is the reference flow. The reference flow is then used to calculate the input and outputs of the system. Comparisons between systems shall be done on the basis of the same function, quantified by the same functional unit in the form of their reference flows. If additional functions of any of the systems are not taken into account in the comparison of functional units, then these omissions shall be documented


If additional functions of any of the systems are not taken into account in the comparison of functional units, then these omissions shall be documented. For example, systems A and B perform functions x and y which are represented by the selected functional unit, but system A also performs function z which is not represented in the functional unit. It shall then be documented that function z is excluded from this functional unit. As an alternative, systems associated with the delivery of function z may be added to the boundary of system B to make the systems more comparable. In these cases, the processes selected shall be documented and justified. Source: ISO 14041, 1998E. Based on these ISO 14041 requirements, the following steps are distinguished in ISO/TR 14049 (1998) for defining a functional unit and determining the reference flows: identification of functions; selection of one or more functions as the relevant one(s); defining the functional unit; determining the reference flow


Below these four steps are described, based largely on ISO/TR 14049 (1998). Identification of functions In this step the purpose served by the product system, i.e. its function or functions, is identified. The starting point for this procedure may be a specific product to be studied (e.g. wall paint) or it may be the final need or goal, which may sometimes be fulfilled by several distinct products (e.g. wall decoration, which may be fulfilled by both paint and wallpaper or a combination of these). The functions are related to specific product (e.g. packaging) or process properties (e.g. transport), each of which may:


Part 3: Scientific background fulfil specific needs and thereby have a use value, which typically creates economic value to the supplier of the product, affect the functioning of other economic systems (e.g. wallpaper may have a - small - insulation effect, thus affecting the heat requirements of the building). Selection of function(s) In this step the relevant functions are selected, on the basis of which a functional unit will be defined and equivalent (product) systems selected in the case of a comparative study. The functions identified in the first step need not all be relevant for a particular LCA study. Thus, out of all the possible functions those that are relevant must be identified. For a solid interior wall, for example, surface protection may be unnecessary, while colouring is a relevant function of paint. See the textbox for more examples


For a solid interior wall, for example, surface protection may be unnecessary, while colouring is a relevant function of paint. See the textbox for more examples. The result of this step will determine which system alternatives will have to be taken into account and which not in the specific LCA study. In a comparative study, particular care will therefore have to be taken to ensure that any additional functions of each alternative are duly identified and described, and that all relevant functions are taken into account. Beverage packaging Beverage bottles have a packaging and an image function. The latter might also be relevant to take into account in some cases. Leaving out the image function of the packaging may lead to comparison of packagings that are technically similar (i.e. containing the same volume of beverage) but which the producer or customer will not accept as comparable. Hand drying Hand drying systems have a drying and a hygienic function


containing the same volume of beverage) but which the producer or customer will not accept as comparable. Hand drying Hand drying systems have a drying and a hygienic function. Both may be relevant to take into account. Leaving out the hygienic function may be regarded as unacceptable, e.g. in the food industry, where the bacteriaremoving ability of paper towels may be regarded as such an advantage that a comparison to electrical hand drying systems may not even be considered. Source: ISO/TR 14049 (1998). If a system fulfils just one specific function, the selection of function(s) step wilt be fairly straightforward. However, systems often fulfil more than one function. For instance, the primary function of shampoos is to clean hair but other important functions may include aesthetic (hair brightness) or hygienic (dandruff) concerns, or communicative functions (just smell how I washed my hair for you). Udo de Haes et al


Udo de Haes et al. (1996) distinguished two kinds of multifunctionality: the product system is defined by its primary function (e.g. washing), and all other functions of the product are facultative (e.g. anti-dandruff function); the product system is intrinsically multifunctional, with even the simplest ‘design’ not being able to be reduced to one function (e.g. a food product, see below). Basically, they proposed two alternative solutions to this multifunctionality problem1: a) b) monofunctional approach: ‘only the primary function of the system is considered, with analysis restricted to (one or more) products fulfilling this function, regardless of any other functions they might fulfil; multifunctional approach: the primary as well as other functions of the system analysed are considered (e.g. normal shampoos, anti-dandruff shampoos etc.). In the mono-functional approach, more or less recommended as a baseline by Udo de Haes et al


normal shampoos, anti-dandruff shampoos etc.). In the mono-functional approach, more or less recommended as a baseline by Udo de Haes et al. (1996), only the predominant function of the product system is taken into account. In the multifunctional approach one can define the function as precisely as one wishes. However, the more strictly the functional unit is described, the fewer alternatives will be left to compare. The functional unit ‘watching TV for 1 hour’ may be specified to include more and more functions, as in ‘watching colour TV for 1 hour’, ‘watching large-screen colour TV for 1 hour’, ‘watching large-screen colour TV with remote control for 1 hour’, etc., until there are no product alternatives left to compare. There will generally be various options for drafting an accurate definition of the functional unit which at the same time covers a range of slightly different alternatives and no hard and fast rules can therefore be given on this point


ISO/TR 14049 (1998) states that “some functions may be so intimately linked that separation is not possible, e.g., the heat generation of a light bulb cannot be detached from its primary function lighting. In other situations, separations of two linked functions may be technically possible, but due to other aspects, the two separate functions may still not be regarded as comparable to the joint functions. An example of 1 Originally proposed for application of LCA in the EU’s ecolabeling programme, these two approaches have been adapted slightly by the authors of this Guide for use in general LCA applications.


Part 3 : Scientific background this is the combined freezer-refrigerator, which may or may not be compared to a freezer and separate refrigerator, depending on the acceptability of this choice to the consumer (the latter option will typically take up more space than a combined option with the same internal volumes)”. Lindfors et al. (1995a) state that the multifunctionality problem should be addressed by either “using a multifunctional basis [for comparison] or by allocation, i.e. partitioning of resources, emissions etc. between the primary function and co-functions not included in the analysis. This shifts the problem to the Inventory analysis, i.e. the allocation.“ The conclusion here is that the multifunctionality problem can be solved in several ways: 1. 2. 3


This shifts the problem to the Inventory analysis, i.e. the allocation.“ The conclusion here is that the multifunctionality problem can be solved in several ways: 1. 2. 3. Take into account the primary function only and neglect all other functions; Take into account the primary function and all, or a selected number of, additional functions; Allocate between the primary function and the additional functions not included in the analysis. There is no further rationale for preferring one or other of these options; the appropriate choice simply depends on the goal of the study. Allocation (option 3) can be applied if the functions can be physically separated, as in the case of, say, combined heat and power (co-generation) plant. If separation is not feasible or appropriate, the additional function(s) can be neglected (option 1) or added to the primary function (option 2)


If separation is not feasible or appropriate, the additional function(s) can be neglected (option 1) or added to the primary function (option 2). If the goal is to compare, say, the cleaning function of a shampoo and nothing else, option 1 should be chosen and all other functions neglected. If the goal is to compare both the cleaning and the anti-dandruff function, option 2 should be adopted and the additional (anti-dandruff) function included in the functional unit. In practice, a product system may fulfil numerous functions at the same time and these examples and options will therefore have to be juggled in such a way as to yield two (or more) primary functions, again permitting one either to allocate for the other functions (option 3) or neglect them (option 1). Whatever the case, it will be clear that the eventual choice is highly dependent on the goal of the study and that the choice made should be duly justified and reported


Whatever the case, it will be clear that the eventual choice is highly dependent on the goal of the study and that the choice made should be duly justified and reported. The procedural aspect of the ‘selection of function(s)’ step may be very important. A number of stakeholders may have to be explicitly involved in this step of the study, for otherwise the final results may encounter acceptance problems. For a further discussion of these procedural aspects, see Section 1.3. Definition of functional unit Subsequently, the relevant functions are quantified in the functional unit. There are two key issues here: unit and quantity. Unit definition is of course related to the function or goal of the study. Defining the functional unit in terms of mass, mass per surface area or mass per surface area for X years will give different units: respectively kg, and yr. Any combination of units is in fact possible, depending on the function defined


Any combination of units is in fact possible, depending on the function defined. See the textbox for examples from ISO/TR 14049 (1998) and Wegener Sleeswijk et al. (1996).


Part 3: Scientific background Wall colouring (ISO/TR 14049, 1998) For wall colouring, the functional unit will typically have to specify the area to be covered (e.g. the type of wall (especially regarding its absorption and binding properties), the ability of the paint to hide the underlying surface (e.g. 98% opacity), and its useful life (e.g. 5 years). In the case of multifunctional units, the different quantities are sometimes linked, e.g. a wall covering insulation material may be available with a pre-coloured surface, which makes colouring unnecessary, thus supplying both insulation and colouring. The functional unit might then be: wall covering with a thermal resistance of with a coloured surface of 98% opacity, not requiring any other colouring for 5 years". Wheat (Wegener Sleeswijk et al., 1996) An interesting discussion of units in relation to the goal of the study can be found in a methodology report on agricultural LCAs (Wegener Sleeswijk et al., 1996)


If two wheat cultivation methods are compared to assess which is the environmentally sounder, the functional unit might be expressed as kg of harvested wheat. However, if the aim of the comparison is to determine the most environmentally sound form of agriculture for a certain geographical area, a better functional unit might be ha.yr wheat cultivation. In the latter case the goal is not to achieve the most efficient form of ,production but the environmentally soundest use of agricultural soil per year in a given area. These two different goals result in different units. It is another question entirely, of course, whether LCA is at all useful for questions relating to spatial planning (see section 2.2 of this Part and see Part 1). Food LCAs (Wegener Sleeswijk et al., 1996) Wegener Sleeswijk et al. (1996) give a practical suggestion on how to deal with the multifunctionality problem in defining a functional unit in food LCAs


Food LCAs (Wegener Sleeswijk et al., 1996) Wegener Sleeswijk et al. (1996) give a practical suggestion on how to deal with the multifunctionality problem in defining a functional unit in food LCAs. They state that foodstuffs often fulfil more than one function. They are frequently a source of nutrition and a source of enjoyment at one and the same time. In establishing the functional unit of a product with more than one function, real substitution should form the basis for defining an “abstract multifunction”: one functional unit of one product alternative should constitute a real substitute for one functional unit of another product alternative. In a comparison of, say, Wiener schnitzel and steak, it is important to find out how much Wiener schnitzel a consumer would eat in practice as a substitute for a given quantity of steak


In a comparison of, say, Wiener schnitzel and steak, it is important to find out how much Wiener schnitzel a consumer would eat in practice as a substitute for a given quantity of steak. If, for example, it is found in practice that an average portion of steak weighs 100 grams and an average portion of Wiener schnitzel 150 grams, the obvious approach would be to compare a portion of steak (100 grams) with a portion of Wiener schnitzel (150 grams). If in practice meat purchase is based above all on mass, however, a comparison of 100 grams of steak with 100 grams of Wiener schnitzel is the more appropriate choice. The quantity refers to the amount of function or service analysed. Basically, any arbitrary quantity can be taken, since its meaning is only relative in a comparative LCA. For reasons of Interpretation, it may be attractive to make its meaning absolute, e.g. annual (or annual individual) demand for a certain function in the Netherlands1


For reasons of Interpretation, it may be attractive to make its meaning absolute, e.g. annual (or annual individual) demand for a certain function in the Netherlands1. It will be clear that in this case the function will first have to be defined in temporal terms. Lindfors et al. (1995a) and Wenzel et al. (1997) state that the durability or the life span of the product should be taken into consideration in relation to the quantity of function/service analysed. In other words, the duration of the function provided by the product system should be taken into account. They give the example of the life span of paint in relation to the time it should protect a specific area, which is comparable to the example of wall colouring in the textbox. If, in the selection of function(s), more than one function has been selected as being relevant for the comparison in question, a multifunctional unit must be defined. The quantities of the different functions are sometimes linked, e.g


The quantities of the different functions are sometimes linked, e.g. a wall covering insulation material may be available with a pre-coloured surface, which makes colouring unnecessary, thus supplying both insulation and colouring. The functional unit might then be: wall covering with a thermal resistance of with a coloured surface of 98% opacity, not requiring any other colouring for 5 years’ (ISO/TR 14049, 1998). As noted in ISO/TR 14049 (1998), the equivalence of two products is in many cases determined by user acceptance. This acceptance, and thus whether two products are to be deemed comparable or not, may be influenced by the price of the alternatives and by the additional information given along with the products, e.g. information on their environmental performance


information on their environmental performance. Thus, for the purposes of product development or strategic management, it may be reasonable to compare two products not intuitively regarded as equivalent but assumed to be so under specific conditions of price and information. User satisfaction may also be determined by a complex of factors, as in the case of food. As this complex of factors is often hard to disentangle, pragmatic solutions are required, as suggested by Wegener Sleeswijk et al. (1996), for example; see textbox. 1 It should be noted however, that this absolute meaning is generally not valid for all preceding processes.


Part 3 : Scientific background Defining the reference flow Having defined a functional unit, the next task is to select alternative (product) systems that can provide this functional unit and quantify the performance of these systems using so-called reference flows. In comparative studies both tasks are relevant, while in non-comparative studies only the reference flow of the single (product) system studied need be established. ISO/TR 14049 (1998) does not explicitly discuss the selection of alternative product systems for analysis in a comparative LCA study. This is often a debating point in such studies, however, and the same frequently also holds for specification of certain key parameters of the reference flow or final product (e.g. trip rate, life span, mass and volume material specifications, etc.). Lindfors et al


trip rate, life span, mass and volume material specifications, etc.). Lindfors et al. (1995a) make an important addition to the ISO standards: in their view it should be mandatory to report not only the system alternatives studied, but also those not studied. As they say: “There might be other alternatives, which are not included in the study. To gain credibility it is important that relevant alternatives that are not studied are commented upon in the report. It is not necessary to list all product or service alternatives not covered by the study, but a minimum requirement is a comment that there are other alternatives and an explanation why these have not been considered.” Furthermore, they argue that “the choice of the reference alternative in comparative studies is a critical issue. An improper choice is obviously likely to give misleading results


An improper choice is obviously likely to give misleading results. Comparison of one product, based on up-to-date information, with a reference product, based on 5–10 years old literature data is a classic example.” Comparison of a new design with a reference product based on earlier technologies is similarly improper. In such cases it would be more appropriate to compare the new design to a ‘redesigned’ reference product, or at least to a reference product updated to up-to-date technology. It will be clear that the choice of the reference product will always affect the result of comparative studies. As Lindfors et al. (1995a) state, “it is important that this choice is made in such a way, that it is as representative as possible and that particularly the data qualities of compared alternatives are reasonably consistent.” System performance is quantified by means of a so-called reference flow, i.e


“a measure of the needed outputs from processes in a given product system required to fulfill the function expressed by the functional unit” (ISO 14041, 1998). The reference flow is the connecting flow between the physical output of a system and the amount of function delivered by that system as quantified in the functional unit. It is the flow upon which the whole LCA is based, for example the amount of detergent required (= reference flow) for washing a certain amount of clothes optically white (= functional unit)1. Lindfors et al. (1995a) argue that a “performance quality standard (if any), e.g. a certain level of corrosion protection provided by an industrial paint system” should be taken into account in quantifying the reference flow. This is supported by the work of Udo de Haes et al. (1996). In line with the proposal of Udo de Haes et al., three types of system performance can be distinguished: a) b) c) Standard performance refers to a known standard (national, e.g


(1996). In line with the proposal of Udo de Haes et al., three types of system performance can be distinguished: a) b) c) Standard performance refers to a known standard (national, e.g. DIN, or international, e.g. CEN), describing a standardised test applicable to all equivalent products: for example, the amount of detergent required to wash to a certain degree of cleanness a certain quantity of clothes with a certain degree of soiledness at temperature X, at Y degrees of hardness, etc. Recommended performance refers to manufacturers’ recommendations on product operating mode: for example, the detergent dosage indicated on the packaging. Actual performance refers to the actual performance which will often depend on the consumer behaviour, e.g. the average detergent dosage used by the consumer based on consumer studies. This actual performance can be taken as an average or as a range, which may a significant factor in the final LCA results


the average detergent dosage used by the consumer based on consumer studies. This actual performance can be taken as an average or as a range, which may a significant factor in the final LCA results. The latter might be used to provide environmental advice to consumers, etc. Several examples of reference flows are described In the textbox. 1 Note that the functional unit and reference flow are different quantities. On the basis of one functional unit, different reference flows will usually be quantified for each (product) system analysed. Only in exceptional cases will reference flows and functional unit be the same, but this will then generally limit the number of products that can be compared.


Part 3: Scientific background Paint Reference flows are typically expressed as the number of litres required for covering the surface area as defined by the functional unit. For example, in a standardised test, paint A may be determined to cover per litre, thus requiring 2.3 litres to cover the of the functional unit, provided the conditions in the standardised test are similar to those required by the functional unit (with regard to surface type and opacity). Hand-drying In a comparison of paper towels versus an electrical hand drier, it may be irrelevant to use a standardised test based on the technical properties of the paper such as mass, absorption power and tensile strength, if the actual weight of paper used depends on the dispenser design


A more appropriate measure would then be data collected by weighing the paper stock at the start and end of a suitable period in which the number of hands dried are determined by electronic surveillance of actual wash basins located in relevant institutions. Similarly, technical specifications of an electrical hand-drier, such as the volume of air and its temperature, may be irrelevant as a basis for calculating the reference function, if the actual running time of the device is determined by other factors, e.g. a built-in timer. Then, all that is needed is the running time and the electrical capacity of the equipment. Refrigerators For long-lived products, such as refrigerators with lifetimes of 10 or 20 years, technology development may be a factor that cannot be disregarded. One refrigerator with a lifetime of 20 years cannot simply be compared to two successive, present-day refrigerators with a lifetime of 10 years


One refrigerator with a lifetime of 20 years cannot simply be compared to two successive, present-day refrigerators with a lifetime of 10 years. The refrigerators available 10 years from now are certain to be more energy-efficient than current models; the energy efficiency of the second refrigerator in the 10+10 years option must be established by projecting trends, while that of the 20 years option is fixed. A comparison of refrigerators may be based on their internal and/or external volume. Although the primary function is obviously related to the internal volume, the external volume may a determining factor if the refrigerator is to be fitted in an existing kitchen. If an identical external volume is demanded, the internal volume may differ because of differences in insulation thickness. This can only be adjusted for by assuming differences in user behaviour (e.g


This can only be adjusted for by assuming differences in user behaviour (e.g. more frequent shopping trips, storage of certain items outside the refrigerator, adding another, smaller refrigerator elsewhere in the house). Each of these changes in behaviour will involve changes in different processes, which will then have to be included in the study. If, on the other hand, an identical internal volume is demanded, a change in insulation thickness may require adjustments in the physical surroundings of the refrigerator (the other kitchen furniture). If both the internal and external volume must be equal, there is obviously no adjustment feasible to accommodate the change in insulation thickness. As this demonstrates, the choice of required functions also determines the possible alternatives to be included in the study


As this demonstrates, the choice of required functions also determines the possible alternatives to be included in the study. Beverage packaging 100,000 half-litre one-way bottles may technically fulfil the same function of protecting 50,000 litres of beverage as 125,000 0.4-litre returnable bottles with a reuse rate of 90%. For the consumer, however, the difference in volume may be indistinguishable. If the consumer takes ‘a bottle to be a bottle’, total consumption of the beverage will decrease when the returnable bottles are introduced. In this case, the packaging cannot be studied independent of its contents. In this example there should also be iteration back to the “selection of relevant function(s)” step, or, alternatively, the goal of the study should be redefined, allowing for a comparison of beverage plus packaging taking into account the changes in consumption. Source: ISO/TR 14049 (1998). For even more examples see also ISO/TR 14049 (1998)


Source: ISO/TR 14049 (1998). For even more examples see also ISO/TR 14049 (1998). In the case of a multifunctional unit, the reference flows must be quantified in such a way that they fulfil all the functions included in the functional unit. This may imply that, although one of the functions can already be fulfilled using smaller amounts of the reference flow, the amount of reference flow has to be further increased to fulfil the other functions. If this is not acceptable, to the commissioning or interested parties, for example, the multifunctional problem should be solved by allocation (including system expansion) rather than by including the extra functions in the functional unit. Although the examples and phrasing of ISO/TR 14049 certainly provide a degree of insight, they still do not pin down precisely what a reference flow is or how it relates to a functional unit. Let us therefore expand and focus the discussion a little more


Let us therefore expand and focus the discussion a little more. Consider a comparison of two systems for lighting a room with the same amount of light: an incandescent lamp and a fluorescent lamp. Suppose we have defined the functional unit as lighting a standard room for 1 year with a certain flux of light. The flow diagrams of the two product alternatives then contain the two use processes as follows (see Figure 2.4.1).


Part 3 : Scientific background Following the ISO examples, the reference flows would be 3 incandescent lamps for the first system and 2 fluorescent lamps for the second. However, lamps are only one of the input flows to the respective use processes, electricity being the other. It might therefore equally well be argued that the reference flow for the first system is 200 kWh of electricity, for the second 100 kWh. Or one could say there is a set of reference flows for each system. Another complication in this ISO-based procedure is that assignment of these numbers (3 incandescent lamps, 2 fluorescent lamps, etc.) depends on how the process data are specified and is therefore part of the Inventory analysis; thus, it cannot take place in the prior Goal and scope definition step. In this Guide the concept of reference flow has therefore been adapted somewhat. The use processes and quantified flows are specified in the Inventory analysis


In this Guide the concept of reference flow has therefore been adapted somewhat. The use processes and quantified flows are specified in the Inventory analysis. Goal and scope definition is concerned with a different issue: in this case, the specification that 1000 hours of light with an incandescent lamp are to be compared with 1000 hours of light with a fluorescent lamp. These two items then constitute the reference flows for the two systems. They form two alternative ways of supplying the functional unit (1000 hours of light). These alternatives, and thus these two reference flows, may be referred to as ‘products’ in the generalised sense in which a barber or teacher supplies a product. In this sense, ISO's definition of a reference flow ("the amount of product which is necessary to fulfill the function")1 can even be retained. 1 Note that this definition of reference flow, on p. 5 of ISO 14041 (1998), differs from the definition on p. 2 of the same document.


Part 3: Scientific background Summarising, reference flows are product-specific flows having the functional unit as a common denominator: reference flow for system 1: 1000 hours of light with an incandescent lamp; reference flow for system 2: 1000 hours of light with a fluorescent lamp; functional unit: 1000 hours of light; process data (3 incandescent lamps, 2 fluorescent lamps, 200 kWh electricity, etc.): to be specified in the step ‘Data collection and relating data to unit processes’, in the Inventory analysis phase. One interesting advantage of this modification is that it allows behavioural differences between the alternative systems to be explicitly incorporated in the specification of the reference flows. Tube lights, for instance, tend to be switched off less frequently than other lamps


Tube lights, for instance, tend to be switched off less frequently than other lamps. The function ‘lighting a kitchen for 365 evenings’ may then well involve 3000 hours of tube light versus 1000 hours of light with a different lamp, with subsequent explicit consequences for the reference flows. The consequences further on in the Inventory analysis relate to well-defined flows for different amounts of light and electricity. Based on the above reasoning we come to the following definitions for the functional unit and the reference flow (adapted from ISO 14040): Functional unit: quantified service provided by the product system(s) under study for use as a reference basis in a life cycle assessment study. Reference flow: quantified flow generally associated with the use phase of a product system and representing one way (i.e. by a specific product alternative) of obtaining the functional unit


Reference flow: quantified flow generally associated with the use phase of a product system and representing one way (i.e. by a specific product alternative) of obtaining the functional unit. Given these adapted definitions, the discussion on actual, recommended and standard performance (and related issues) is an issue connected with the step ‘Data collection and relating data to unit processes’, in the Inventory analysis. Guidelines on this subject are therefore given in Part 2a, Section 3.3.6. With respect to reporting, Lindfors et al. (1995a) list the following issues for the step Function, functional unit, alternatives and reference flows: The main user function(s) forming the basis for the LCA shall be clearly defined and reported. The functional unit(s) of the studied system(s) shall properly describe the services provided and be clearly defined and reported. A brief description of the product group under study (functions) is recommended


A brief description of the product group under study (functions) is recommended. The studied product or service alternatives shall be described and the choice justified. Relevant alternatives not covered by the study should be commented upon or listed in the report. If no relevant alternative exists, it is equally important to make such a statement. Meier et al. (1997) give the following reporting guideline: The functional unit of the system under study should be unambiguously defined and should reflect the actual function of the system in a measurable and quantitative way. The functional unit should be relevant to the goal of the study. PROSPECTS No specific developments are foreseen in this area. CONCLUSIONS Concluding, we recommend following the stepwise structure proposed in ISO/TR 14049 (1998) with a minor addition: Identification of functions identify all relevant functions of the product systems studied


Selection of one or more functions as relevant select one or more functions as the relevant functions for comparison; if more than one function is relevant: take into account the primary function only and neglect all other functions, or take into account the primary function and (all) the additional functions, or allocate between the primary function and the additional functions, selecting the appropriate option for the particular goal of the study.


Part 3 : Scientific background Defining the functional unit specify selected function(s) in relevant SI or SI-derived units; determine an arbitrary or absolute (e.g. annual) quantity. Determining equivalent alternative (product) systems and reference flows determine and specify the alternative systems studied in terms of the key parameters of the reference flow (e.g. trip rate, life span, mass and volume material specifications, etc). All four steps are relevant for comparative studies and comparative assertions. In non-comparative studies the first step is optional and may be omitted, since only one system is then considered regardless of the functions it fulfils. RESEARCH RECOMMENDATIONS Short-term research How to deal with the divergence between standard, recommended and actual use. Long-term research Incorporating monetarily defined functional units in the LCA framework. Describing ‘lifestyles’ in terms of operational functional units.


Part 3: Scientific background 3. Inventory analysis 3.1 General introduction In the Goal and scope definition phase of an LCA the basic groundplan for the study is established, as discussed in Chapter 2. The second phase of an LCA is the Inventory analysis (see Figure 3.1.1). According to ISO 14041 (1998E) this phase is concerned with “the collection of the data necessary to meet the goals of the defined study” and with the associated “data collection and calculation procedures” and “is essentially an inventory of input/output data with respect to the system being studied.” The aim is thus to prepare an inventory, first qualitative then quantitative,of all the processes involved in the life cycle of the product (or function) system(s) under study (herafter: ‘product system’), detailing all relevant interactions with the environment. The Inventory analysis is generally the most time and resource consuming phase of an LCA


The Inventory analysis is generally the most time and resource consuming phase of an LCA. The product system, defined by ISO 14041 (1998E) as “a collection of unit processes connected by flows of intermediate products which performs one or more defined functions”, affects the environment via environmental interventions such as resource extractions or emissions of hazardous substances. The basic element of the Inventory analysis is thus the unit process. The term unit process refers to any kind of activity producing an economically valuable output such as steel, electricity or bread, or providing an economically valuable service such as transport or waste management. Products, services or resources, etc. are converted into other products, services and emissions. Every product and service used is fed by


Part 3 : Scientific background other unit processes and every product and service produced (particularly waste to be processed) feeds in to other processes.1 These supply and consumption processes are by definition included as part of the product system when the complete life cycle is considered. Proceeding from the reference flow specified in the goal and scope phase (see Figure 2.4.1), upstream and downstream unit processes are identified based on the economic in- and outflows of a process. The first process is usually a use-related process, e.g. use of a refrigerator, watching television, etc. The processes collected in this way together constitute the life cycle of the product system investigated. If more product systems are studied in a given study, these operations are repeated for each system. The processes in the life cycle can be arranged in the form of a flow diagram. A flow diagram is a systematic arrangement of the main processes which make up the product system


The processes in the life cycle can be arranged in the form of a flow diagram. A flow diagram is a systematic arrangement of the main processes which make up the product system. In drawing the flow diagram, first the boundary between the product system and the environment system needs to be determined. For example, it has to be decided whether landfill and agricultural production are to be included as unit processes within the system boundary. Next, the characteristics and data of each process included in the flow diagram have to be determined. Some processes and their characteristics are available in publicly accessible databases or literature. Nevertheless, many data will have to be collected in dedicated literature studies. Process modeling (e.g. process engineering models) may also be useful. Particular attention should be given to the quality of the data collected, by comparison with data from other, similar sources and by compiling mass and energy balances, for example


Particular attention should be given to the quality of the data collected, by comparison with data from other, similar sources and by compiling mass and energy balances, for example. Next, the problem of processes supplying multiple functions needs to be addressed. The production of chlorine, sodium hydroxide and hydrogen by electrolysis of common salt is an example of a multiple process. Since these products are produced in fixed quantities and since product systems do not generally need both products, at least not precisely in the fixed quantities, an allocation step is required. In this allocation step the multiple process is often divided into two or more single processes, purely for analytical purposes. Finally, the quantity of each single function required by the product system is calculated for each single process


Finally, the quantity of each single function required by the product system is calculated for each single process. All products and materials are balanced by multiplying each process by the appropriate number: the volume produced is exactly that required in the subsequent process and all that remains at a systems level is a service which is provided externally, that is, the functional unit. Their aggregation across all the processes produces the inventory table. The general operating procedure for the Inventory analysis as briefly introduced above is the one generally encountered in LCA software programs. To be complete, however, the Inventory analysis should include a number of additional steps, among them preparatory steps, to be performed before any data is entered or software calculations made, and several steps relating to procedures, reporting and other ‘miscellaneous’ issues


As elaborated in this Guide, the Inventory analysis therefore distinguishes ten steps (see Section 1.4): Procedures (no special section in this Part; see Chapter 1); Compilation of flow diagram and process data Economy - environment system boundary (Section 3.2, p. 479); Flow diagram (Section 3.3, p. 483); Format and data categories (Section 3.4, p. 485); Data quality (Section 3.5, p. 491); Data collection and relating data to unit processes (Section 3.6, p. 495); Data validation (Section 3.7, p. 499); Cut-off (Section 3.8, p. 500); Allocation Multifunctionality and allocation (Section 3.9, p. 505); Calculation of inventory results Calculation method (Section 3.10, p. 522). Further points of departure in elaborating these Inventory analysis steps are ISO documents 14040 (1997E) and particularly ISO 14041 (1998E) with respect to the methodological framework and the issues for Inventory analysis proposed there


Below, the ISO proposals are further operationalised, taking into account the work of the SETAC Working Group on Inventory enhancement (Clift et al., 1998) and relevant proposals by other authors. Deviations from ISO arise only if there are significant reasons for doing so. All steps distinguished above will be discussed according to a fixed format: ‘Topic’, ‘Developments in the last decade’, ‘Prospects’, ‘Conclusions’ and ‘Research recommendations’. As explained in Section 1.5 1 For brevity and readability, we shall often write ‘process’ instead of ‘unit process’.


Part 3: Scientific background the step dealing with procedures is not discussed separately in this chapter, but in integrated fashion, for all phases, in Section 1.3. It should be noted once again that our focus here is the change-oriented type of LCA. Moreover, the steps elaborated below assume a number of simplifications in the modeling set-up, as discussed earlier in Section 1.2 of this Part of the Guide. The key simplifications introduced are: use of linear relations and exclusion of most economic, socio-cultural and technological mechanisms. Thus, fixed input/output relations and a ‘technical’ production function are employed. In this sense the inventory model specified here is a mechanical one. 3.2 Economy - environment system boundary TOPIC In LCA each and every flow should be followed until its economic inputs and outputs have all been translated into environmental interventions


3.2 Economy - environment system boundary TOPIC In LCA each and every flow should be followed until its economic inputs and outputs have all been translated into environmental interventions. The term ‘environmental interventions’ refers to flows entering the (product) system (natural resources, for example, but also land use) which have been drawn from the environment without prior human transformation, or flows of materials leaving the (product) system which are discarded into the environment without subsequent human transformation (Figure 3.2.1). Environmental interventions are thus flows crossing the boundary between the economy (= product system) and the environment. To create a clear distinction between the product system and the environment and between elementary and other flows, the economy-environment boundary should be explicitly defined. Whenever a system is studied, system boundaries are needed to separate the system from the rest of the world


Whenever a system is studied, system boundaries are needed to separate the system from the rest of the world. In LCA Inventory analysis three types of boundaries can be distinguished (Heijungs et al., 1992): 1. 2. 3. the boundary between the product system and the environment system; the boundary between processes that are relevant and irrelevant to the product system (cut-off); the boundary between the product system under consideration and other product systems (allocation). The first of these will be discussed here, the second under the heading ‘Cut-off and data estimation’ (Section 3.8) and the third under the heading ‘Multifunctionality and allocation’ (Section 3.9). Although some boundaries of the first type are very clear, there are major areas of ambiguity with regard to the boundary between the product and environment system, as is illustrated by the cases of landfill sites and agricultural soil. These issues of ambiguity will be examined below


These issues of ambiguity will be examined below. DEVELOPMENTS IN THE LAST DECADE The issue of system boundary definition is treated in two different sections of ISO 14041: in ‘Scope of the study’: 5.3.3 Initial System boundaries, as part of the Goal and scope definition; in ‘Calculation procedures’: 6.4.5 Refining the system boundaries, as part of the Inventory analysis.


Part 3 : Scientific background The definition of the boundary between the product system and the environment system is Heijungs et al. (1992) The system boundary between the product system and the environment system is explicitly mentioned in the 1992 guide (pp. 27–28): a distinction is made between economic and environmental processes. It is stated that almost any activity incurring costs is an economic process; treatment steps occurring after a substance has been introduced into the environment (e.g. purification of river water to produce drinking water) should not be included in the product system causing the emission; landfilling of waste is to be considered an economic process; processes relating to agriculture, livestock management, forestry, etc. are to be considered economic processes; in processes involving personnel, consideration might be given to including additional physiological and economic processes (increased metabolism, eating and drinking, commuting etc.)


implied in the statement “Ideally, the product system should be modeled in such a manner that inputs and outputs at [its] boundary are elementary flows” (Section 5.3.3). An elementary flow is defined in ISO 14040 (1997E) as “material or energy entering the system being studied, which has been drawn from the environment without previous human transformation; material or energy leaving the system being studied, which is discarded into the environment without subsequent human transformation”. ISO thus makes an explicit statement here as to how this boundary should be defined; the key distinction is “human transformation”. In defining the product system-environment boundary there is no consideration for the ‘grey’ area ambiguity, however, with questions such as “does the agricultural topsoil belong to the environment or to the product system studied” remaining unanswered