The problem comes up after data collection, when it turns out that production processes for some inflows and waste treatment processes for some outflows are unknown or undocumented. 1 In the cut-off discussion, the term “flows” refers specifically to all economic input flows and the output flow “waste to be treated”. 2 One important additional situation in which a cut-off may be introduced is a difference analysis (see Section 2.3.3). Part 2a: Guide


Cut-off is interpreted as more than simply ignoring certain parts. More importantly, the estimation of lacking data is an essential element in this Guide. Cut-off comprises two distinct aspects: dealing with missing unit processes and dealing with missing interventions from the unit processes included. Guidelines Guidelines for simplified LCA In a difference analysis (see Section 2.3.3), cut-off of flows that are qualitatively and quantitatively identical across the various alternative product systems considered may provide an attractive shortcut. Try to avoid cut-off as much as possible. Several estimation procedures are available for this purpose; see under Guidelines for detailed LCA and optional extensions below. In practice, however, time and budget will not allow the application of these estimation procedures for most of the data gaps. Cut-off will then be achieved by putting flows explicitly to zero

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


In practice, however, time and budget will not allow the application of these estimation procedures for most of the data gaps. Cut-off will then be achieved by putting flows explicitly to zero. Guidelines for detailed LCA and optional extensions In a difference analysis (see Section 2.3.3), cut-off of flows that are qualitatively and quantitatively identical across the various alternative product systems considered may provide an attractive shortcut. Avoid cut-offs as much as possible by collecting process-specific data


Avoid cut-offs as much as possible by collecting process-specific data. If this is not possible, estimations must, whenever reasonably possible, be made of the significance for the remainder of processes for which specific data cannot be found by environmental input-output analysis at the sectoral level1 (see Part 2b, Section 3.8); approximation of the process by a similar process (for instance estimating HDPE production by LDPE production); comparing the flow for which data are lacking with a reasonably similar flow for which data are known (see Part 2b, Section 3.8), and justify whether cutting off is reasonable or whether specific process data should be gathered after all. If estimation is not possible, try to estimate the potential quantitative and qualitative significance of the flow for which specific data are lacking


If estimation is not possible, try to estimate the potential quantitative and qualitative significance of the flow for which specific data are lacking. If all of the above options are not feasible, cut off only those flows for which data are lacking, by putting them to zero, and report these flows clearly (see also Section 4.3.3.18). After each of the above-mentioned estimation steps, it should be decided – and the decision should be justified – whether or not the estimations give cause for additional collection of specific process data after all


Report: criteria for initial inclusion of inputs and outputs; description of criteria and assumptions used for estimating or ignoring missing flows; estimated effect of estimation or omission on the results; in the case of a comparative assertion: analysis of material flows to justify their inclusion or exclusion in a comparative context; sensitivity analysis to refine the system boundaries; omissions of life cycle stages, processes or economic and/or environmental flows; estimated process data along with primary and secondary process data, indicating clearly which data items have been estimated, and which estimation principles have been used (in Section 3.3.6). 1 As noted in Parts 2b and 3, input-output analysis cannot be applied to the use and waste management phases. Part 2a: Guide


Example (hypothetical) “In the example system, several inputs and outputs are cut off. These cut-offs have not all been included, for the sake of clarity. As an example, the potential contributions of the refinery facility and a catalyst, e.g., platinum, are estimated by Input-Output Analysis. The analysis uses the MIET model (see Part 2b, Section 3.8). See the table below for results. resources crude oil emissions to air 1-butene benzene carbon dioxide dioxins (unspecified) ethylene nitrogen oxides sulphur dioxide emissions to water benzene cadmium lead mercury phenol catalyst chemicals 0.023 kg _ 0.054 kg — 0.00016 kg 0.00020 kg equipment 0.0034 kg _ 0.021 kg – In addition, cut-offs have been used for the input of lubricants for refining, the outputs of residue to dump from the incineration of chemical waste, and the output of used bags from the use process (packaging a loaf of bread)


Finally, the co-product of "recovered energy from incineration of chemical waste" has not been allocated, but just ignored for the sake of simplicity. This can be justified by acknowledging that the revenues from energy recovery are negligible compared to those of waste incineration.” 3.3.9 Multifunctionality and allocation Topic Most industrial processes are multifunctional. Their output generally comprises more than a single product, and raw material inputs often include intermediates or discarded products. LCA practitioners are thus faced with the problem that the product system or systems under study provide more functions than that which is investigated in the functional unit of interest. An appropriate decision must therefore be made as to which of the economic flows and environmental interventions associated with the product system under study are to be allocated to the functional unit produced by that system


Decisions on the specifics of allocation will obviously be determined by the precise nature of the system boundaries as previously defined (see Section 3.3.2), since these determine which inputs and outputs are to be regarded as associated with the function of interest. An appropriate allocation procedure is thus required to partition the inputs and outputs of all relevant processes to the appropriate product systems. Main choices Allocation is the result of the multifunctionality of one or more unit processes, and is performed at the unit process level. Part 2a: Guide


The use of data from allocated databases is to be restricted to simplified LCAs; for detailed LCAs, this is to be avoided as much as possible. The ISO preference order for dealing with allocation is more clearly specified with regard to the application of the different options in simplified and detailed LCAs and in possible extensions, with regard to more detailed modeling and actual allocation, and with regard to operational aspects. Co-production, combined waste treatment and recycling are treated on the basis of the same allocation principles. Guidelines Guidelines for simplified LCA If possible, avoid allocation by modeling within the Inventory analysis. Possible methods are the following, in order of preference. Use single-function (cradle-to-gate databases) as a basis, such as ETH or BUWAL (see Part 2b, Section 3.6 for references to these databases). In this case all multifunction processes are already allocated by the maker


In this case all multifunction processes are already allocated by the maker. Treat open-loop recycling as closed-loop recycling, using a quality factor indicating the lower value of the recycled material. Use existing physical-causal waste management models. If allocation cannot be avoided, possible allocation methods are: economic allocation based on the value of all resulting functions, where feasible (see Part 2b, Section 3.9.1); substitution with pre-allocated cradle-to-gate database data; allocation based on indicators of economic value, such as mass, volume, or energy content; quick and dirty last resort methods, based on very rough estimations, such as 5050%, prices of similar products etc., or allocating all flows to the function investigated. Justify and describe the methods used to avoid allocation and the methods used to allocate. Check the following issues and, where relevant, use them to make recommendations for further analysis in the Interpretation


Check the following issues and, where relevant, use them to make recommendations for further analysis in the Interpretation. Are any other simplified allocation keys possible? In the case of a comparison, are there important differences in the allocation situations between the various systems compared? A decision should be taken as to whether and how the influence of different allocation methods will be further analysed in the Interpretation phase. Guidelines for detailed LCA If possible, avoid allocation by modeling within the Inventory analysis. Possible methods are the following, in order of preference. Split up processes that are not really multiple. In practice, this means that more detailed process sheets or databases are consulted, or that more detailed measurements are made. Model long-term technical-physical relations in waste processing, in addition to existing models


Model long-term technical-physical relations in waste processing, in addition to existing models. If allocation cannot be avoided, allocate using economic allocation based on the market value or constructed market value of all the resulting functions (see Part 2b, Section 3.9.1). If the above-mentioned methods cannot be applied, use one of the possible methods for allocation mentioned under simplified LCA as a last resort. Part 2a: Guide


Justify and describe the methods used to avoid allocation and the methods used to allocate, giving special attention to the situations where a last resort method had to be used. Check the following issues. Are any other allocation keys possible? In the case of a comparison, are there major differences in the allocation situations between the various systems compared? The influence of the allocation methods used should be further analysed in the Interpretation phase in the form of a sensitivity analysis. If last resort methods have been applied, they must be given special attention in the sensitivity analysis in Section 5.3.6. Guidelines for optional extensions All guidelines provided above for detailed LCA apply here. In addition to the first guideline on avoiding allocation by means of modeling within the Inventory analysis, the following guideline is given. If relevant and possible, apply market analysis for main co-products (= system expansion) to avoid allocation


If relevant and possible, apply market analysis for main co-products (= system expansion) to avoid allocation. If relevant and possible, make a linear programming optimisation model for one main process to avoid allocation. We advise the LCA practitioner to do this only if (s)he is familiar with optimisation models (see the various papers by Azapagic and Clift referenced in Part 3 for more details). If relevant and possible, apply symmetrical substitution as an allocation method in addition to economic allocation (see Part 2b, Section 3.9.2) Example (hypothetical) “The refinery process is a multifunctional process. The allocation is based on sales (= quantity × price) of the products. The proceeds of the six products as produced by the installation are summarised in the table. The share of each product in total proceeds is the allocation factor for that product


The proceeds of the six products as produced by the installation are summarised in the table. The share of each product in total proceeds is the allocation factor for that product. product 1: fuel oil (good) 2: naphtha (good) 3: kerosene (good) 4: long residue “waste” (good) 5: food waste (service) 6: wood waste (service) Total quantity price 0.15 0.20 0.10 0.05 0.15 0.80 – proceeds allocation factor 0.25 0.30 0.05 0.03 0.10 0.27 1.00 Part 2a: Guide


The resulting six mono-functional processes are tabulated below. production of fuel oil production of naphtha production of kerosene production of long residue "waste" treatment of food waste treatment of wood waste economic outflows (kton) fuel oil naphtha kerosene long residue "waste" chemical waste 0.5 0.6 0.1 0.06 0.2 0.54 economic inflows (kton) food waste wood waste PE (ton) lubricants 0.0025 0.003 0.0005 0.0003 0.6 0.0001 0.0027 5.4 emissions to air (g) 7.2 1.2 9.6 0.72 2.4 6.5 emissions to water (g) Cd Hg benzene 0.07 0.7 8.4 0.084 0.84 1.4 0.014 0.14 0.84 0.0084 0.084 2.8 0.028 0.28 7.6 0.076 0.76 3.3.10 Calculation method Topic Collection of process data yields a database of processes. The act of quantitatively relating these processes to one another, scaled to the reference flow following from the functional unit, is referred to here as the calculation method


The act of quantitatively relating these processes to one another, scaled to the reference flow following from the functional unit, is referred to here as the calculation method. The calculation result is a set of linked and scaled processes, each with scaled environmental interventions, which are usually aggregated. Main choices Matrix-based calculations are preferred because they easily allow for recursive relationships. The calculation of inventory results includes an aggregation of all interventions over all unit processes, but there are also unaggregated results, which serve all types of purposes, like the contribution analysis (see Section 5.3.4) Guidelines Guidelines for simplified LCA For each alternative product system, calculate the inventory table by scaling all processes in relation to the reference flow of that product system. This means that, Part 2a: Guide


within each product system, each unit process should be scaled in such a way that it delivers the quantity of product or service that is necessary for the reference flow. Use software based on matrix inversion. If this is not possible, use other software. Document explicitly any software used for the calculation, if possible along with the calculation procedures involved. If the final calculation shows that the system delivers not only the desired functional unit but also another function or functions, further allocation must take place. Check which unit process delivers the “extra” function(s) and allocate this process (see Section 3.3.9). After this, recalculate the inventory table. Report the inventory table and all economic flows not followed to the system boundary together. It may be convenient to report the results for the different alternatives in one table. An example form for completion is provided in Part 2b, Section 3.10


It may be convenient to report the results for the different alternatives in one table. An example form for completion is provided in Part 2b, Section 3.10. Guidelines for detailed LCA and optional extensions Guidelines for simplified LCA also apply here, but the first guideline is replaced by the following set of guidelines. For each alternative product system, calculate the inventory table by scaling all processes in relation to the reference flow of that product system. This means that, within each product system, each unit process should be scaled in such a way that it yields the quantity of product or service that is necessary for the reference flow. Use software based on matrix inversion. If this is not possible, use other documented software, or specify the algorithm or algebra used for the calculations, and specify whether the outcomes are compatible with the outcomes of matrix inversion


Document explicitly any software used for the calculation, along with the calculation procedures involved. If a sequential1 calculation technique is applied: check whether there are any loops within the systems studied; in the case of a comparison, check whether the number of loops differs for the various product systems studied. Check how loops have been treated in the literature and in the reference databases used, and, in the case of a comparison, whether the number of loops differs for the background processes of the various product systems studied. If deficits are identified, these can be adjusted directly by using a different calculation method. If this is not possible for practical reasons, assess the influence that ignoring loops might have on each of the systems studied, by means of a sensitivity analysis in the Interpretation phase2


If this is not possible for practical reasons, assess the influence that ignoring loops might have on each of the systems studied, by means of a sensitivity analysis in the Interpretation phase2. 1 In a product system there may be internal loops, for instance when the extraction of coal requires electricity and the production of coal requires electricity. In a matrix method, the calculation takes this accurately into account, while in a sequential method, the solution is only an approximation, and the accuracy depends on the number of times the loop is passed. Depending on the software used, the number of passes may be one, a fixed number (e.g. 5), or it may depend on the size that each additional pass adds to the results. 2 This may be a qualitative sensitivity analysis for detailed LCA and a quantitative sensitivity analysis modeling the loops concerned, as an optional extension. Part 2a: Guide


Example (hypothetical) “In the example of PE bags, all processes have been scaled using a matrix-based algorithm. The scaling factors are as listed. unit process refining; allocated to fuel oil refining; allocated to naphtha extraction of oil incineration of chemical waste production of ethylene production of PE production of plastic bags production of electricity packaging a loaf scaling factor 8.1 0.0008 0.01 0.01 The interventions of each process have been scaled accordingly and aggregated over the entire system. This produces the following results


This produces the following results. intervention resources crude oil emissions to air 1-butene benzene carbon dioxide dioxins (unspecified) ethylene nitrogen oxides sulphur dioxide emissions to water benzene cadmium lead mercury phenol product system 8.1 kg 7.8E–7 kg 9.9E–7 kg 2.2 kg 8.1E–14 kg 1 .2E–4 kg 3.7E–3 kg 2.0E–2 kg 1 .2E–9 kg 4.4E–8 kg 3.0E–9 kg 2.8E–9 kg 2.4E–8 kg economic inflows not followed to the system boundary lubricants economic outflows boundary used plastic bags residue to dump recovered energy 2.4 kg not followed to the system 0.08 kg 0.0008 MJ Notice that these results exclude the estimates of the IOA.” 3.4 Results of Inventory analysis The main result of this phase, which is the input of the next phase – Impact assessment – is the inventory table; see above for an example. But of course, there is a host of additional information, like aspects that could not be quantified, information related to data quality, and so on


But of course, there is a host of additional information, like aspects that could not be quantified, information related to data quality, and so on. These other forms of information are especially useful in the Interpretation phase. Part 2a: Guide


Impact assessment Recipe Procedures Selection of impact categories Selection of characterisation methods: category indicators, characterisation models Depletion of abiotic resources Depletion of biotic resources Land competition Loss of biodiversity Loss of life support function Desiccation Climate change Stratospheric ozone Human toxicity Marine aquatic ecotoxicity Terrestrial ecotoxicity Freshwater sediment ecotoxicity Marine sediment ecotoxicity Photo-oxidant formation Acidification Eutrophication Waste heat Malodorous air Malodorous water Noise Impacts of ionising radiation Casualties Interventions for which characterisation factors are lacking Economic flows not followed to system boundary Classification Characterisation Normalisation Grouping Weighting Page Topic Life Cycle Impact Assessment (LCIA) is the phase in which the set of results of the Inventory analysis – mainly the inventory table – is further processed and interpreted in terms of environmental impacts and societal


Assessment (LCIA) is the phase in which the set of results of the Inventory analysis – mainly the inventory table – is further processed and interpreted in terms of environmental impacts and societal preferences


To this end, a list of impact categories is defined, and models for relating the environmental interventions to suitable category indicators for these impact categories are selected. The actual modeling results are calculated in the characterisation step, and an optional normalisation serves to indicate the share of the modeled results in a worldwide or regional total. Finally, the category indicator results can be grouped and weighted to include societal preferences of the various impact categories. Part 2a: Guide 4. 4.1


Starting points ISO 14042 has been the general starting point for this phase. The ISO requirements have subsequently been made operational through the work of the SETAC Working Group on Impact Assessment and many individual projects. The Impact assessment steps described in this Guide have been copied from ISO 14042, with a few adaptations. For a justification and explanation of these adaptations, see Part 3, chapter 1. The requirements of ISO 14042 have been closely followed, with the following additions or further specifications: The list of impact categories and best available models drawn up by the SETACEurope Working Group on Impact Assessment has been taken as the basis for the baseline impact categories and category indicators. In this method, the impact indicators focus on the so-called midpoints of the cause-effect chain, and the method is referred to below as the problem-oriented approach


In this method, the impact indicators focus on the so-called midpoints of the cause-effect chain, and the method is referred to below as the problem-oriented approach. Quality analysis has been implemented in the section on key issues for sensitivity analysis; the latter is conducted as part of the Interpretation. All additional main methodological choices, including references to all ISO steps, are addressed in the following sections on main choices; recipe steps are given, sometimes deviating from ISO 14042. Instead of the baseline Impact assessment approach, entirely different approaches towards Impact assessment could be chosen. Eco-indicator 99 provides such an approach, with partly different impact categories and category indicators. EPS is another example. Recipe 4.3.1 Procedures Topic Procedural organisation should involve a common treatment of all general and specific subjects that the parties involved wish to discuss in this Impact assessment phase


Recipe 4.3.1 Procedures Topic Procedural organisation should involve a common treatment of all general and specific subjects that the parties involved wish to discuss in this Impact assessment phase. Attention should be given to the following issues of this phase


Attention should be given to the following issues of this phase. The choice of impact categories to be taken into consideration (whether or not quantified) The choice (and/or development) and use of the characterisation method(s) The choice of process groups/substance groups to be taken apart from calculation and presentation The calculation of effect scores per impact category (including a validated software program) The presentation of the quantitative results of the Impact assessment per impact category An account of non-quantified but relevant environmental aspects The execution of the normalisation step The execution of the weighting step The execution of a sensitivity analysis The presentation of results, including marginal notes and possible (preliminary) conclusions Intentions with respect to the approach to be used in the following phases (especially that of Interpretation) Further process planning and process management Part 2a: Guide 4.2 4.3


Main choices In the course of this LCA phase, the supervisory process should be arranged so as to preserve the authoritativeness of the results. The potential input from stakeholders should also be used to improve the quality of the LCA. In this situation of ‘mandated science’, this implies that, depending on the specific process context, there should be room for interaction between the parties involved on topics that are relevant to the selection and definition of impact categories, characterisation methods, normalisation references, weighting principles and so on. Guidelines Guidelines for simplified and detailed LCA and optional extensions Determine the competencies and responsibilities of the LCA research scientists, any critical reviewers, the LCA clients and other interested parties, using Table 4.3.1. Address potential bottlenecks in the LCA process by making arrangements in line with Table 4.3.2 to ensure the orderly progress of the project. Table 4.3.1


Address potential bottlenecks in the LCA process by making arrangements in line with Table 4.3.2 to ensure the orderly progress of the project. Table 4.3.1. Overview of the competencies of the various actors during the LCA process for the different process contexts


Item 1a 1b 2a 2b 3a 3b Description first instructions with respect to fulfilment of LCA assignment first instructions with respect to fulfilment of assignment of critical reviewer written response to instruction on LCA assignment written response to instructions on assignment of critical reviewer1 possible revision of the first instructions on LCA assignment possible report on incompatible opinions on LCA assignment presentation of draft interim report (= draft text of Impact assessment report) written response to draft interim report on Impact assessment possible revision of draft report on Impact assessment possible report on incompatible opinions arising during the Impact assessment final opinion on final interim report on Impact assessment Process context I C – L – C L L C L L C II C or S C or S L + R R C or S L L + R C or S L + R L C or S III S S L + R R S L L + R S L + R L S Legend Process context I = few diverging interests, potentially strong impact Process context II = many


or S C or S L + R R C or S L L + R C or S L + R L C or S III S S L + R R S L L + R S L + R L S Legend Process context I = few diverging interests, potentially strong impact Process context II = many diverging interests, potentially weak impact Process context III = many diverging interests, potentially strong impact C = first LCA client(s) 1 The actual implementation of all guidelines in this Guide should be checked in a critical review


Part 2a: Guide


Part 2a: Guide S = stakeholders (including C) L = LCA research scientists R = critical reviewer Table 4.3.2 Overview of the arrangements that can be made between the various actors for the different process contexts


Item a b c d e Description widening/supplementation of the study (on request) validation by an independent expert (on request) binding advice on decision points by the critical O reviewer final decision-making by the biggest possible majority, arbitration or another previously determined procedure quantification of the influence of incompatible opinions in the final report Process context I o II r r r o r III r r r r r Legend Process context I = few diverging interests, potentially strong impact Process context II = many diverging interests, potentially weak impact Process context III = many diverging interests, potentially strong impact r = recommended o = option Example (case history) In the spring of 2000, the Waste Department of the Dutch Ministry of Environmental Affairs finished the OMA project, which aimed to develop an instrument for comparing the total environmental load of different waste policy options


This project was started in 1999, because of doubts about the general validity of the standard order of preference with respect to waste disposal (prevention, product reuse, materials recycling, incineration with energy recovery, dumping). The way this problem was addressed in practice was found to be problematic: “In those cases where it was decided to execute of an LCA, there have been differences in scope, environmental aspects taken into account and weighting methods. There is no systematic approach to the use of integral environmental analyses in waste policy.” A project group of staff members of the Waste Department addressed the problem in a few workshops together with selected staff members of other departments of the Ministry of Environmental Affairs. They discussed the results of a number of relevant LCA studies, focusing on key supplies and environmental aspects that were of overriding importance for the comparison of different waste disposal options


For the sake of communication and manageability, it was deemed desirable to restrict the number of environmental aspects to be taken into account. Important criteria for achieving a justifiable simplification turned out to be the size of the differences in the scores of the alternatives and the size of the contribution to the national environmental load. The staff members concluded that in the case of waste policy, the analysis could be restricted to three main environmental aspects: greenhouse effect, dumped waste and dispersion of hazardous substances. In the near future, this approach will be used to address a number of actual waste topics and to prepare the National Waste Plan.


4.3.2 Selection of impact categories Topic In the Impact assessment phase, the results of the Inventory analysis are translated into contributions to relevant impact categories, such as depletion of abiotic resources, climate change, acidification, etc. To this end, relevant impact categories must be identified. To facilitate the work of practitioners, a default list of impact categories has been elaborated, distinguishing between ’baseline’ impact categories, ’study-specific’ impact categories and ’other’ impact categories. In this step of the LCA, then, practitioners have to select those categories relevant to the goal of their particular study, supported by the preliminary selection made in this Guide. Main choices The list of best available practice impact categories drawn up by the SETAC Working Group on Impact Assessment has served as a basic list


Main choices The list of best available practice impact categories drawn up by the SETAC Working Group on Impact Assessment has served as a basic list. This choice is referred to below as the problem-oriented approach, because it is driven by environmental problems (the so-called mid-point of the cause-effect chain), rather than by damage (the end-point of this chain). Three sets of impact categories are distinguished (see Table 4.3.3), depending on the environmental relevance in relation to LCA and the availability of adequate characterisation methods 1 (see Section 4.3.3). Group A, “Baseline impact categories”, comprises those categories for which a baseline characterisation method is selected in Part 2b, and which are included in almost all LCA studies


Group A, “Baseline impact categories”, comprises those categories for which a baseline characterisation method is selected in Part 2b, and which are included in almost all LCA studies. Group B, “Study-specific impact categories”, comprises categories that may merit inclusion, depending on the goal and scope of the LCA study and whether appropriate data are available, and for which a baseline and/or alternative characterisation method is proposed in Part 2b. Group C, “Other impact categories”, comprises several categories for which no baseline characterisation method is proposed in this Guide, although alternative characterisation methods may be available. These impact categories require further elaboration before they can be used in LCA studies, with research still in progress. 1 The characterisation method for a given impact category comprises a category indicator, characterisation model and characterisation factors derived from the model. Part 2a: Guide


Table 4.3.3: Overview of baseline and other impact categories in relation to the availability of baseline characterisation methods. Impact category A. Baseline impact categories Depletion of abiotic resources Impacts of land use land competition Climate change Stratospheric ozone depletion Human toxicity Ecotoxicity freshwater aquatic ecotoxicity marine aquatic ecotoxicity terrestrial ecotoxicity Photo-oxidant formation Acidification Eutrophication B. Study-specific impact categories Impacts of land use loss of life support function loss of biodiversity Ecotoxicity freshwater sediment ecotoxicity marine sediment ecotoxicity Impacts of ionising radiation Odour malodourous air Noise Waste heat Casualties C


Other impact categories Depletion of biotic resources Desiccation Odour malodourous water Note: the list is restricted to the impact normalisation steps require reporting categories, as well as information on interventions not included in the model (Section Single baseline characterisation method available in the Guide? yes yes yes yes yes yes yes yes yes yes yes no no yes yes yes yes yes yes yes no no no Other characterisation method(s) available in the Guide? yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes no no no no yes no no categories. The results of the characterisation and of the calculated values for the selected impact 4.3.3.17) and economic flows not followed to the system boundary additional qualitative information. (Section 4.3.3.18), and Guidelines Guidelines for simplified LCA Use the problem-oriented approach with impact categories defined at mid-point level (see the glossary at the end of this Part)


(Section 4.3.3.18), and Guidelines Guidelines for simplified LCA Use the problem-oriented approach with impact categories defined at mid-point level (see the glossary at the end of this Part). If not, document and justify any other approach Part 2a: Guide


chosen. As an option for a sensitivity analysis, application of an endpoint-oriented approach such as Eco-indicator 99 or EPS is suggested. See references in Part 2b, Section 3.2. Include all or a selection of the baseline impact categories (group A) from Table 4.3.3. If a selection is made, justify this selection in relation to the goal of the study. Note that it is better to have "empty" impact categories than omissions. For instance, do not leave out the impact category of stratospheric ozone depletion for products that are "ozonefriendly", but show only zeroes in the classification and characterisation. Be flexible in including additional impact categories if the goal and scope of the study demands this (e.g., always include the additional effects of the land use subcategories of "loss of life support" and "loss of biodiversity" in a study on wood applications or studies involving forestry)


Practitioners can refer to this Guide for a description and justification of the choice of impact categories as required to meet ISO 14042 standards. If it is relevant to the study, the energy carriers extracted from the environment (coal, oil and gas) can be transformed into one total amount of extracted energy in MJ. See Part 2b, Table 4.3.1.5 for a list of upper and lower heating values for a number of energy carriers. This amount should then be given as a separate “impact” category. As an issue for the Interpretation phase, check whether the selection of impact categories is appropriate for the product(s) investigated, and if it is balanced in the case of a comparison. If no Impact assessment has been carried out, the reasons for this should be detailed. In the case of a comparison, select the same impact categories for each of the alternative product systems. Guidelines for detailed LCA All guidelines provided above for simplified studies apply here as well


Guidelines for detailed LCA All guidelines provided above for simplified studies apply here as well. In addition, the following guideline is given. From Table 4.3.3, include baseline impact categories (group A) and any study-specific impact categories (group B) relevant to the goal and scope of the study. Guidelines for optional extensions All guidelines provided above for detailed studies apply here as well. In addition, the following guideline is given. Consider whether it is justifiable, in relation to the goal and scope of the study, to add impact categories from group C or to add a new impact category. If so, document and justify comprehensively and transparently all requirements listed in Part 3, Section 4.1


If so, document and justify comprehensively and transparently all requirements listed in Part 3, Section 4.1. Example (hypothetical) “This LCA includes all baseline impact categories (group A), as well as freshwater and marine sediment toxicity, because the emission of toxics is generally felt to be one of the major problems for this product.” 4.3.3 Selection of characterisation methods: category indicators, characterisation models and factors Topic The interventions recorded in the inventory table are quantified in terms of a common category indicator. To this end, characterisation models are used, from which characterisation factors are derived for individual pollutants and so on. For a given impact category, a characterisation method comprises a category indicator, a characterisation model and characterisation factors derived from the model. The impact categories Part 2a: Guide


distinguished in this Guide (see 4.3.2) are treated individually in Sections 4.3.3.1 to 4.3.3.18, below, discussing the models, factors and indicators available for the category in question. Main choices Category indicators are chosen at mid-point level, since the end-point level is not comprehensive enough and is still being developed. The list of best available practice category indicators and characterisation models by the SETAC Working Group on Impact Assessment has served as a basic list


The list of best available practice category indicators and characterisation models by the SETAC Working Group on Impact Assessment has served as a basic list. In the selection of characterisation methods for every impact category, a distinction has been made into: a baseline characterisation method, i.e., the method recommended here as the current best available practice for the impact category in question; alternative characterisation methods, which may be adopted instead of the baseline method if duly justified and documented, or may be used in tandem with the baseline method, as a sensitivity analysis; additional characterisation methods, which may be applied like the alternative methods but require additional effort (e.g., collection of additional data, development of additional models); variant characterisation methods, which start from entirely different principles, and which are referred to in Part 3, but not tabulated in Part 2b


Guidelines Guidelines for simplified and detailed LCA Use the baseline characterisation method for each of the selected impact categories for which such a method exists.1 For certain impact categories, consider using one of the methods from the group of alternative methods. Justify this selection. Practitioners can refer to this Guide for a description and justification of the choice of these characterisation models and their related category indicators, as required to meet ISO 14042 standards. If an Impact assessment has been carried out, the methodology used should be clearly described in the report. Practitioners can refer to this Guide for a description and justification (as required to meet ISO 14042 standards) of the methods recommended as the baseline methods in this Guide. If other methods are used, these must be documented and justified in the report


If other methods are used, these must be documented and justified in the report. In the case of a comparison, check whether the Impact assessment has been conducted consistently between the various systems compared and whether the validity and reliability of the data sources used for Impact assessment is not too different for the various systems studied. Give a justification of the scientific and technical validity and environmental relevance of the category indicators and characterisation models used in the study. Practitioners can refer to this Guide for a description of the methods reviewed in this Guide. If other methods are used, reports must pay attention to the following topics. 1 The choice of baseline characterisation methods in the next twenty sections is based on the assumption that the problem-oriented approach has indeed been chosen, with the associated set of impact categories (see Section 4.3.2)


If Eco-indicator 99 and/or EPS has been chosen, the set of impact categories is considerably different from those discussed below. For a subset of impact categories, however, there is an overlap between the problem-oriented approach that is the default choice of this Guide and the alternative approaches (Ecoindicator 99, EPS). Many of the basic models used in Eco-indicator 99 and EPS, e.g. the fate and exposure model for the toxicity categories and the GWP model for climate change etc., are basically the same as those of the problem-oriented approach. Due to recent updates, however, this is as yet not the case, which may lead to ‘unnecessary’ inconsistencies. Part 2a: Guide


Can the choice of data sources for characterisation factors be justified in relation to the goal of the study and particularly to scope issues like temporal and geographical coverage? For instance, is the use of a particular model of acidification suitable and not designed for other regions than those where the bulk of the acidifying depositions will occur? What is the reliability of different data sources in qualitative terms? Are the sets of characterisation factors used complete? For instance, are any characterisation factors missing for interventions that are suspected to contribute to a given impact category? In the case of a comparison: are the above-mentioned issues not too different for the various systems studied? Include a description and justification of any new category indicators or characterisation models used for the Impact assessment, including all assumptions and limitations and all value choices made


Discuss their influence on the results, conclusions and recommendations Derive characterisation factors for the group parameter at stake, based on the arithmetic means of the individual species within that group for which characterisation factors are known. If, for example, only emission data on hydrocarbons are known, group POCPs can be derived as the arithmetic means of the POCPs of individual hydrocarbons. Include a statement as to whether or not international acceptance exists for the selected category indicators. In the case of a comparison, check whether the validity and reliability of the data sources used for Impact assessment is not potentially too different for the various systems studied. Guidelines for optional extensions All guidelines provided above for simplified and detailed studies apply here as well. In addition, the following optional guidelines are given. Use characterisation methods from the group of additional methods, where relevant


In addition, the following optional guidelines are given. Use characterisation methods from the group of additional methods, where relevant. Where relevant, use or develop other characterisation methods and describe these according to ISO 14042. Furthermore, an appropriate indication should be given of how the category indicator results have been, or are to be, calculated. Calculate, estimate or extrapolate characterisation factors for interventions which might be important for the case in hand but for which no characterisation factors are given in Part 2b of this Guide. The new factors could be calculated based on the baseline method (see the next sections), or estimated or extrapolated based on known characterisation factors for interventions which are comparable to the new interventions


Try whether, in addition to the superficial qualitative assessment of reliability mentioned under simplified and detailed LCA, more extensive qualitative and/or quantitative assessments of reliability can be made. Example (hypothetical) “In this LCA we have used the baseline characterisation methods developed by Guinée et al. (2001) for all selected impact categories.” 4.3.3.1 Depletion of abiotic resources Topic “Abiotic resources” are natural resources (including energy resources) such as iron ore, crude oil and wind energy, which are regarded as non-living. Abiotic resource depletion is one of the most frequently discussed impact categories and there is consequently a wide variety of methods available for characterising contributions to this category. To a large Part 2a: Guide


extent, these different methodologies reflect differences in problem definition. Depending on the definition, this impact category includes only natural resources, or natural resources, human health and the natural environment, among its areas of protection. Note that the debate on the characterisation of depletion-related impact categories is not settled


Main choices and guidelines Method status baseline alternative 1 alternative 2 alternative 3 additional variant Characterisation method/factor based on ultimate reserves and extraction rates based on economic reserves and extraction rates based on ultimate or economic reserves only based on exergy content – – Table in Part 2b 4.3.1.1 4.3.1.2 4.3.1.2 4.3.1.3 4.3.1.4 – – Example (for baseline) impact category LCI results characterisation model category indicator characterisation factor unit of indicator result abiotic depletion extraction of minerals and fossil fuels (in kg) concentration-based reserves and rate of de-accumulation approach depletion of the ultimate reserve in relation to annual use abiotic depletion potential (ADP) for each extraction of minerals and fossil fuels (in kg antimony equivalents/kg extraction) kg (antimony eq) Depletion of biotic resources Topic “Biotic resources” are material resources (including energy resources) regarded as living, e.g


rainforests, elephants. Depending on the precise definition adopted, this impact category has only natural resources, or natural resources, human health and the natural and the man-made environment as areas of protection. Main choices and guidelines Method status baseline alternative additional variant Characterisation method/factor – – based on reserves and deaccumulation rate – Table in Part 2b – – – – Example (for baseline) Depletion of biotic resources has been excluded, in line with the baseline recommendation. Part 2a: Guide 4.3.3.2


Impacts of land use Topic The category “Impacts of land use” covers a range of consequences of human land use. A distinction has been made between use of land with impacts on the resource aspect and use of land with impacts on biodiversity, life support functions, etc. Land competition Topic This subcategory of land use impacts is concerned with the loss of land as a resource, in the sense of being temporarily unavailable. The areas of protection are natural resources and the man-made environment


The areas of protection are natural resources and the man-made environment. Main choices and guidelines Method status baseline alternative additional variant Characterisation method/factor unweighted aggregation – – – Table in Part 2b –1 – – – Example (for baseline) impact category LCI results characterisation model category indicator characterisation factor unit of indicator result land competition land use (in unweighted aggregation land occupation 1 for all types of land use (dimensionless) (land use) Loss of biodiversity Topic In this impact category, the problems defined are the effects on biodiversity resulting from interventions such as harvesting biotic resources, or the destruction or alteration of land. Notice that the discussion on characterisation of land-use-related impact categories is far from settled


Notice that the discussion on characterisation of land-use-related impact categories is far from settled. Main choices and guidelines Method status baseline alternative alternative additional variant Characterisation method/factor – based on a statistical measure of species density based on a statistical measure of plant species density – – Table in Part 2b – – – – – 1 Characterisation factor is 1 throughout. Part 2a: Guide 4.3.3.3 4.3.3.3.1 4.3.3.3.2


Example (for baseline) Loss of biodiversity has been excluded, in line with the baseline recommendation. Loss of life support function Topic In this impact category, the problems defined are the effects on life support function resulting from interventions such as harvesting biotic resources, or the destruction or alteration of land. Notice that the discussion on characterisation of land-use-related impact categories is far from settled. Main choices and guidelines Example (for baseline) Method status baseline alternative additional variant Characterisation method/factor – based on Net Primary Production – – Table in Part 2b – – – – Loss of life support function has been excluded, in line with the baseline recommendation. Desiccation Topic Desiccation refers to a group of related environmental problems caused by water shortages due to groundwater extraction for industrial and potable water supply, enhanced drainage and water management (i.e. manipulation of the water table)


manipulation of the water table). This may lead to a lowered water table, reduced seepage, introduction of water from other areas and (consequently) changes in natural vegetation. The area of protection is the natural environment. Main choices and guidelines Method status baseline alternative additional variant Characterisation method/factor _ _ – – Table in Part 2b – – – – Example (for baseline) Desiccation has been excluded, in line with the baseline recommendation. Climate change Topic Climate change is defined here as the impact of human emissions on the radiative forcing (i.e. heat radiation absorption) of the atmosphere. This may in turn have adverse impacts on Part 2a: Guide 4.3.3.3.3 4.3.3.4 4.3.3.5


Part 2a: Guide ecosystem health, human health and material welfare. Most of these emissions enhance radiative forcing, causing the temperature at the earth’s surface to rise. This is popularly referred to as the ‘greenhouse effect’. The areas of protection are human health, the natural environment and the man-made environment


This is popularly referred to as the ‘greenhouse effect’. The areas of protection are human health, the natural environment and the man-made environment. impact category LCI results characterisation model category indicator characterisation factor unit of indicator result climate change emissions of greenhouse gases to the air (in kg) the model developed by the Intergovernmental Panel on Climate Change (IPCC) defining the global warming potential of different greenhouse gases infrared radiative forcing global warming potential for a 100-year time horizon (GWP100) for each greenhouse gas emission to the air (in kg carbon dioxide equivalent/kg emission) kg (carbon dioxide eq) 4.3.3.6 Stratospheric ozone depletion Topic Stratospheric ozone depletion refers to the thinning of the stratospheric ozone layer as a result of anthropogenic emissions


This causes a greater fraction of solar UV-B radiation to reach the earth’s surface, with potentially harmful impacts on human health, animal health, terrestrial and aquatic ecosystems, biochemical cycles and materials. Stratospheric ozone depletion thus impinges on all four areas of protection: human health, the natural environment, the man-made environment and natural resources. Method status baseline alternative 1 alternative 2 alternative 3 alternative 4 alternative 5 alternative 6 alternative 7 additional variant Characterisation method/factor – – Table in Part 2b 4.3.6.1 4.3.6.2 4.3.6.2 4.3.6.2 4.3.6.2 4.3.6.2 4.3.6.2 4.3.6.2 – – Main choices and guidelines Method status baseline alternative 1 alternative 2 alternative 3 alternative 4 additional variant Characterisation method/ upper limit of net GWP lower limit of net GWP – – factor Table in Part 2b 4.3.5.1 4.3.5.2 4.3.5.2 4.3.5.3 4.3.5.3 – – Example (for baseline) Main choices and guidelines


Part 2a: Guide impact category stratospheric ozone depletion LCI results emissions of ozone-depleting gases to the air characterisation model the model developed by the World Meteorological Organisation (WMO), defining the ozone depletion potential of different gases category indicator stratospheric ozone breakdown characterisation factor ozone depletion potential in the steady state (ODP steady state) for each emission to the air (in kg CFC-11 equivalent/kg emission) unit of indicator result kg (CFC-11 eq) 4.3.3.7 Human toxicity Topic This impact category covers the impacts on human health of toxic substances present in the environment. The health risks of exposure in the workplace are also sometimes included in LCA. These latter risks are often included in a wider impact category encompassing more than exposure to toxic substances (e.g. accidents at work). In this Guide, no further consideration is given to the impacts of exposure to toxic substances in the workplace


accidents at work). In this Guide, no further consideration is given to the impacts of exposure to toxic substances in the workplace. The area of protection for this impact category is human health. Notice that the discussion on characterisation of toxicity-related impact categories is far from settled


The area of protection for this impact category is human health. Notice that the discussion on characterisation of toxicity-related impact categories is far from settled. Method status baseline alternative 1 alternative 2 alternative 3 alternative 4 additional variant Characterisation method/factor – see Part 3 Table in 4.3.7.1 4.3.7.2 4.3.7.1 4.3.7.2 4.3.7.2 – – Part 2b impact category human toxicity LCI results emissions of toxic substances to air, water and soil (in kg) characterisation model USES 2.0 model developed at RIVM, describing fate, exposure and effects of toxic substances, adapted to LCA category indicator acceptable daily intake /predicted daily intake characterisation factor human-toxicity potential (HTP) for each emission of a toxic substance to air, water and/or soil (in kg 1,4-dichlorobenzene equivalent/kg emission) unit of indicator result kg (1,4-dichlorobenzene eq) Example (for baseline) Main choices and guideline Example (for baseline)


Part 2a: Guide 4.3.3.8 Ecotoxicity Topic This impact category covers the impacts of toxic substances on aquatic, terrestrial and sediment ecosystems. The area of protection is the natural environment (and natural resources). Notice that the discussion on characterisation of toxicity-related impact categories is far from settled. 4.3.3.8.1 Freshwater aquatic ecotoxicity Topic Freshwater aquatic ecotoxicity refers to the impacts of toxic substances on freshwater aquatic ecosystems


Method status Characterisation method/factor Table in Part 2b baseline alternative 1 alternative 2 alternative 3 alternative 4 additional variant – see Part 3 4.3.8.1 4.3.8.2 4.3.8.3 4.3.8.4 4.3.8.5 – – impact category LCI results characterisation model category indicator characterisation factor unit of indicator result freshwater aquatic ecotoxicity emissions of toxic substances to air, water and soil (in kg) USES 2.0 model developed at RIVM, describing fate, exposure and effects of toxic substances, adapted to LCA predicted environmental concentration/predicted no-effect concentration freshwater aquatic ecotoxicity potential (FAETP) for each emission of a toxic substance to air, water and/or soil (in kg 1 ,4dichlorobenzene equivalents /kg emission) kg (1,4-dichlorobenzene eq) 4.3.3.8.2 Marine aquatic ecotoxicity Topic This impact category covers impacts of toxic substances on marine aquatic ecosystems. Main choices and guidelines Example (for baseline)


Part 2a: Guide Method status baseline alternative 1 alternative 2 alternative 3 alternative 4 additional variant Characterisation method/factor – see Part 3 Table in Part 2b 4.3.8.1 4.3.8.2 4.3.8.3 4.3.8.4 4.3.8.5 – – Main choices and guidelines Example (for baseline) impact category LCI results characterisation model category indicator characterisation factor unit of indicator result marine aquatic ecotoxicity emissions of toxic substances to air, water and soil (in kg) USES 2.0 model developed at RIVM, describing fate, exposure and effects of toxic substances, adapted to LCA predicted environmental concentration/predicted no-effect concentration marine aquatic ecotoxicity potential (MAETP) for each emission of a toxic substance to air, water and/or soil (in kg 1,4dichlorobenzene equivalent/kg emission) kg (1,4-dichlorobenzene eq) 4.3.3.8.3 Terrestrial ecotoxicity Topic Terrestrial ecotoxicity refers to impacts of toxic substances on terrrestrial ecosystems


Main choices and guidelines Method status baseline alternative 1 alternative 2 alternative 3 alternative 4 additional variant Characterisation method/factor — see Part 3 Table in 4.3.8.1 4.3.8.2 4.3.8.3 4.3.8.4 4.3.8.5 _ – Part 2b


Part 2a: Guide Example (for baseline) impact category LCI results characterisation model category indicator characterisation factor unit of indicator result terrestrial ecotoxicity emissions of toxic substances to air, water and soil (in kg) USES 2.0 model developed at RIVM, describing fate, exposure and effects of toxic substances, adapted to LCA predicted environmental concentration/predicted no-effect concentration terrestrial ecotoxicity potential (TETP) for each emission of a toxic substance to air, water and/or soil (in kg 1,4dichlorobenzene equivalents/kg emission) kg (1 ,4-dichlorobenzene eq) 4.3.3.8.4 Freshwater sediment ecotoxicity Topic Freshwater sediment ecotoxicity refers to impacts of toxic substances on the sediment of freshwater ecosystems


Main choices and guidelines Method status baseline alternative 1 alternative 2 alternative 3 alternative 4 additional variant Characterisation method/factor – see Part 3 Table in Part 2b 4.3.8.1 4.3.8.2 4.3.8.3 4.3.8.4 4.3.8.5 – – Example (for baseline) impact category LCI results characterisation model category indicator characterisation factor unit of indicator result freshwater sediment ecotoxicity emissions of toxic substances to air, water and soil (in kg) USES 2.0 model developed at RIVM, describing fate, exposure and effects of toxic substances, adapted to LCA predicted environmental concentration/predicted no-effect concentration freshwater sediment ecotoxicity potential (FSETP) for each emission of a toxic substance to air, water and/or soil (in kg 1 ,4dichlorobenzene equivalents/kg emission) kg (1,4-dichlorobenzene eq) 4.3.3.8.5 Marine sediment ecotoxicity Topic Marine sediment ecotoxicity refers to impacts of toxic substances on the sediment of sea water ecosystems.


Part 2a: Guide Main choices and guidelines Method status baseline alternative 1 alternative 2 alternative 3 alternative 4 additional variant Characterisation method/factor — see Part 3 Table in Part 2b 4.3.8.1 4.3.8.2 4.3.8.3 4.3.8.4 4.3.8.5 — - Example (for baseline) impact category LCI results characterisation model category indicator characterisation factor unit of indicator result marine sediment ecotoxicity emissions of toxic substances to air, water and soil (in kg) USES 2.0 model developed at RIVM, describing fate, exposure and effects of toxic substances, adapted to LCA predicted environmental concentration/predicted no-effect concentration marine sediment ecotoxicity potential (MSETP) for each emission of a toxic substance to air, water and/or soil (in kg 1 ,4dichlorobenzene equivalents/kg emission) kg (1,4-dichlorobenzene eq) 4.3.3.9 Photo-oxidant formation Topic Photo-oxidant formation is the formation of reactive chemical compounds such as ozone by the action of sunlight


emission) kg (1,4-dichlorobenzene eq) 4.3.3.9 Photo-oxidant formation Topic Photo-oxidant formation is the formation of reactive chemical compounds such as ozone by the action of sunlight on certain primary air pollutants


These reactive compounds may be injurious to human health and ecosystems and may also damage crops. The relevant areas of protection are human health, the man-made environment, the natural environment and natural resources. Photo-oxidants may be formed in the troposphere under the influence of ultraviolet light, through photochemical oxidation of Volatile Organic Compounds (VOCs) and carbon monoxide (CO) in the presence of nitrogen oxides Ozone is considered the most important of these oxidising compounds, along with peroxyacetylnitrate (PAN). Photooxidant formation, also known as summer smog, Los Angeles smog or secondary air pollution, contrasts with winter smog, or London smog, which is characterised by high levels of inorganic compounds, mainly particles, carbon monoxide and sulphur compounds. This latter type of smog causes bronchial irritation, coughing, etc. Winter smog, as far as considered in this Guide, is part of human toxicity.


Part 2a: Guide Main choices and guidelines Method status baseline alternative 1 alternative 2 alternative 3 alternative 4 additional variant Characterisation method/factor high NOx POCP MIR MOIR EBIR low NOx POCP – – Table in Part 2b 4.3.9.1 4.3.9.2 4.3.9.2 4.3.9.2 4.3.9.3 – – Example (for baseline) impact category LCI results characterisation model category indicator characterisation factor unit of indicator result photo-oxidant formation emissions of substances (VOC, CO) to air (in kg) UNECE Trajectory model tropospheric ozone formation photochemical ozone creation potential (POCP) for each emission of VOC or CO to the air (in kg ethylene equivalents/kg emission) kg (ethylene eq) 4.3.3.10 Acidification Topic Acidifying pollutants have a wide variety of impacts on soil, groundwater, surface waters, biological organisms, ecosystems and materials (buildings). Examples include fish mortality in Scandinavian lakes, forest decline and the crumbling of building materials


Examples include fish mortality in Scandinavian lakes, forest decline and the crumbling of building materials. The major acidifying pollutants are and Areas of protection are the natural environment, the man-made environment, human health and natural resources. Main choices and guidelines Method status Characterisation method/factor baseline average European AP alternative generic AP additional region (site) dependent AP variant see Part 3 Table in Part 2b 4.3.10.1 4.3.10.2 4.3.10.3 – Example (for baseline) impact category LCI results characterisation model category indicator characterisation factor unit of indicator result acidification emissions of acidifying substances to the air (in kg) RAINS10 model, developed at IIASA, describing the deposition of acidifying substances, adapted to LCA deposition/acidification critical load acidification potential (AP) for each acidifying emission (in kg equivalents /kg emission) kg fate and to the air


Part 2a: Guide 4.3.3.11 Eutrophication Topic Eutrophication covers all potential impacts of excessively high environmental levels of macronutrients, the most important of which are nitrogen (N) and phosphorus (P). Nutrient enrichment may cause an undesirable shift in species composition and elevated biomass production in both aquatic and terrestrial ecosystems. In addition, high nutrient concentrations may also render surface waters unacceptable as a source of drinking water. In aquatic ecosystems increased biomass production may lead to a depressed oxygen levels, because of the additional consumption of oxygen in biomass decomposition (measured as BOD, biological oxygen demand). As emissions of degradable organic matter have a similar impact, such emissions are also treated under the impact category “eutrophication”. The areas of protection are the natural environment, natural resources and the man-made environment


The areas of protection are the natural environment, natural resources and the man-made environment. Main choices and guidelines Method status Characterisation method/factor baseline generic EP alternative average European EP additional region (site) dependent EP variant – Table in Part 2b 4.3.11.1 4.3.11.2 4.3.11.2 – Example (for baseline) impact category LCI results characterisation model category indicator characterisation factor unit of indicator result eutrophication emissions of nutrients to air, water and soil (in kg) the stoichiometric procedure, which identifies the equivalence between N and P for both terrestrial and aquatic systems deposition/N/P equivalents in biomass eutrophication potential (EP) for each eutrophying emission to air, water and soil (in kg equivalents/kg emission) kg 4.3.3.12 Waste heat Topic Emissions of waste heat may increase temperatures on a local scale: in a city or lake, for example


They cannot contribute to global warming on a scale such as that associated with emissions of greenhouse gases. The effects on ecosystems of waste heat emissions to the air are negligible. Depending on local conditions, the discharge of waste heat into surface waters may result in a substantial temperature rise, with a consequent impact on local aquatic ecosystems. In this Guide waste heat is treated as a separate impact category, although it covers only aquatic emissions of waste heat such as cooling water emissions from power stations. The areas of protection are the natural environment and natural resources.


Part 2a: Guide Main choices and guidelines Method status Characterisation method/factor baseline unweighted aggregation of energy alternative additional variant Table in Part 2b – – – Example impact category LCI results characterisation model category indicator characterisation factor unit of indicator result waste heat emissions of heat (in MJ) to water unweighted aggregation heat released 1 (dimensionless) MJ (heat) 4.3.3.13 Odour Topic Odour becomes a problem when a given concentration of odorous substances is experienced as unpleasant. Whether an odour is experienced as stench will depend on the particular individual exposed. Above a certain emission level, however, every individual will experience it as such. Here, the term odour will be used for effects. The area of protection is human health. 4.3.3.13.1 Malodorous air Topic This subcategory involves airborne odour


Here, the term odour will be used for effects. The area of protection is human health. 4.3.3.13.1 Malodorous air Topic This subcategory involves airborne odour. Main choices and guidelines Method status Characterisation method/factor baseline inverse OTV alternative – additional based on fate model and odour threshold values variant Table in Part 2b 4.3.13.1 – – – Example (for baseline) impact category LCI results characterisation model category indicator characterisation factor unit of indicator result malodorous air emissions of odorous substances (in kg) to the air reciprocal of odour threshold value in the air volume of air filled to the odour threshold value reciprocal of odour threshold value (1/OTV, in (air) 1 Characterisation factor is 1 throughout. – – – – –


Part 2a: Guide 4.3.3.13.2 Malodorous water Topic This subcategory deals with water-borne odour. Main choices and guidelines Method status Characterisation method/factor Table in Part 2b baseline – alternative additional variant Example (for baseline) Malodorous water has been excluded, in line with the baseline recommendation. 4.3.3.14 Noise Topic Noise, or noise nuisance, refers to the environmental impacts of sound. In principle, these impacts could cover at least human health and ecosystem health, but the environmental mechanisms are complex, non-linear and highly dependent upon local circumstances. Moreover, noise is similar to odour in that a given level of exposure is experienced differently by different individuals. Something considered a nuisance by one person might be appreciated by another, as exemplified by the case of loud music. Hence, whether or not sound waves will lead to ’nuisance’ depends partly on the actual situation and partly on the person interviewed


Hence, whether or not sound waves will lead to ’nuisance’ depends partly on the actual situation and partly on the person interviewed. Main choices and guidelines Method status baseline alternative additional variant Characterisation method/factor unweighted aggregation of sound – based on DALY – Table in Part 2b –– – – Example (for baseline) impact category LCI results characterisation model category indicator characterisation factor unit of indicator result noise emissions of sound (in unweighted aggregation sound (sound) 1 Characterisation factor is 1 throughout. – – – – – – –


Part 2a: Guide 4.3.3.15 Impacts of ionising radiation Topic The impact category 'impacts of ionising radiation' covers the impacts arising from releases of radioactive substances as well as direct exposure to radiation, in building materials for example. Exposure to ionising radiation is harmful to both human beings and animals. The areas of protection are therefore human health, the natural environment and natural resources. Ionising radiation is expressed in terms of the number of atoms disintegrating (or decaying) per unit time. The SI unit of radioactivity is the becquerel (Bq), one Bq corresponding to one disintegration per second. The radioactivity of a substance is expressed in or Radioactivity always declines in the course of time and the time taken for the radioactivity of a given substance to decline by half is known as the half-life of the substance


Main choices and guidelines Method status Characterisation method/factor baseline ionising radiation damage factors alternative screening factors –level I additional screening factors –level II variant Table in Part 2b 4.3.15.1 4.3.15.2 — - Example (for baseline) impact category LCI results characterisation model category indicator characterisation factor unit of indicator result impacts of ionising radiation emissions of ionising radiation to air, water and soil (in kBq1) fate and exposure models combined with epidemiological studies and the concept of disability-adjusted life years (DALY) disability-adjusted life years (DALY) ionising radiation damage factors for each ionising radiation emission to air, water and/or soil (in yr/kBq emission) yr 4.3.3.16 Casualties Topic This impact category refers to casualties resulting from accidents. The area of protection is human health


The area of protection is human health. Main choices and guidelines Method status Characterisation method/factor baseline unweighted aggregation of victims alternative additional variant Table in Part 2b 1 Emissions of ionising substances in kg can be converted to Bq or kBq; see Part 2b, Section 3.6. 2 Characterisation factor is 1 throughout. - -- --2 - --


Part 2a: Guide Example impact category LCI results characterisation model category indicator characterisation factor unit of indicator result casualties number of victims (dimensionless) unweighted aggregation number of victims 1 (dimensionless) dimensionless 4.3.3.17 Interventions for which characterisation factors are lacking Topic Many practical cases will involve emissions of toxic chemicals for which no toxicity potentials are listed in the tables with characterisation factors. The same applies to acidifying substances, ionising substances, depletable resources and so on. A general guideline given for extended LCAs is to calculate, estimate or extrapolate missing characterisation factors. This will often be unfeasible, however, for lack of time or knowledge, for instance


This will often be unfeasible, however, for lack of time or knowledge, for instance. In such cases these overlooked items should be discussed in a separate part of the Impact assessment Main choices A distinction should be made between: interventions that are known to contribute to an impact category, for which no characterisation factor is available but for which a factor can be calculated, estimated or extrapolated; interventions that are known to contribute to an impact category, but for which no characterisation factor can be found, calculated, estimated or extrapolated; interventions assumed to be environmentally relevant but not contributing to any of the selected impact categories; interventions assumed not to be environmentally relevant


Guidelines Guidelines for simplified and detailed LCA and optional extensions Include interventions for which a characterisation factor can be calculated, estimated or extrapolated in the environmental profile under the relevant impact category, accompanied by a clear explanation of the divergent status of the characterisation factor and the method used to obtain it. Include interventions for which no characterisation factor can be calculated, estimated or extrapolated but which are known to contribute to one or more impact categories in a separate part of the environmental profile labelled "Interventions for which characterisation factors are lacking", accompanied by all relevant additional information such as: substance name; emission compartment; amount emitted; impact category to which a contribution is suspected; if possible, an indication of the significance of the suspected impact; see Part 2b, Section 4.3.17


Include interventions known to be of environmental relevance but contributing to an impact category that is not selected in the environmental profile in the same way.


Part 2a: Guide Interventions expected to be environmentally irrelevant can be excluded from the environmental profile, but this should be transparently justified in the LCA report. Example (hypothetical) “The inventory table contains the entry "dioxins (unspecified)". Although dioxins are known to be extremely toxic, this entry does not show up in the list of characterisation factors for the models selected to address human toxicity and ecotoxicity. This could lead to a gross underestimate of the indicator results. In a sensitivity analysis, a worst-case influence can be investigated by replacing it with 2,3,7,8-TCDD (tetrachloride-dibenzo-dioxin), for which characterisation factors are available. Furthermore, emissions of 1-butene contribute to photo-oxidant formation but not to the impact categories that relate to toxicity. This can be justified because this substance is generally agreed to be non-toxic, although it is very explosive


This can be justified because this substance is generally agreed to be non-toxic, although it is very explosive. The latter aspect, however, is outside the scope of LCA, although it should be addressed in a separate analysis of safety.” 4.3.3.18 Economic flows not followed to system boundary Topic LCAs may comprise certain flows that are not specified in terms of environmental interventions, either inputs, like energy or materials, or outputs, like solid waste. Every effort should be made to avoid such flows, in the first place by applying the data estimation methods outlined in Section 3.3.8. All economic flows that cannot be followed to the system boundary should then be listed in a separate category: “Economic flows not followed to system boundary”. Flows listed in this category should always be described qualitatively (e.g. ‘hazardous waste’ and ‘non-hazardous waste’) and, wherever possible, quantitatively (e.g. truck)


Flows listed in this category should always be described qualitatively (e.g. ‘hazardous waste’ and ‘non-hazardous waste’) and, wherever possible, quantitatively (e.g. truck). Main choices Economic flows should as much as possible be estimated, rather than cut off. Only if such estimation is not feasible, can a cut-off be applied, and these flows are then to be listed in the present category. Guidelines Guidelines for simplified LCA List economic flows that are not followed to the system boundary qualitatively and quantitatively and as part of the environmental profile as a separate category, labeled “Economic flows not followed to the system boundary”. Discuss these flows in the Interpretation. Guidelines for detailed LCA Estimate the possible contribution to the impact categories of flows not followed to the system boundary by applying the procedure described in Section 3.3.8


Guidelines for detailed LCA Estimate the possible contribution to the impact categories of flows not followed to the system boundary by applying the procedure described in Section 3.3.8. If this is not possible, list the flows concerned qualitatively and quantitatively and as part of the environmental profile, and discuss these flows in the Interpretation. Guidelines for optional extensions All guidelines provided above for detailed LCA apply here. In addition, the following guideline is given:


Part 2a: Guide Decide and justify whether or not it is important to collect specific process data for a specific flow not followed to the boundary, based on an estimation of the possible contribution to the impact categories. If so, collect specific process data for that flow. Example (hypothetical) See the example under Characterisation. 4.3.4 Classification Topic In this step the environmental interventions qualified and quantified in the Inventory analysis are assigned on a purely qualitative basis to the various pre-selected impact categories (see Section 4.3.2). For a baseline list of interventions, for which characterisation factors have previously been derived, the classification step involves no actual work as these interventions have already been assigned to the various impact categories in this Guide (see Section 4.4 of Part 2b of this Guide). In the case of other interventions the practitioner will have to adopt an appropriate procedure of his own


In the case of other interventions the practitioner will have to adopt an appropriate procedure of his own. Main choices As long as a characterisation step is performed and reported with due attention to the category of "Interventions for which characterisation factors", no explicit implementation or reporting of the classification step is required. It may sometimes be important to consider interventions contributing to more than one impact category in more detail


We distinguish the following types: emissions with parallel impacts, i.e., emissions of substances that may theoretically contribute to more than one impact category but in practice contribute only to one, e.g., an emission of which may have either toxic or acidifying impacts; emissions with serial impacts, i.e., emissions of substances that may in practice have successive impacts, e.g., emissions of heavy metals which may first have ecotoxicological impacts and subsequently, via food chains, impacts on human health; emissions with indirect impacts, i.e., emissions of substances having a primary impact that in turn leads to one or more secondary impacts, e.g., aluminium toxicity induced by acidification, or methane contributing to photo-oxidant formation, with the ozone produced contributing to climate change, which in turn may contribute to stratospheric ozone depletion; emissions with combined impacts, i.e., emissions of substances having a mutual influence on each other’s impacts,


to climate change, which in turn may contribute to stratospheric ozone depletion; emissions with combined impacts, i.e., emissions of substances having a mutual influence on each other’s impacts, e.g., synergistic or antagonistic impacts of mixtures of toxic substances, or and VOC, both of which are required for photo-oxidant formation


Guidelines Guidelines for simplified and detailed LCA and optional extensions If the lists of characterisation factors recommended in Section 4.3.3 are observed, no action is required from the practitioners with respect to interventions for which characterisation factors have been defined. If the study’s inventory table includes interventions that lack appropriate characterisation factors (in this Guide), the guidelines specified above in section 4.3.3.17 on


Part 2a: Guide "Interventions for which characterisation factors are lacking" lead to additional entries in a classification table. Interventions with serial and combined impacts are fully assigned to all relevant impact categories in the proposed baseline method. The partial assignment of interventions with parallel impacts is addressed, as much as possible, by means of fate models in the characterisation models, and does not need to be effected as part of the classification step. Where proper fate treatment is not yet possible, a full assignment to all relevant impact categories is to be made. Example (hypothetical) No example. 4.3.5 Characterisation Topic In the characterisation step of Impact assessment the environmental interventions assigned qualitatively to a particular impact category in classification are quantified in terms of a common unit for that category, allowing aggregation into a single score: the indicator result


The resulting figure for one particular impact category is referred to as a category indicator result, and the complete set of category indicator results as the environmental profile. Main choices If the choices of impact categories and category indicators are explicitly addressed, characterisation is a technical step, and emphasis can be put on proper reporting of the characterisation results. Guidelines Guidelines for simplified and detailed LCA and optional extensions For each alternative studied, calculate the environmental profile by multiplying the interventions of inventory results by their concomitant characterisation factors and aggregating the results of these multiplications for each impact category. See Part 2b, Section 4.3 for specific equations and factors


See Part 2b, Section 4.3 for specific equations and factors. If a separate “impact” category of energy (in MJ) has been defined (see Section 4.3.3), transform the energy carriers extracted from the environment (coal, oil and gas) into one total amount of extracted energy in MJ by multiplying the amount used by the heating value (see Part 2b, Table 4.3.5.3). Report the category indicator results, the interventions for which characterisation factors and/or methods are lacking, the flows that have not been followed up to the system boundary, and additional remarks in separate tables or in separate sections of one table. It is often convenient to report characterisation results for all alternatives studied in one table. An example form to report characterisation results is provided in Part 2b, Section 4.3.5.


Part 2a: Guide Example (hypothetical) The results of the Inventory analysis are transformed after characterisation into the environmental profile shown below. Impact category Value indicator results depletion of abiotic resources photo-oxidant formation climate change freshwater aquatic ecotoxicity terrestrial ecotoxicity human toxicity acidification eutrophication 3.5 kg antimony eq ethylene eq 2.2 kg CO2 eq 0.013 kg 14DCB eq 14DCB eq 0.0088 kg 14DCB eq 0.033 kg SO2 eq PO4 eq interventions for which characterisation factors are lacking emission to air: dioxins (unspecified) economic outflows not followed to system boundary used plastic bags residue to dump recovered energy 0.08 kg 0.0008 MJ 4.3.6 Normalisation Topic ISO 14042 defines normalisation as “calculation of the magnitude of indicator results relative to reference information”. The reference information may relate to a given community (e.g., The Netherlands, Europe or the world), person (e.g


The reference information may relate to a given community (e.g., The Netherlands, Europe or the world), person (e.g. a Danish citizen) or other system, over a given period of time. Other reference information may also be adopted, of course, such as a future target situation. The main aim of normalising the category indicator results is to better understand the relative importance and magnitude of these results for each product system under study. Normalisation can also be used to check for inconsistencies, to provide and communicate information on the relative significance of the category indicator results and to prepare for additional procedures such as weighting or Interpretation. Main choices Normalisation is regarded as a strongly recommended step for any LCA


Main choices Normalisation is regarded as a strongly recommended step for any LCA. Guidelines Guidelines for simplified and detailed LCA For each alternative studied, calculate a normalised environmental profile by dividing the impact scores for each impact category by their concomitant normalisation factors. Use normalisation data based on one geographically and temporally well-defined reference system, preferably the world for one year, for all impact categories. The method based on total world interventions (method 1) or that based on the interventions of an average world citizen (method 2) are both applicable. Which one is chosen depends on the goal of the study. Part 2b, Section 4.6 provides several sets of normalisation factors per impact category for the baseline impact category indicators (see Section 4.3.3).


Part 2a: Guide For other category indicators, use the unaggregated data (interventions per reference area and period) to calculate normalisation factors. This can be done by applying the characterisation factors of an indicator on the interventions and adding them up to category indicator results (see Part 2b, Section 4.6 for references to the unaggregated data). If other normalisation methods are used (e.g., combining different scales) these should be described and justified in relation to the goal and scope of the study. If different scales are combined: use only per capita normalisation data; base the normalisation data for regional impact categories on the regions where the interventions of the relevant LCA study have taken place; if grouping or weighting is performed, group or weight the regionally normalised data using regional grouping methods or regional weighting factors; pay attention in the Interpretation to the seriousness of the impact categories in the regions concerned


Normalisation factors do not need to be reported for the baseline normalisation method and impact categories if appropriate reference is made to the data set in Part 2b, including the publication date of the document. Normalisation factors not included in Part 2b should always be reported. Report normalised indicator results for every impact category. It is often convenient to report normalised indicator results for all alternatives studied in one table. An example form is provided in Part 2b, Section 4.6. When reporting normalised indicator results, specify the unit. If the result is dimensionless, this must also be stated explicitly. The preferred unit for normalised indicator results is a year. In the case of a comparison, check whether the validity and reliability of the data sources used to derive reference values for normalisation are not (potentially) too different for the various systems studied


Guidelines for optional extensions All guidelines provided above for detailed studies apply here. In addition, the following guidelines are given: Fill (some of the) gaps in existing sets by collecting data on the magnitude of an intervention which is relevant to the study but which is not included in the normalisation data given in this Guide. Assess the reliability of different data sources in qualitative terms: Check whether the sets of normalisation factors which are used are mutually consistent. More specifically, check whether choices with respect to the economyenvironment system boundary, cut-off, allocation, characterisation methods, etc. are consistent between normalisation factors and case. Check whether sets of reference values used for normalisation are complete. Example (hypothetical) “In this example, the situation in the Netherlands is taken as a reference for all impact categories


Example (hypothetical) “In this example, the situation in the Netherlands is taken as a reference for all impact categories. This is in line with the goal of the study, which is to identify hot spots in the product system of PE bags in the Netherlands. The reference information used refers to the year 1993, because this was the most recent complete list that was available. The results of the Inventory analysis after normalisation are shown in the normalised environmental profile below.


Part 2a: Guide Impact category Value normalised indicator results depletion of abiotic resources photo-oxidant formation climate change freshwater aquatic ecotoxicity terrestrial ecotoxicity human toxicity acidification eutrophication 2.2E–11 yr 2.6E–15 yr 5.7E–14 yr 6.7E–15 yr 6.8E–18 yr 1.8E–16 yr 1.1E–13 yr 3.7E–15 yr interventions for which characterisation factors are lacking emission to air: dioxins (unspecified) 8.1E–14 kg economic outflows not followed to system boundary used plastic bags residue to dump recovered energy 0.08 kg 0.0008 MJ 4.3.7 Grouping Topic Grouping is a step of Impact assessment in which impact categories are aggregated into one or more sets. It is an optional element for which two possible procedures are available: sorting and ranking, defined by ISO as follows: sorting of the category indicators on a nominal basis e.g


It is an optional element for which two possible procedures are available: sorting and ranking, defined by ISO as follows: sorting of the category indicators on a nominal basis e.g. by characteristics such as emissions and resources or global regional and local spatial scales; ranking of the category indicators on an ordinal scale, e.g. a given order or hierarchy, such as high, medium and low priority (ranking is based on valuechoices). Main choices Grouping is optional; it is allowed within ISO 14042 for comparative assertions Guidelines Guidelines for simplified and detailed LCA Grouping is an optional step in LCA, for which no clear method is available. It is therefore not specifically applicable, except for optional extensions. Guidelines for optional extensions Grouping is an optional step in LCA, for which no clear method is available. If this is to be applied, a method, including criteria for grouping, must be developed


Guidelines for optional extensions Grouping is an optional step in LCA, for which no clear method is available. If this is to be applied, a method, including criteria for grouping, must be developed. Present the results of the grouping of impact categories as a matrix on the basis of the criteria used. The following criteria can be used as the starting point for ranking, but the criteria to be used depend on the goal and scope of the study: ecological threat potential; reversibility of the effect; scale of the effect; environmental preference of the population;


Part 2a: Guide relationship between current and/or previous pollution and quality goals. When grouping is applied, describe and justify extensively the method and criteria used to sort or rank the impact categories. When grouping or ranking is applied, include the following statements in the report


When grouping or ranking is applied, include the following statements in the report. A statement to the effect that conclusions and recommendations derived from grouping are based on value choices and that “The value choices and judgements used in the grouping procedures are the sole responsibility of the commissioner of the study (e.g., government, community, organisation, etc)" A statement to the effect that “The ISO 14042 standard does not specify any specific methodology or support the underlying value choices used to group or rank the impact categories" Example (hypothetical) “No grouping has been performed, as the literature provides no clearly described method.” 4.3.8 Weighting Topic Weighting is an optional step of Impact assessment, in which the (normalised) indicator results for each impact category assessed are assigned numerical factors according to their relative importance, multiplied by these factors and possibly aggregated. Weighting is based on value choices (e.g


Weighting is based on value choices (e.g. monetary values, standards, expert panel). A convenient name for the result of the weighting step is ‘weighting result’, of which there is generally one for each alternative product system analysed. The term ‘weighting profile’ is used in this Guide for the overall result of the weighting step: a table showing all the weighting results, supplemented by any other relevant information. Main choices Weighting is an optional step for all non-comparative assertions; it is not allowed within ISO 14042 for comparative assertions disclosed to the public. There is no best available method, and there is no recommended set of weighting factors. Guidelines Guidelines for simplified and detailed LCA Weighting is an optional step in LCA, for which no baseline method is proposed in this Guide


Guidelines Guidelines for simplified and detailed LCA Weighting is an optional step in LCA, for which no baseline method is proposed in this Guide. It is therefore not specifically applicable, except for optional extensions.1 Guidelines for optional extensions According to ISO 14042, weighting is not allowed for comparative assertions disclosed to the public. One must therefore decide whether to ignore the ISO principles, keep results internal, or refrain from weighting. If a weighting is performed, first formulate the conclusions that can be drawn without weighting. 1 Certain other approaches to Impact assessment, such as Eco-indicator 99 and EPS, include operational weighting. If a weighted single result is desired in a simple or detailed LCA, one of these approaches should be selected in Section 4.3.2. We would discourage straightforward application of the weighting factors of Ecoindicator 99 and EPS to this Guide’s problem-oriented approach.


Part 2a: Guide Weighting is an optional step in LCA, for which no clear method is available. If this is to be applied, a method, including weighting factors, must be developed. The results of the environmental profile must in most cases be equalised as to their units before weighting. A possible method for this is normalisation (see Section 4.3.6). If normalisation is performed before weighting and this normalisation is done on different scale levels (combining regional and world scales in one LCA), weighting must also be based on these different scale levels and the regions where the interventions included in the study took place. The preferred method is the use of a complete, nationally or internationally authorised set of weighting factors covering all relevant impact categories. However, as long as such a set does not exist, one might consider developing a case-specific set of weighting factors that is most appropriate to the goal of the study


However, as long as such a set does not exist, one might consider developing a case-specific set of weighting factors that is most appropriate to the goal of the study. For this set, consider the following suggestions. Base the weighting factors preferably on a panel method, including all relevant parties, or should be based on publicly revealed preference data. use more than one method to develop weighting factors. Instead of single value weighting factors per impact category, use ranges based on the different views in the consultation panel or the different results of the various methods used. There are technical details that may be quite important, including the composition of the panel, the questions posed to the members of the panel, the degree of interaction between the members of the panel and the possible subdivision of impact categories into subcategories. Avoid the use of an implicit or temporary weighting factor of 1


Avoid the use of an implicit or temporary weighting factor of 1. Report any further procedures that transform the category indicator results and provide a justification of the selected references, weighting factors, etc. If weighting has been undertaken, explain and justify the methodology clearly, both for quantitative and qualitative approaches. Document all advantages and disadvantages and relate them to the goal and scope. Justify the choice of weighting factors in relation to the goal of the study and particularly in relation to scope issues such as temporal and geographical coverage. If weighting has been undertaken, list all interventions and impact categories not included in the weighting directly under the weighting results (including those interventions not characterised)


If weighting has been undertaken, list all interventions and impact categories not included in the weighting directly under the weighting results (including those interventions not characterised). In the case of a comparison, check whether the validity and reliability of the data sources used to derive weighting factors are not (potentially) too different for the various systems studied? Example (hypothetical) “A social panel approach has been chosen for the weighting. Details on how the panel has been instructed are provided in an appendix. The weighting factors used and the results of weighting are listed below.


Part 2a: Guide Impact category Weight Value weighted indicator results depletion of abiotic resources photo-oxidant formation climate change freshwater aquatic ecotoxicity terrestrial ecotoxicity human toxicity acidification eutrophication 0.01 0.8 2.4 0.2 0.4 1.1 1.3 1.0 2.2E–13 yr 2.1E–15 yr 1.4E–13 yr 1.3E–15 yr 3.9E–18 yr 1.9E–16 yr 1.4E–13 yr 3.7E–15 yr weighting result total – 5.1E–13 yr interventions for which characterisation factors are lacking emission to air: dioxins (unspecified) 8.1E–14 kg economic outflows not followed to system boundary used plastic bags residue to dump recovered energy – – – 0.08 kg 0.0008 MJ Observe that the weighting result is dominated by three impact categories: depletion of abiotic resources, acidification and climate change.” 4.4 Results of Impact assessment The main results of this phase, which is the input of the next phase, Interpretation, include the environmental profile, the normalised environmental profile and the weighting profile.


5.1 Topic Life Cycle Interpretation is the phase in which the results of the analysis and all choices and assumptions made during the course of the analysis are evaluated in terms of soundness and robustness, and overall conclusions are drawn. The main elements of the Interpretation phase are an evaluation of results (in terms of consistency and completeness), an analysis of results (for instance, in terms of robustness), and the formulation of the conclusions and recommendations of the study. 5.2 Starting points ISO 14043 has played a central role in the elaboration of this phase. Within this framework, three main categories of activities have been identified: evaluation of results; analysis of results; conclusions and recommendations. In addition, as in the previous phases, special attention has been given to the procedures for managing the LCA. Additional starting points for the Interpretation phase in this Guide include the following