ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 8 Life Cycle Impact Assessment - calculating LCIA results Acidification). They reflect only the contribution of the analysed product to the total impact potential but not the severity/relevance of the respective total impact. Therefore, also the normalised LCIA results should not directly be summed: summing them up directly is equivalent to choose an equal weight for all impact categories. Hence, a weighting is always at least implicitly involved when summing up normalised LCIA results. If summing or comparison across the normalised LCIA results is intended, this shall include a explicit weighting step with equal weights. The same holds true for normalised LCIA results on endpoint level, as the damage to e.g. the Natural environment may be judged as a more relevant issue than e.g. the depletion of Natural resources


The same holds true for normalised LCIA results on endpoint level, as the damage to e.g. the Natural environment may be judged as a more relevant issue than e.g. the depletion of Natural resources. To directly compare or sum up results across categories or areas of protection, an additional weighting step is to be done, which is equally an optional step under ISO 14044:2006. Provisions: 8.3 Normalisation Note that this provision applies to all types of deliverables of the study, while for unit process, partly terminated system, LCI results and LCIA results data sets as deliverables only if the use of normalised and weighted LCIA results has been selected to quantify the achieved completeness and precision (these need to be evaluated from the system's perspective). I) Normalisation is mainly applied for two purposes: I.a) MAY - Normalisation to support interpretation: In support of the interpretation of the results of the study, normalisation is an optional step under ISO

European Commission – JRC, ILCD Handbook: General Guide for LCA (2010)


The decision whether to include normalisation in the interpretation has been made in scope chapter 6.7.7. I.b) MAY - Normalisation use in cut-off quantification: For quantification of the achieved completeness / cut-off, in a first step the indicator results for the different impact categories may be normalised by expressing them relative to a common reference, the normalisation basis (“normalisation”). [ISO+] The decision whether to include normalisation in the cut-off has been made in scope chapter 6.7.7. The specific normalisation basis has been identified in the scope chapter 6.7.6. II) SHALL - Calculate normalised LCIA results per impact category: If normalisation is applied, the "normalised LCIA results" shall be calculated by dividing the LCIA results by the normalisation basis. This shall be done separately for each impact category (for midpoint level approaches) or area of protection (for endpoint level approaches)


This shall be done separately for each impact category (for midpoint level approaches) or area of protection (for endpoint level approaches). Note that normalised results shall not directly be summed up across different impact categories as this would imply an even weighting of all impact categories. This is unless this even weighting is intended and identified explicitly as weighting when communicating the results. 8.4 Weighting (Refers to ISO 14044:2006 chapter 4.4.3.4) Introduction Weighting is an optional step under ISO. Weighting involves assigning distinct quantitative weights to all impact categories expressing their relative importance. If needed for the


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 8 Life Cycle Impact Assessment - calculating LCIA results interpretation, and if in accordance with the goal of the LCI/LCA study, a weighting of the normalised indicator results may be performed. Also to implement the cut-off criteria, the use of weighted and normalised LCIA results is used. Hence for this purpose, weighting is a required step under the ILCD for all kinds of deliverables of the LCI/LCA study. The decision about inclusion of weighting and the used weighting has been made and documented in the first scope definition; it is binding and shall not be changed later during the study (see chapter 6.7.7). Calculating weighted and normalised LCIA results In weighting, the (typically194 initially normalised) LCIA results for the different impact categories are each multiplied with a relative weighting factor


Comparison across impact topics The normalised and weighted LCIA results can subsequently also be summed up across all impact categories or areas-of-protection. Note that under ISO 14044:2006 weighting shall not be used in studies leading to comparative assertions intended to be disclosed to the public. Provisions: 8.4 Weighting Note that this provision applies to all types of deliverables of the study, while for unit process, partly terminated system, LCI results and LCIA results data sets as deliverables only if the use of normalised and weighted LCIA results has been selected to quantify the achieved completeness and precision (these need to be evaluated from the system's perspective)


I) Weighting is mainly applied for two purposes: I.a) MAY - Weighting to support interpretation: In support of the interpretation of the results of the study, as an additional, optional element one may perform a “weighting” or other valuation of the - method-wise normalised or not normalised - indicator results. The decision whether to include weighting in the interpretation has been made in scope chapter 6.7.7. I.b) MAY - Weighting use in cut-off quantification: For quantification of the achieved completeness / cut-off, as second195 step the normalised indicator results for the different impact categories may be weighted across the indicators (“weighting”). [ISO+] The decision whether to include weighting in the cut-off has been made in scope chapter 6.7.7. The specific weighting set has been identified in the scope chapter 6.7.6


[ISO+] The decision whether to include weighting in the cut-off has been made in scope chapter 6.7.7. The specific weighting set has been identified in the scope chapter 6.7.6. II) SHALL - Calculate weighted LCIA results per impact category: If weighting is applied, to obtain "weighted LCIA results", the (typically normalised) LCIA results shall be multiplied by the weighting set, separately for each impact category (for midpoint 194 Note that this is no free choice, but the chosen specific weighting method either requires a preceding normalisation or a preceding normalisation shall not be done. 195 Note that some weighting methods work without a separate, preceding normalisation, as the normalisation is part of the weighting step.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 8 Life Cycle Impact Assessment - calculating LCIA results level approaches and in case of having calculated category-wise endpoint results) or Area of protection (for endpoint results that cover each a whole area of protection). The resulting weighted LCIA results can be summed up across the impact categories or areas of protection, respectively. III) SHALL - No weighting in published comparative assertions: Weighting shall not be used in studies leading to comparative assertions intended to be disclosed to the public. Note that the setting or selection of weighting factors necessarily involves value choices.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 9 Life cycle interpretation 9 Life cycle interpretation (Refers to ISO 14044:2006 chapter 4.5) 9.1 Introduction and overview (Refers to ISO 14044:2006 chapter 4.5.1) The Interpretation phase of an LCA has two main purposes that fundamentally differ:  During the iterative steps of the LCA and for all kinds of deliverables, the interpretation phase serves to steer the work towards improving the Life Cycle Inventory model to meet the needs derived from the study goal.  If the iterative steps of the LCA have resulted in the final LCI model and results, and especially for comparative LCA studies (while partly also applicable to other types of studies), the interpretation phase serves to derive robust conclusions and - often - recommendations. In life cycle interpretation, the results of the life cycle assessment are appraised in order to answer questions posed in the goal definition


In life cycle interpretation, the results of the life cycle assessment are appraised in order to answer questions posed in the goal definition. The interpretation relates to the intended applications of the LCI/LCA study and is used to develop recommendations. The life cycle interpretation is the phase of the LCA where the results of the other phases are hence considered collectively and analysed in the light of the achieved accuracy, completeness and precision of the applied data, and the assumptions, which have been made throughout the LCI/LCA study. As said, in parallel to performing the LCI work this serves to improve the LCI model. If aimed at (e.g. in case of a comparative study or a weak-point analysis), the final outcome of the interpretation should be conclusions or recommendations, which are to respect the intentions and restrictions of the goal and scope definition of the LCI/LCA study


This especially relates to the appropriateness of the functional unit and the system boundaries, as well as the achieved overall data quality, in relation to the goal. The interpretation should present the results of the LCA in an understandable way and help the user of the LCI/LCA study appraise the robustness of the conclusions and understand any potential limitations of the LCI/LCA study. Some of the elements of the interpretation (namely completeness and sensitivity analysis, as well as potentially uncertainty analysis for the determination of precision) are hence also applied throughout the LCI/LCA study. This is done together with quality checks on the level of unit process data, LCI results and applying impact assessment as part of the iterative loops which are used in the drawing of the system boundaries and collection of inventory data (see chapter 4)


The last step of conclusions and recommendations is only done in the end of the study, if conclusions and recommendations are aimed at. The interpretation proceeds through three activities as schematically illustrated in Figure 25 and detailed in the subchapters of this chapter:  First, the significant issues (i.e. the key processes, parameters, assumptions and elementary flows) are identified (as discussed in chapter 9.2).  Then these issues are evaluated with regard to their sensitivity or influence on the overall results of the LCA. This includes and evaluation of the completeness and consistency with which the significant issues have been handled in the LCI/LCA study (chapter 9.3).


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 9 Life cycle interpretation Finally, the results of the evaluation are used in the formulation of conclusions and recommendations from the LCA study (chapter 9.4).  In the cases where the study involves comparisons of two or more systems, additional considerations are to be included in the interpretation (also chapter 9.4). Figure 25 The elements of the interpretation phase and their relations to other phases of the LCA and within the interpretation phase (from ISO 14044:2006, modified) 9.2 Identification of significant issues (Refers to ISO 14044:2006 chapter 4.5.2 and to aspects of 4.4.4) Overview The purpose of this first element of interpretation is to analyse and structure the results of earlier phases of the LCI/LCA study in order to identify the significant issues. There are two interrelated aspects of significant issues: Firstly, there are the main contributors to the LCIA results, i.e


There are two interrelated aspects of significant issues: Firstly, there are the main contributors to the LCIA results, i.e. the most relevant life cycle stages, processes and elementary flows, and the most relevant impact categories. They are important for the overall interpretation of the LCI/LCA study and for eventual recommendations. They are to be identified through a contribution analysis (also called gravity analysis), i.e. by quantifying, which contributor contributes how much to the total, resulting e.g. in stacked columns or the well-known pie charts. In the case of future scenario LCA, the contribution analysis is to be combined/build upon a scenario modelling and analysis. Secondly, there are the main choices that have the potential to influence the precision of the final results of the LCA


Secondly, there are the main choices that have the potential to influence the precision of the final results of the LCA. These can be methodological choices (including the LCI Direct applications: • Product development and improvement • Strategic planning • Public policy making • Marketing • Other Life Cycle Assessment framework Goal definition Scope definition Inventory analysis Impact assessment Goal definition Scope definition Inventory analysis Impact assessment Interpretation Conclusions, limitations, and recommendations Identification of significant issues Evaluation by: • Completeness check • Sensitivity check • Consistency check • Other checks


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 9 Life cycle interpretation modelling principles, and LCI method approaches applied, cut-off decisions and other system boundary settings), assumptions, foreground and background data used for deriving the process inventories, LCIA methods used for the impact assessment, as well as the optionally used normalisation and weighting factors. Significant choices are to be identified in a different way than the main contributors: by running the different possible choices as scenarios and comparing the scenario results. Contribution analysis (weak point analysis, gravity analysis) Several interests and applications can require to apply the contribution analysis:  Identify the need for further data collection or data quality improvement by quantifying the completeness of the inventory.  Focus further data collection efforts on the most contributing processes and individual elementary flow interventions


 Focus further data collection efforts on the most contributing processes and individual elementary flow interventions.  Focus efforts in ecodesign and product improvement / development on the most contributing processes and individual elementary flow interventions.  Communicate the share of internal vs. external contribution to the overall environmental impact in context of customer or stakeholder communication.  Contribute to internal quality control during the LCA work by investigating the qualitative and quantitative plausibility of the detailed outcome of the contribution analysis; this is part of the interim and final evaluation of the LCI/LCA study results. Depending on the drivers, inventory data-related significant issues are to be identified among whole life cycle stages, producer internal / external processes, groups of activities (e.g. transportation, energy production, services), key processes, and/or key elementary flows / interventions


transportation, energy production, services), key processes, and/or key elementary flows / interventions. If key processes of the system are parameterised, these parameters can equally be significant issues. The analysis is typically done on multiple levels, e.g. for LCIA results: firstly in relation to the individual elementary flows, secondly in relation to the individual impact categories on midpoint and/or category endpoints on endpoint level, and thirdly in relation to the overall (normalised and weighted) environmental impact. The third step is in general also called dominance analysis. In practice the contribution analysis is supported by professional LCA tools, or can be done by analysis of the inventory and LCIA result tables in spreadsheet software. Significant issues for unit processes and partly terminated systems On the level of a unit process, the most significant issues can only be identified for the elementary flows that are directly related to that process


This is because the inventories of any input products and subsequent waste management processes are not included in the unit process‟ inventory. To nevertheless be able to quantify which flows are the most significant ones for the analysed unit process, it is necessary to include the life cycle inventories of the named products and waste management processes before the contribution analysis is done. The above applies analogously for partly terminated systems data sets. Provisions: 9.2 Identification of significant issues This provision applies to all types of deliverables of the study, but for unit process, partly terminated systems, LCI results and LCIA results data sets as deliverables only to improve the data quality during the iterative loops of developing the LCI data or the system model. (Findings may also be included in an LCI study report.)


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 9 Life cycle interpretation I) SHALL - Identify significant issues: These can be among the following: I.a) Inventory items: Main contributing “key” life cycle stages, processes, product, waste and elementary flows, parameters. This part is also known as weak point analysis or gravity analysis. Use contribution analysis techniques. I.b) Impact categories: Main contributing “key” impact categories (only identifiable if weighting was applied). Use contribution analysis techniques. I.c) Modelling choices and method assumptions: Relevant modelling choices, such as applied allocation criteria / substitution approaches in the inventory analysis, assumptions made when collecting and modelling inventory data for key processes and flows, selecting secondary data, systematic choices on technological, geographical, and time-related representativeness, methodological consistency, extrapolations, etc


Use scenario analysis techniques. I.d) Commissioner and interested parties: The influence of the commissioner and interested parties on decisions in goal and scope definition, modelling choices, weighting sets and the like. Discuss influences on final results and recommendations. [ISO!] Note: For analysing the significant issues of unit processes and partly terminated systems, complete the system model as appropriate (e.g. cradle-to-gate) with a background system before the contribution analysis is done (see chapters 7.8). Focus the contribution analysis to the unit process / partly terminated system itself (i.e. the significant flows, assumptions, parameters, processes etc. within the original system boundary). Note: the "informative" annex B of ISO 14044:2006 provides a range of examples of life cycle interpretation, including but not only on the identification of significant issues


Note: the "informative" annex B of ISO 14044:2006 provides a range of examples of life cycle interpretation, including but not only on the identification of significant issues. 9.3 Evaluation (Refers to ISO 14044:2006 chapter 4.5.3) 9.3.1 Introduction and overview (Refers to ISO 14044:2006 chapter 4.5.3.1) Evaluation of final results The evaluation element is performed to establish the foundation for subsequently drawing the conclusions and provide recommendations during the interpretation of the LCI/LCA study results (see chapter 9.4). The evaluation is performed in close interaction with the identification of significant issues (see preceding chapter 9.2) in order to determine the reliability and robustness of the results. The evaluation builds upon the results of the earlier phases of the LCA and analyses the LCI/LCA study in an integrated perspective, i.e. based on the outcome of the inventory data collection, inventory modelling, and impact assessment


based on the outcome of the inventory data collection, inventory modelling, and impact assessment. It is done in accordance with the goal and scope of the LCI/LCA study, and its focus is on the significant issues identified among methodological choices and data. The evaluation involves:  completeness check (9.3.2),  sensitivity check in combination with scenario analysis and potentially uncertainty analysis (9.3.3), and  consistency check (9.3.4).


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 9 Life cycle interpretation The outcome of the evaluation is crucial to give strength to the conclusions and recommendations from the study, and it must therefore be presented in way which gives the commissioner and intended audience of the study a clear understanding of the outcome. Note that depending on the goal and scope of the LCI/LCA study, different steps of the evaluation may need to be applied. For example, it is only for comparisons between systems that comparative conclusions will be drawn. This is thus not the case when e.g. LCI results data sets are the deliverables of the LCI/LCA study and Environmental Product Declarations (EPD) are the intended applications. However, most steps of the evaluation are nevertheless always required, as non-comparative results such as e.g. LCI data sets may be foreseen to be used as background data for comparative questions on other systems


LCI data sets may be foreseen to be used as background data for comparative questions on other systems. To correctly inform subsequent data set users, the completeness and consistency of the data set‟s inventory is to be evaluated. Equally is the applicability of specific LCIA methods to be checked, by evaluating the assignment of the elementary flows to the applicable/supported impact models. Evaluation as part of the iterative steps of LCI/LCA study Using the same methods and approaches as for the final evaluation of the LCI/LCA study, the evaluation is also used during the development of the LCA to analyse the achieved completeness, accuracy, precision and consistency. It serves to identify needs for additional or better data as well as revision of assumptions made and other methodological choices


It serves to identify needs for additional or better data as well as revision of assumptions made and other methodological choices. 9.3.2 Completeness check (Refers to ISO 14044:2006 chapter 4.5.3.2) Overview Completeness checks on the inventory are performed in order to determine the degree to which it is complete and whether the cut-off criteria have been met. If the cut-off criteria are not (yet) met, additional or better data is to be used in order to satisfy the goal and scope of the LCA. When performing the completeness check, missing, but relevant LCIA factors and elementary flows are to be semi-quantitatively considered. Alternatively and if the cut-off criteria cannot be met, the goal and scope definition may have to be adjusted to accommodate the lack of completeness. This may however mean that the original questions of the goal cannot be answered any more or that developed data does not meet the aimed at quality


This may however mean that the original questions of the goal cannot be answered any more or that developed data does not meet the aimed at quality. The challenge of the completeness check, that was already mentioned earlier, is to overcome the seemingly paradox to judge the degree of completeness of the inventory while the absolute numbers of the complete inventory cannot be known. This problem is solved as described below. As a general rule, it is recommended to include as many elementary flows as possible in the inventory to allow the (internal or external) user to perform a detailed impact assessment and analysis. This is also advisable to be able to answer potential questions on possible missing flows that may come from reviewers or third parties (if the data is foreseen to be published/distributed)


This is also advisable to be able to answer potential questions on possible missing flows that may come from reviewers or third parties (if the data is foreseen to be published/distributed). As a minimum, all elementary flows of quantitative relevance to the overall environmental impact of the process or system, which are addressed in the impact assessment, should be included. It is important to understand that the % completeness achieved must not be misinterpreted that it would indicate the exact 100 % completeness. However does the achieved completeness indicate the approximate true value (Note that this value has a higher uncertainty, the lower the % of approximated completeness is.) Any difference in


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 9 Life cycle interpretation achieved completeness across compared alternatives must accordingly be considered when interpreting the results, drawing conclusions and giving recommendations: i.e. if one option has e.g. 95 % completeness and the other 90 %, that difference must be considered. Operationalising cut-off criteria during unit process development The overall cut-off criteria (e.g. "90 % completeness") were defined in the scope definition phase of the LCI/LCA study. Their translation into operational cut-off criteria during data collection of the individual unit process can be done using the following combined criteria:  For product flows: “mass” (of individual key chemical elements) AND “energy content196” AND “market value” (or “production/provision cost”). The market value is especially relevant for services, which often have no mass and no relevant energy content


The market value is especially relevant for services, which often have no mass and no relevant energy content.  For waste flows: “mass” (of individual key chemical elements) AND “energy content” AND “treatment cost”  For elementary flows: “mass” (of individual key chemical elements and only for the environmentally relevant flows, i.e. excluding not or less relevant flows such as e.g. incineration air consumed and waste steam leaving the process as emission to air) AND “energy content”  In addition, those emissions and wastes should be included that have a low mass or energy content and do not cause direct costs but are of known relevance for the respective type of process or industry. This is given, if the respective emission is regulated or to be reported for the respective process or a technically similar process or industry (also in other countries with comparably strict regulations, e.g. the U.S. or Japan or the EU)


the U.S. or Japan or the EU). Balances between input and output of these criteria and performed jointly across all flow types will help identifying relevant gaps or errors in by far most cases. While the finally achieved degree of completeness shall primarily be judged along the overall environmental impact or impact category by impact category, as detailed in chapter 6.6.3, the above steps help during the life cycle inventory work to efficiently complete the data with high quality data, given the practical restrictions. Note that for comparative assertions, the cut-off shall always be met also by mass and energy (as also required in ISO 14044). Before illustrating how this looks in practice, the 100 % reference needs to be identified: Approximating the 100 % value As a necessary, preceding step before the achieved completeness can be approximated, the 100 % value of the "complete" inventory and impact is to be approximated


It is seemingly a paradox to already initially know the final outcome, i.e. what is the 100 % of the flows in terms of chemical elements, energy content and costs, and of the inventory's overall environmental impact. In practice this issue can be reasonably addressed as follows: After modelling the system with all available data, for all missing information a "best approximation" value/flow is to be identified by expert judgment. This relates to all kinds of relevant missing information and data, especially:  kind and quantity of initially missing flow data, 196 This can be the lower or upper calorific value or - preferably from method perspective, but less practical - the exergy.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 9 Life cycle interpretation element composition and energy content of all flows that relevantly contribute to the total mass of the flows,  cost of all goods and services that relevantly contribute to the total production cost and production value  environmental impact of yet missing background data for consumed goods and services. Suitable approaches for identifying / quantifying the above are knowledge from sufficiently similar processes, expert judgement, and legal provisions (e.g. emission limits for related processes or industries, while these may be rather reasonable worst case estimates and need additional expert adjustment). Most problematic are qualitative gaps, i.e. lack of awareness of the occurrence of a flow. For emissions, legal provisions of any kind that aim at reporting, measuring, or reducing such emissions are a suitable means to detect their existence and potential relevance


For emissions, legal provisions of any kind that aim at reporting, measuring, or reducing such emissions are a suitable means to detect their existence and potential relevance. Also the existence of abatement technologies for certain emissions is a clear indication. Expert judgement based on process understanding is another means, also for qualitative gaps on consumables and services, which might also be detected by their cost but might not be easily attributable to the analysed process as handled e.g. on site level. Especially for missing environmental impact data, LCI data sets of similar goods or services can be used or average LCI data sets of the group of goods or services to which the respective product or waste flow belongs. If e.g. an unknown "Metal sheet" is used in a furniture manufacturing process of wooden writing desks, a mix of differently coated (e.g. powder, zinc) sheets of the typically used metals for the respective type of product or in that industry (e.g


powder, zinc) sheets of the typically used metals for the respective type of product or in that industry (e.g. 70 % steel, 30 % aluminium for writing desks) could be used. If also the amount of that sheet is unknown, the value (of its mass or area and thickness) could be approximated from knowing its function in the product and the products total mass, applying expert judgement (e.g. "connecting elements of wooden writing desks of each 40 kg total mass" could result in the estimate of 1 kg at 2 mm sheet thickness). Similarly a missing inventory for a "production plant for chemical X" would be approximated from similar production processes, scaling the inventory by the relative annual amount of production of the respective chemicals. If such information would be generally missing, an expert judgement of the mass of the main components of the chemical plant (e.g. stainless steel, construction steel, polymers, concrete) and their respective processing depths (e.g


stainless steel, construction steel, polymers, concrete) and their respective processing depths (e.g. tubes, profiles, precast, foil) could be obtained. Available LCI data sets can then be used to approximate the life cycle inventory of that plant and scale/relate it to its life time output of the analysed chemical. Note that in contrast to the subsequent step of identifying which flows should be priority for obtaining better quality data, here the most likely value ("best approximation") is to be used. Note also that in contrast to the data that should stay in the final inventory, for approximating the 100 % value also data of lower quality should be included, as long as their quality is not so low that they very substantially worsen the overall data quality. Note that when later reporting the inventory, the data of lower quality than "data estimate" is to be left out of the inventory, as it would otherwise lower the overall quality of the data set


Note that when later reporting the inventory, the data of lower quality than "data estimate" is to be left out of the inventory, as it would otherwise lower the overall quality of the data set. Depending on what has been decided in chapter 6.6.3 on whether the overall environmental impact is judged separately and for all of the included impact categories or jointly for all of them by including a normalisation and weighting step, the LCIA results or


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 9 Life cycle interpretation weighted LCIA results are calculated. This is the approximated 100 % value of overall environmental impact. It is argued that along these steps a reasonable approximation of the unknown 100 % value can be achieved, as it is good practice in industry197. If in the end, the true but unknown overall environmental impact value can be expected to be a few % higher or sometimes lower198 than the approximated 100 %. This should however very seldomly affect the validity of the work. This is due to the fact that even for very good and complete studies there are always a few remaining % of data uncertainty and a similar % lack of accuracy. Hence to actually achieve 100.0 % completeness compared to e.g. 97 % would not improve the overall quality of the results or the robustness of decision-support


Hence to actually achieve 100.0 % completeness compared to e.g. 97 % would not improve the overall quality of the results or the robustness of decision-support. To get an idea of how precise is the 100 % approximation, the share of data of different overall quality should be analysed, i.e. which share is of "high quality", "basic quality", and "data estimate": The higher the share of higher quality data is, the more precise is also the 100 % approximation and the more precise is the value that can be given for the achieved overall completeness. Judging the achieved degree of completeness along the operational criteria How does that look like in practice: In an example, the final cut-off criteria may be e.g. "90 % of the overall environmental impact". It would then be checked on level of the unit process whether the included flows of at least "data estimate" jointly make up at least 90 % of the unit process‟ environmentally relevant chemical elements‟ masses (e.g


of each “Carbon”, “Sulphur”, and “Nitrogen” for a "Fuel oil heating XY" process), 90 % of the unit process‟ energy (as lower or upper calorific values of all energy-containing flows), 90 % of the unit process‟ cost (e.g. production cost including waste treatment cost and production value/market price of all co-products of e.g. a manufacturing process). Note, that for the chemical elements‟ mass and energy this refers separately to input and output flows. For costs it relates to the total production cost on the one hand and total production value or market price on the other hand. The inclusion of specific emissions that might escape the previous steps but that are nevertheless relevant (e.g


The inclusion of specific emissions that might escape the previous steps but that are nevertheless relevant (e.g. among others particle emissions in the above fuel oil heating process, or dioxin emissions for certain scrap melting and waste incineration processes) can mostly be identified by including all legally regulated emissions for that or similar process types or are identified by expert judgement, drawing on know-how for these or similar processes. For these emissions no other, quantitative operational cut-off can be given, i.e. 197 Sometimes it is proposed to use economy wide or industry sector wide inventory data and break these down to single products' inventory data sets. This is meant to overcome the not 100% completeness of the process-based inventories. However, also these sector and economy wide data are not 100% complete. They are based on incomplete data from only a part of the (moreover only bigger) companies plus integrating other information sources


They are based on incomplete data from only a part of the (moreover only bigger) companies plus integrating other information sources. This data is extrapolated for the rest of the entire sector, using various assumptions and expert judgement. Also, the related life cycle model is based mostly on economic relationships among sectors instead of a specific process or supply-chain. This, and the allocation of the impacts across all products from the same sector, results in additional distortions. The resulting inventory data sets from economy or sector wide models can hence not be assumed to be more complete than process-based inventory data sets. In fact, given its methodinherent lack of accuracy and its uncertainty, this data can be expected to strongly overestimate or underestimate the true 100% value, depending on the specific case


In fact, given its methodinherent lack of accuracy and its uncertainty, this data can be expected to strongly overestimate or underestimate the true 100% value, depending on the specific case. It can be concluded that the 100% completeness of the inventory of a single process step can best be approximated by analysing this process step along an approach as described in the main text above. The completeness of the single process steps is then the most accurate basis for the completeness of the product's life cycle model. 198 It can be lower, if the lack of quality of the data that is used to approximate it, overestimates the 100% value.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 9 Life cycle interpretation their inclusion can be judged only when judging the achieved overall environmental impact, in the next step: Completeness of environmental impact To obtain the interim or finally achieved values of completeness ("cut-off"), the % coverage with data of at least "data estimate" quality is calculated. This uses the approximated 100 % value of the whole system model including data of lower quality as reference (using the "best approximation" information and data for still missing information and data); see above. Option to leave out negligible flows In addition, all processes and flows that can be judged to be quantitatively negligible from former experience or from using "reasonably worst case" approximation, can be entirely left out of the inventory. "Negligible" means here that such processes/flows make up together less than 10 % of the part of the share that is cut off


"Negligible" means here that such processes/flows make up together less than 10 % of the part of the share that is cut off. Example: The cut-off for one example system might be 95 %. E.g. 80 % of the overall results might be of "high quality" and "basic quality" and 15 % might be lower quality "data estimates", using the "best approximation" data. In that example, everything else can be entirely excluded as "negligible" if it together can be approximated / estimated to account for less than 10 % of 5 % (i.e. 0.5 %) of the total impact. This last provision allows to remove all negligible flows from the inventory. This is estimated to result in inventories of LCI results that are reduced by roughly 50 to 80 % of the inventory flows, easing quality control and interpretation. For transparency and communication reasons it is however recommended to leave them in


For transparency and communication reasons it is however recommended to leave them in. Provisions: 9.3.2 Completeness check This provision applies to all types of deliverables of the study, but for unit process, partly terminated systems, LCI results and LCIA results data sets as deliverables only to improve the data quality during the iterative loops of developing the LCI data or the system model. (Findings may also be included in an LCI study report.) I) SHALL - Evaluate LCI model completeness (cut-off): The cut-off rules as defined in the scope phase (see chapter 6.6.3) shall be systematically applied to ensure that the final data set inventory/ies meets the pre-defined or goal-derived data quality requirements (see chapter 6.9.2)


Evaluate the completeness of the inventory data in relation to the initially defined cut-off criteria in terms of: I.a) Process coverage: Coverage of all relevant processes in the system I.b) Elementary flow coverage: Coverage of all relevant elementary flows in the inventories for the processes of the system (and in particular the key processes identified under Significant issues – see chapter 9.2), that have characterisation factors for the relevant impact categories (according to the goal of the LCI/LCA study) I.c) Operationalise cut-off approximation: The cut-off criteria / approach and percentage as defined in the scope phase shall be used (see 6.6.3)


This may be operationalised using stepwise the following cut-off rules for flow properties, prechecking property by property the achieved completeness across all flow types and balancing the aggregated numbers in the inputs against those of the outputs: [ISO+] I.c.i) For product flows: “mass” (of individual key chemical elements), “energy content”, “market value” (or “production/provision cost”,


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 9 Life cycle interpretation especially for purchased services). I.c.ii) For waste flows: “mass” (of individual key chemical elements), “energy content”, “treatment cost”. I.c.iii) For elementary flows: “mass” (of individual key chemical elements and only for the environmentally relevant flows, i.e. excluding not or less relevant flows such as e.g. incineration air consumed and waste steam leaving the process as emission to air), “energy content”. I.d) Cut-off for comparative assertions: The cut-off shall always be met also by mass and energy, in addition to environmental impact. I.e) Additional relevance criteria for elementary and waste flows: Also those emissions and wastes should be include in the data collection that have a low mass and energy content but a known relevance for the respective type of processes or industry (using e.g. legal limits and expert judgement)


legal limits and expert judgement). [ISO+] I.f) Approximating the 100 % value: The 100 % reference of completeness may be approximated by using "best approximation" values for all initially missing information and data, using among others information from similar processes and expert judgement. This missing information and data can be especially: [ISO+] I.f.i) kind and quantity of initially missing flows, I.f.ii) element composition and energy content of all flows that relevantly contribute to the total mass of the flows, I.f.iii) cost of all goods and services that relevantly contribute to the total production cost and production value I.f.iv) environmental impact of yet missing background data sets for consumed goods and services


I.g) Estimating precision of 100 % value approximation: The precision of the 100 % approximation may be judged from analysing the share of the different quality levels of the data that make up the inventory: a higher share of low quality data also makes the 100 % approximation less precise. [ISO+] I.h) Completeness of impact: As last step, and using the quantitative cut-off value decided upon in chapter 6.6.3, approximate the achieved degree of completeness / cut-off. [ISO+] I.i) Leaving out negligible flows: It is an option to leave out negligible flows that jointly make up less than 10 % of the share of impact that is cut off (e.g. if the completeness is 95 %, 5 % are cut-off. 10 % of these 5 % are 0.5 % that are considered negligible.) It is recommended however to not leave them out. [ISO+] Note that the LCIA methods and (potentially) normalisation and weighting for use in defining the cut-off was decided in the scope phase, see chapter 6.7.7


[ISO+] Note that the LCIA methods and (potentially) normalisation and weighting for use in defining the cut-off was decided in the scope phase, see chapter 6.7.7. Note that for unit processes and partly terminated systems the completeness is to be judged in relation to the unit process and partly terminated system itself. I.e. any lack of completeness of other processes that were added exclusively to complete the system model for the completeness check shall be disregarded when quantifying the achieved completeness. II) SHOULD - Improve completeness, if needed: In the case of insufficient completeness, the inventory analysis (and sometimes the impact assessment) phases should be revisited to increase the degree of completeness. It is recommended to focus


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 9 Life cycle interpretation on the key life cycle stages, processes and flows identified as significant issues. This improvement of the LCI data is however to be started by potentially fine-tuning or revising goal and scope, i.e. with a complete iteration (see chapters 2.2.4 and 4, and related Figure 4 and Figure 5). III) SHALL - Report final completeness; potentially revise scope or goal: If the aimed at completeness has been achieved, or if it cannot be increased further, the finally achieved degree of completeness shall to be reported (as % degree of completeness / cut-off). For LCA studies, it shall be considered when later formulating the limitations in the conclusions and recommendations. If the aimed at or necessary completeness cannot be achieved, it shall be decided whether the scope or even the goal needs to be revised or re-defined


If the aimed at or necessary completeness cannot be achieved, it shall be decided whether the scope or even the goal needs to be revised or re-defined. 9.3.3 Sensitivity check (of achieved accuracy and precision) (Refers to ISO 14044:2006 chapter 4.5.3.3 and aspects of 4.4.4) The sensitivity check has the purpose to assess the reliability of the final results and – if included – of the conclusions and recommendations of the LCA study199. Expert judgement and previous experiences contribute to the sensitivity analysis. Scenario analysis and uncertainty calculations are the quantitative methods to support it (see annex 16). In the interpretation step the sensitivity analysis is used together with information about the uncertainties of significant issues among inventory data, impact assessment data and methodological assumptions and choices to assess the reliability of the final results and the conclusions and recommendations which are based on them (chapter 9.4)


As required under ISO 14044:2006, the evaluation element shall include interpretative statements based on detailed sensitivity analyses when an LCA is intended to be used in comparative assertions intended to be disclosed to the public. It is useful to structure the sensitivity check along the LCA phases “goal and scope”, “life cycle inventory”, and “life cycle impact assessment”: Goal and scope phase:  The sensitivity analysis is to check for limitations in the appropriateness of the scope choices, in relation to the goal of the study and for drawing conclusions and recommendations, especially the appropriate..


- identification of the system(s) to be studied; - identification of the function(s) and functional unit of the system or, in the case of comparative studies, the systems; - identification of the appropriate LCI modelling frameworks and method approaches to be applied - identification of the system boundary and quantification of the cut-off criteria; - selection of the included impact categories and applied LCIA methods; - identification of the interpretation approach to be used; 199 Note that ISO 14044 puts the process of verifying whether “... assumptions, methods and data ... are in accordance with the goal and scope definition ...“ into the definition of „Consistency check“, while they are (more plausible) applied in the chapter „Sensitivity check“, what is done here as well.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 9 Life cycle interpretation - identification of LCI data and data quality requirements, including the applicability of the inventory data with the selected LCIA methods; - selection of normalisation and weighting sets200, if included as optional elements; - kind of assumptions and value choices made and their relevance - identification of applicable limitations to the use and/or interpretation of the results; Regarding goal and scope issues, the sensitivity check can be done by calculating and comparing scenarios especially for different specific LCI method approaches to solve multifunctionality of processes201. For the other items it can be done by qualitative analysis and argumentation based on expert judgement and building on previous experiences


For the other items it can be done by qualitative analysis and argumentation based on expert judgement and building on previous experiences. Life cycle inventory phase:  The sensitivity analysis is to check for limitations in the appropriateness of the life cycle inventory work, in relation to the goal and scope of the study and for drawing conclusions and recommendations. This relates especially to the appropriate collection or selection of inventory data regarding ..


This relates especially to the appropriate collection or selection of inventory data regarding ... - their technological, geographical and time-related representativeness for the analysed system (especially for “key” processes”); - their completeness of the inventory in relation to the included and quantitatively relevant impact categories (especially for “key” processes”); - the precision of their inventory values and parameters, due to the stochastic uncertainty of the used raw data Regarding life cycle inventory issues this check is at least to be done on the sensitive issues that were identified in the preceding step (see chapter 9.2). The check can be done by joint scenario analysis and/or be accompanied by an uncertainty calculation (e.g. Monte-Carlo Simulation). Note again that uncertainty calculation can support an expert judgement while not substitute it, given the limitations of uncertainty calculations to reflect the true uncertainty


Note again that uncertainty calculation can support an expert judgement while not substitute it, given the limitations of uncertainty calculations to reflect the true uncertainty. The influence of data uncertainty for key issues can also be checked by allowing the data and parameters to vary within the limits given by the uncertainty estimates while modelling the system and comparing the results. 200 This includes the following: A) If normalisation is included as optional element: Limitations in especially the completeness and consistency across impact indicators but also the geographical and time-related representativeness of the normalisation data. Limitations in the compatibility with the chosen LCIA method and impact categories. Limitations regarding the appropriateness of the selected geographical or other reference of the normalisation data in relationship to the target audience and decision-context of the LCA work


Limitations regarding the appropriateness of the selected geographical or other reference of the normalisation data in relationship to the target audience and decision-context of the LCA work. B) If weighting is included as optional element: limitations regarding the chosen weighting level (i.e. midpoint or endpoint level), due to the different degree of precision of the LCIA results and different robustness of the weighting factors. Limitations regarding the appropriateness of the weighting approach (e.g. scientific panel, distance-to-target, policy panel, stakeholder-panel, etc.) in view of the decision-context and target audience of the LCA work results. 201 This means within the range of the methodological provisions of this document, e.g. in cases where different physical causalities may be applicable as allocation criteria or where different permissible options exist for system expansion / substitution.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 9 Life cycle interpretation Life cycle impact assessment phase202:  The sensitivity analysis is to check for limitations in the appropriateness of the LCIA work, in relation to the goal and scope of the study and for drawing conclusions and recommendations. This relates especially to the - appropriate selection (or if applicable: development, variation/extension) of the LCIA methods and their correct and complete application to the inventory - appropriate selection and correct application of normalisation and weighting factors (if included) - achieved precision of the LCIA results, if such are the deliverable of the LCA study or basis for a subsequent interpretation and conclusions drawn


In relation to the latter, due attention shall be paid in the interpretation to the fact that the uncertainty of the characterisation factors varies between the impact categories reflecting the state of the art in terms of modelling of the underlying impact pathway, and also the availability and quality of substance data applied in calculation of the characterisation factors for individual substances. The chemical-related midpoint level impact categories addressing human toxicity and ecotoxicity are thus accompanied by considerably larger uncertainties than the often energy-conversion related midpoint level categories addressing e.g. acidification, photochemical ozone formation or global warming impacts. Regarding LCIA, the sensitivity check can be done by a scenario analysis, applying different permissible LCIA methods. This can be accompanied by an uncertainty calculation on LCIA results level


Regarding LCIA, the sensitivity check can be done by a scenario analysis, applying different permissible LCIA methods. This can be accompanied by an uncertainty calculation on LCIA results level. Note that such can only support an expert judgement while not substitute it, given the limitations of uncertainty calculations to reflect the true uncertainty. Regarding normalisation and weighting as optional elements of the LCIA phase, the sensitivity check can combine scenarios applying different permissible weighting sets (potentially including with uncertainty calculations) on the level of the normalised LCIA results. Use of sensitivity analysis during iterative LCI/LCA study The combination of sensitivity analysis helps in identifying focus points for improved inventory data collection or impact assessment


Use of sensitivity analysis during iterative LCI/LCA study The combination of sensitivity analysis helps in identifying focus points for improved inventory data collection or impact assessment. Data, which has a strong influence on the final results of the LCI/LCA study may nevertheless not require further data collection effort if the representativeness and completeness of the data is high and its uncertainty low. Also data with a high uncertainty need not be a focus point for improvement if the sensitivity/relevance of this data is very low. The focus point for improvement of data quality should be data with both a strong influence on the overall results and a high uncertainty (see Figure 26). If such data cannot be improved, the result is a low overall quality of the results which is to be documented. If the precision is insufficient to meet the requirements from the intended application of the results, it may be necessary to revise the goal of the LCI/LCA study


If the precision is insufficient to meet the requirements from the intended application of the results, it may be necessary to revise the goal of the LCI/LCA study. 202 A number of the LCIA-related issues are to be addressed by the developers of the LCIA methods, and documented concisely with the methods as input to the LCA practitioner: A) Limitations in the methodological appropriateness and consistency of the LCIA method in relation to the represented midpoint level impact potential or endpoint damage. B) Limitations in the geographical, time-related and area-of-protection related representativeness of the LCIA method. C) Limitations in the precision of the impact factors, due to the stochastic uncertainty of the used raw data, related to among others substance properties, transport and transfer coefficients, exposure pathway factors, effect factors etc.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 9 Life cycle interpretation The second priority for improvement of data quality is the data that stands in between, i.e. showing both high sensitivity or significance and medium uncertainty or showing both high uncertainty and medium sensitivity. Figure 26 Focussing efforts on key data. In the iterative loops, main focus is on the key data with lack of quality (i.e. limited representativeness and consistency, high uncertainty, low completeness) paired with high sensitivity or significance. Due to the need for an iterative approach in LCA, sensitivity analysis hence used as an integrated element (with a steering function) in the iteration loops incorporating inventory data collection, impact assessment and system boundary setting for the system. The findings from these earlier sensitivity analyses are used as starting point for the sensitivity check of the interpretation


The findings from these earlier sensitivity analyses are used as starting point for the sensitivity check of the interpretation. Provisions: 9.3.3 Sensitivity check (of accuracy and precision) This provision applies to all types of deliverables of the study, but for unit process, partly terminated systems, LCI results and LCIA results data sets as deliverables only to improve the data quality during the iterative loops of developing the LCI data or the system model. (Findings may also be included in an LCI study report.) I) SHALL - Check sensitivity of results: Check to what extent the accuracy and precision of the overall results meets the requirements posed by the intended applications


Aim at improving it to the required level, as follows: I.a) Sensitivity of significant issues: Identify the most sensitive among the significant issues identified earlier (chapter 9.2) and analyse the sensitivity of these for the overall results, along with their stochastic and systematic uncertainty estimates. The outcome is determining for the accuracy and precision of the overall results and the strength of the conclusions, which can be drawn from the LCI/LCA study and must be reported together with these. Be aware that calculated uncertainty figures may not include the often determining systematic uncertainties caused by model assumptions, data gaps, and lack of accuracy. Lack of quality Sensitivity / significance Low priority High priority (key data) No priority Low priority (key data)


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 9 Life cycle interpretation I.a.i) Sensitivity of LCI items: Evaluate the sensitivity of the LCIA results (or weighted LCIA results, if applied) to key flows, process parameter settings, flow properties, and other data items such as recyclability, lifetime of goods, duration of services steps, and the like. Assess how sensitive inventory items influence the data representativeness, and precision. [ISO!] I.a.ii) Sensitivity of LCIA factors: Evaluate the sensitivity of the LCIA results (or weighted LCIA results, if applied) considering the often widely differing uncertainty of the results due to uncertainties in the impact assessment (e.g. Human toxicity, Ecotoxicity etc. with high uncertainties and Global warming, Acidification, etc. with lower uncertainty)


Human toxicity, Ecotoxicity etc. with high uncertainties and Global warming, Acidification, etc. with lower uncertainty). [ISO!] I.a.iii) Sensitivity of modelling choices and assumptions: Evaluate the sensitivity of the LCIA results (or weighted LCIA results, if applied) to different modelling choices and method assumptions ("method issues"), e.g. quantitative and qualitative aspects of the functional unit, superseded processes, allocation criteria, etc. [ISO!] I.b) Improve robustness of sensitive issues data, parameters, impact factors, assumptions, etc. as possible: In the case of lack of quality for some of the significant issues, revisit the inventory analysis and/or the impact assessment phases to improve the concerned data (for data issues), impact factors (for LCIA issues), or try to qualify and discuss the sensitive assumption or choice (for method issues)


As for data completeness, also the improvement of the LCI data precision is however to be started by potentially fine-tuning or revising goal and scope, i.e. with a complete iteration (see chapters 2.2.4 and 4). I.c) Report final achievements; potentially revise scope or goal: If the certainty of key issues meets the needs, or if it cannot be reduced to obtain the accuracy and precision that is required by the application of the LCI/LCA study, it shall be decided whether the scope or even the goal needs to be revised or re-defined. This shall be reported and for LCA studies later be considered when formulating the limitations in the conclusions and recommendations from the LCA (chapter 9.4). 9.3.4 Consistency check (Refers to ISO 14044:2006 chapter 4.5.3.4) The consistency check is performed to investigate whether the assumptions, methods, and data have been applied consistently throughout the LCI/LCA study203


The consistency check applies both to the life cycle of an analysed system and between compared systems. Methodological issues of relevance are especially the LCI modelling frameworks (i.e. attributional or consequential) and approaches (i.e. allocation criteria and selection of substituted systems), but also setting of system boundaries, extrapolations of data, the consistent application of the impact assessment, and other assumptions. 203 Note that ISO 14044 puts the process of verifying whether “... assumptions, methods and data ... are in accordance with the goal and scope definition ...“ into the definition of „Consistency check“, while they are (more plausible) applied in the chapter „Sensitivity check“, what is done here as well.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 9 Life cycle interpretation Inventory data issues of relevance concern the consistency of the time-related, geographical, and technological representativeness of the data, the appropriateness of the chosen unit process or LCI results to represent processes in the foreground and background system, and the completeness and precision of the data. Impact assessment issues of relevance are the consistent application of the LCIA elements, including – if applied – normalisation and weighting factors. Regarding the interrelationship of LCI data and LCIA methods this relates to the consistency of spatially and time-related differentiation of inventory data and corresponding impact factors


Regarding the interrelationship of LCI data and LCIA methods this relates to the consistency of spatially and time-related differentiation of inventory data and corresponding impact factors. Provisions: 9.3.4 Consistency check These provisions applies to all types of deliverables of the study, but for unit process data sets as deliverable only to improve the data quality during the iterative loops of developing the LCI data or the system model. (Findings may also be included in an LCI study report.) For partly terminated systems, LCI results and LCIA results data sets they serve in addition to ensure method consistency across the processes of the model. For LCA studies, they serve in addition to ensure method consistency across the models of the compared systems. I) SHALL - Data quality sufficiently consistent?: Check whether any differences in data quality per se (i.e


I) SHALL - Data quality sufficiently consistent?: Check whether any differences in data quality per se (i.e. accuracy, completeness, and precision) and in the selected data sources for the different processes in the system(s) are consistent with the goal and scope of the study. This is especially relevant for comparative studies. II) SHALL - Method choices consistent?: Check whether all methodological choices (e.g. LCI modelling principles, allocation criteria or system expansion / substitution approach, system boundary, etc.) are consistent with the goal and scope of the study including the intended applications and target audience. This shall be judged by checking whether the method provisions have been met that are given in relation to the applicable Situation A, B, or C1 / C2. [ISO!] Note that method consistency applies on both unit process level (i.e. consistent approach to develop unit process from raw data) and system level (i.e. consistently modelling the system)


[ISO!] Note that method consistency applies on both unit process level (i.e. consistent approach to develop unit process from raw data) and system level (i.e. consistently modelling the system). This aspect is especially relevant when combining data from different sources. III) SHALL - Consistent impact assessment?: Check whether the steps of impact assessment (including normalisation and weighting, if included) have been consistently applied and in line with goal and scope. IV) SHALL - Evaluate relevance of inconsistencies: Evaluate the relevance / significance of any identified inconsistencies (as above) for the results and document them, including when reporting the achieved method consistency and appropriateness. For LCA studies additionally consider these findings when drawing conclusions or recommendations from the results


For LCA studies additionally consider these findings when drawing conclusions or recommendations from the results. 9.4 Conclusions, limitations, and recommendations (Refers to ISO 14044:2006 chapter 4.5.4) Overview Integrating the outcome of the other elements of the interpretation phase, and drawing on the main findings from the earlier phases of the LCA, the final element of the interpretation is to draw conclusions and identify limitations of the LCA, and to develop recommendations for


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 9 Life cycle interpretation the intended audience in accordance with the goal definition and the intended applications of the results. Drawing conclusions The conclusions should be drawn in an iterative way: Based on the identification of significant issues (chapter 9.2) and the evaluation of these for completeness, sensitivity and consistency (chapter 9.3), preliminary conclusions can be drawn. Conclusions say whether the questions that were posed in the formulation of the goal definition can be answered by the LCA, i.e. whether significant differences exist between alternatives, which role the various sensitive issues play for such differences, and the like. An example e.g. for the illustrative goal question: “which of the two selected cleaning solutions for X has the lower environmental impacts” as the starting point of a comparative study of cleaning X by machine vs


for the illustrative goal question: “which of the two selected cleaning solutions for X has the lower environmental impacts” as the starting point of a comparative study of cleaning X by machine vs. cleaning X by hand it might be concluded: significant differences exist, but only for some of the relevant scenarios of user behaviour for manual cleaning and the energy-efficiency of the cleaning machine. The main factors of manual cleaning are the used water temperature and amount (depending on how often water is exchanged and whether final rinsing is done with running water). It is then checked whether the preliminary conclusions are in accordance with the requirements and limitations of the goal and scope phase, the limitations of the life cycle inventory phase and the limitations of the life cycle impact assessment phase


The most frequently outstanding limitations of being able to draw significant conclusions (where such would in theory be possible, as real differences exist) are:  the system boundary / cut-off settings (and that they have been actually met by the LCI data and model),  the achieved LCI data quality and consistency, as required by the goal,  the uncertainty of the LCIA methods,  specific predefined assumptions of the goal phase,  and for the given case relevant other, specific methodological and study limitations. If the conclusions are consistent with the requirements, they can be reported as final conclusions, otherwise they must be re-formulated and checked again. Dealing with limitations Any limitations of the study within the given goal and scope of the LCA study must be listed. Such can be e.g


Dealing with limitations Any limitations of the study within the given goal and scope of the LCA study must be listed. Such can be e.g. a limited completeness of elementary flows with relevance to relevant impact categories, or a limited time-representativeness, or pre-selection of climate change impacts only for carbon footprint studies, or methodological inconsistencies such as e.g. between some of the background data with the rest of the system, etc. It is then to be evaluated for each of them the type and magnitude of consequences these have for the conclusions and intended applications


It is then to be evaluated for each of them the type and magnitude of consequences these have for the conclusions and intended applications. Interpretation for comparative studies In studies that involve a comparison of systems (whether disclosed to the public or not), the interpretation has to consider a few additional points to ensure fair and relevant conclusions from the study:  Significant issues must be determined for each of the systems, and special attention is to be given to issues that differ between the systems and that have the potential to


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 9 Life cycle interpretation change the conclusions of the comparison. Such differences need to be eliminated if possible or otherwise fully considered in the formulation of conclusions.  If an uncertainty analysis is performed to investigate whether the difference between two systems is statistically significant, the analysis should be performed on the difference between the systems (i.e. one system minus the other), taking into account potential co-variance between processes of the two systems (e.g. processes which are the same) as far as possible given confidentiality restrictions regarding the access to included processes


processes which are the same) as far as possible given confidentiality restrictions regarding the access to included processes.  The important consistency check addresses consistent treatment of the key issues in the different systems and is fundamental to ensure a fair comparison: - Are the compared systems sufficiently equivalent? - Are differences in the quality of inventory data between different systems acceptably small, considering the relative importance of the processes in the system, and are the differences consistent with the goal and scope of the study? (If e.g


one study is based on specific and recent data with a high degree of representativeness for all the key processes while the other uses extrapolation from literature data, there is a bias in the inventory data which can make a comparison invalid.) - Have the LCI modelling frameworks, allocation rules and system boundary setting been consistently applied to all compared systems (including in the background data)? - Has the impact assessment been performed consistently for the systems, have the relevant impact categories been included for all systems, and have the impacts been calculated in the same way and with the same degree of completeness of elementary flows for all the systems? These are very important issues, and if they differ substantially between the systems, it can strongly bias the comparison and easily make it invalid


When an LCA is intended to be used in comparative assertions intended to be disclosed to the public, the ISO 14044:2006 standard requires in addition that the evaluation element includes interpretative statements based on careful sensitivity analyses. It is emphasized in the standard, that the inability of a sensitivity check to find significant differences between different studied alternatives does not automatically lead to the conclusion that such differences do not exist, but rather that the study is not able to show them in a significant way. At the same time, insignificant differences should be taken as what they are: insignificant; there is not always a clear preference for one or the other system, and this is also a valid outcome of an LCA study


Deriving recommendations Recommendations based on the final conclusions of the LCA study must be logical and be reasonable and plausible founded in the conclusions and strictly relate to the intended applications as defined in the goal of the study. Recommendations can be (always relating to the goal of the study) e.g.:


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 9 Life cycle interpretation - to focus product improvement on one or more specific process(es) or specific emission(s) that contribute main shares to the overall impact and have a relevant potential for improvement204, - on the superiority of one product over others that quantitatively and qualitatively fulfil sufficiently equivalent function(s), or - the lack of significant differences among a group of products that fulfil the same functions, - to change a supplier towards a supplier with less impacting own production or supply-chain205, - to improve the user manual by advising product users of how to easily lower the overall environmental impacts of the analysed product, - to stimulate the development of certain technology families (or raw material bases, etc.) by political or tax measures or R&D investment, - etc


Note that other applications beyond the ones covered in this guidance document (e.g. identifying ecolabel criteria or ecodesign indicators) may require additional steps, drawing on the deliverables of the LCA potentially including any conclusions and recommendations. Frequent errors: Inappropriate results interpretation in case of insignificant differences There are two, opposite risks when finding that compared alternative products do not differ significantly:  Firstly, a over-interpretation of the result: - exaggerating small or insignificant differences - drawing general conclusions and recommendations from specific case studies - putting to high confidence on differences between compared systems based on results of uncertainty analysis alone, that are only partially cover the full uncertainty of the results and do not include their accuracy


 Secondly, the risk of inappropriately claiming equality of compared alternatives, based on unbalanced or poor quality data that result in insignificance of differences. To avoid this, the reason for insignificance of differences between compared systems is to be stated together with the outcome of the study. An imbalance in the available data, methods applied etc. cannot be used to conclude that no difference exist between the two compared systems. The same applies analogously if the data situation is balanced by for both systems but at a low data quality level. 204 Note that such „product internal comparisons“ are formally also product comparisons and – especially in case of publication – the additional requirements for comparative assertions disclosed to the public are to be met also here. 205 Note that this touches on the issue of attributional and consequential modelling.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 9 Life cycle interpretation Comparative studies on not objectively comparable alternatives As explained in chapter 6.10.3, comparative studies may be performed on systems where the comparability cannot be done objectively (other than e.g. for bulk chemicals) but is to be judged by the individual consumer (e.g. for many personal services). The results and recommendations of such comparative studies shall hence be presented with the explicit statement that comparability is not assumed per se, but lies with the individual preference and judgement. Avoiding misinterpretation To avoid misinterpretations by the target audience any relevant limitations are to be given jointly with the recommendations


Avoiding misinterpretation To avoid misinterpretations by the target audience any relevant limitations are to be given jointly with the recommendations. It must be avoided as far as possible that the recommendations can be misinterpreted by the addressees of the LCA study beyond the scope of the specific LCA study and beyond what is supported by the outcome of the LCA including accounting for any limitations. This includes that an eventual limited technical or methodological understanding of the addressees must be accounted for. A compilation of aspects to avoid misleading interpretation is given in annex 15.3. Provisions: 9.4 Conclusions, limitations, and recommendations Note the limitations for Situation C1 and C2 studies in their use for direct decision support. These provisions apply only to comparative and non-comparative LCA studies


These provisions apply only to comparative and non-comparative LCA studies. I) SHALL - Analyse the results from a system's perspective: Separately analyse and jointly discuss the results obtained in the main system(s) model(s) and - if performed - with the corresponding reasonably worst and best case assumption scenarios and possibly further assumption scenarios. Integrate the results of any potentially performed uncertainty calculations into the analysis. [ISO!] I.a) Items that require special or separate analysis: I.a.i) Non-generic LCIA: Separately analyse and jointly discuss the results obtained with the default LCIA methods and those obtained including any potential additional or modified / non-generic (e.g. spatially or otherwise differentiated) LCIA methods. I.a.ii) Long-term emissions: Separately analyse and jointly discuss the results for interventions within the first 100 years from the time of the study and those beyond that time limit


I.a.ii) Long-term emissions: Separately analyse and jointly discuss the results for interventions within the first 100 years from the time of the study and those beyond that time limit. I.a.iii) Carbon storage and delayed emissions: Only if such is included in line with an explicit goal requirement: Separately analyse and jointly discuss the results including and excluding carbon storage and delayed emissions / reuse/recycling/reuse credits. I.b) Draw conclusions, if foreseen: Take into account the findings of the earlier elements of the interpretation phase. Draw conclusions in accordance with the goal defined for the LCA study and with the definitions of the scope, in particular those related to data quality requirements, and with the predefined assumptions and known limitations in the methodology and its application in the LCA. Consider all assumptions and related limitations that were noted down in the course of the study


Consider all assumptions and related limitations that were noted down in the course of the study. I.c) Address impacts outside the LCA scope, if any: Name any potential or actual


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 9 Life cycle interpretation effects on the three areas of protection that are based on other mechanisms than those covered by LCA (e.g. accidents, direct application of products to humans, etc.) and that are considered relevant by the interested parties. Clarify that these are outside the scope of LCA. Note that within the ILCD Handbook, not quantified effects outside the scope of LCA cannot be explicitly or implicitly assessed regarding their relevance in comparison to the LCA results206. I.d) Conclusions for comparisons: Differences in data quality and methodological choices between compared systems shall be consistent with the goal and scope of the study, especially (see also chapter 6.10): I.d.i) The functional unit of the compared alternatives shall be sufficiently similar to allow for comparisons, especially in view of stakeholders and potential users


I.d.ii) The setting of system boundaries shall be consistently applied to all systems. I.d.iii) The inventory data should be of comparable quality (i.e. accuracy, completeness, precision, methodological consistency) for all compared alternatives. I.d.iv) The steps of impact assessment shall be consistently applied for all systems. I.d.v) The significance of any above identified inconsistencies to the results of the comparison shall be evaluated and considered when drawing conclusions and giving recommendations from the results. II) SHALL - Recommend strictly based on conclusions and limitations: II.a) Base any recommendations made in the LCA study exclusively on these conclusions and respecting the limitations. Derive recommendations unambiguously and in a stepwise logical and reasonable consequence of the conclusions. Do so in accordance with the defined goal of the LCA study and specially the intended applications and target audience


Do so in accordance with the defined goal of the LCA study and specially the intended applications and target audience. II.b) Recommendations shall be made in a conservative way, only based on significant findings. Any relevant limitations found during the study are to be stated explicitly and clearly in the key message of the LCA study including in the executive summary. [ISO!] II.c) Special care must be taken to avoid misinterpretations also by a non-technical audience, to avoid interpretation beyond the scope of the LCA study and beyond what is supported by its outcome. II.d) Equality of compared alternatives shall not be stated, unless it has been shown to be significant: the lack of significant differences alone shall not be misinterpreted as equality of the analysed options. It shall only be stated that with the given data restrictions and/or uncertainties or other causes no significant differences could be identified


It shall only be stated that with the given data restrictions and/or uncertainties or other causes no significant differences could be identified. [ISO!] 206 Effects outside the scope of LCA may be - if available and quantified in a comparable manner (e.g. quantitatively related to the functional unit, considering the whole life cycle etc.) - integrated with LCA results in an additional evaluation and report beyond the scope of LCA and outside the scope of the ILCD. This should consider the relative accuracy and precision of the different approaches and effects.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 9 Life cycle interpretation III) SHALL - Comparisons of systems with dominant subjective preference: The results and recommendations of comparative studies on not objectively comparable alternatives (e.g. personal services, fashion items, jewellery) shall be presented with the explicit statement that comparability is not assumed per se, but lies with the individual preference and judgement. [ISO!] IV) SHALL - Conclusions on basket-of-product type of studies: For studies that analyse several processes or systems in a non-competitive manner, i.e. processes / systems that perform clearly different functions (e.g. basket-of-products, identifying priority products) it shall be clearly reported that no comparability exists in terms of preferability among the processes / systems


basket-of-products, identifying priority products) it shall be clearly reported that no comparability exists in terms of preferability among the processes / systems. Note: Annex 15.3 gives an illustrative example on avoiding misleading goal and scope definition and results interpretation for comparative studies.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 10 Reporting 10 Reporting (Refers to ISO 14044:2006 chapter 5) 10.1 Introduction and overview The results and conclusions of the LCI/LCA study shall be completely and accurately reported without bias to the intended audience. The results, data, methods, assumptions and limitations shall be transparent and presented in sufficient detail to allow the reader to comprehend the complexities and trade-offs inherent in the LCA. The report shall also allow the results and interpretation to be used in a manner consistent with the goals of the study. The needs of different audiences should be recognized and addressed when presenting or disseminating the study. Target audiences can be internal, (defined) external, or public, and technical or non-technical


Target audiences can be internal, (defined) external, or public, and technical or non-technical. These audiences can include companies, trade associations, government agencies, environmental groups, scientific/technical communities, and other non-government organizations, as well as the general public / consumers. Communication in the public domain is especially critical because the risks of misinterpretation are heightened when LCA-derived information is provided to audiences not familiar with the complexity of the methodology and related limitations that may apply. Good reporting of LCI and LCA studies provides the relevant project details, the process followed, approaches and methods applied, and results produced. This is essential to ensure reproducibility of the results and to provide the required information to reviewers to judge the quality of the results and appropriateness of conclusions and recommendations (if included)


The complete reporting should also contain the data used and should ensure transparency and consistency of all the methodologies and data employed. It should constitute the primary input to the scientific/technical audience and be a base from which summary reports to other target audiences could be prepared. These latter summaries need to be tailored to the recipient requirements, labelled as summaries only, and include appropriate reference to the primary report and related review reports in order to ensure that they are not taken out of context. Confidentiality interests around sensitive or proprietary information and data are to be met, while confidential access to at least the reviewers is to be granted to support the review of the data set and/or report. Separate, complementary confidential reports can serve this purpose


Separate, complementary confidential reports can serve this purpose. 10.2 Reporting principles (Refers to ISO 14044:2006 chapter 5.1.1) Reports and data sets The form and levels of reporting depends primarily on three factors:  the type of deliverable(s) of the study,  the purpose and intended applications of the study and report, and  the intended target audience (especially technical or non-technical and internal or thirdparty/public).


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 10 Reporting Reporting LCIA results Wherever LCIA results are published in a report or data set, for transparency reasons this is to be accompanied by the LCI results. In the case of normalised or weighted LCIA results, the results of previous steps (classification and characterisation) are equally to be reported. For the same reason, characterisation results at endpoint (damage) level are to be supplemented by midpoint level impact category results, as well as the LCI results. Confidentiality In the case data or information (e.g. on technologies, catalysts, ingredients) cannot be reported for confidentiality or proprietary reasons, this information can be documented in a separate confidential report that does not need to be made available externally, except for foreseen critical reviewers under confidentiality


The kind of information documented in this confidential report shall be named in the detailed report, if any. Reporting of revised goal and /or scope items In some cases, the goal and the scope of the LCI/LCA study may need to be revised due to unforeseen limitations, constraints or as a result of additional information. The final documentation of the LCI/LCA study has to reflect this, including the consequence for completeness, precision, application fields, etc. Provisions: 10.2 Reporting principles Fully applicable to all types of deliverables, implicitly differentiated. I) SHALL - Report complete and unbiased: Results and conclusions of the LCI or LCA study shall be completely and accurately reported without bias to the intended audience. II) SHALL - Use SI units: Per default the Système international d'unités (SI) units shall be used for reporting


II) SHALL - Use SI units: Per default the Système international d'unités (SI) units shall be used for reporting. III) SHALL - Reproducibility and target audience to guide reporting: Results, data, methods, assumptions and limitations shall be transparent and presented in sufficient detail to allow the reader to comprehend the complexities and trade-offs inherent in the study and LCA in general. Reporting of technical details shall be guided along the aim to ensure an as good as possible reproducibility of the results and of any conclusions and recommendations (if included). (On reporting of confidential or proprietary information see more below). Consider the technical and LCA methodology understanding of the target audience. IV) SHALL - Reporting LCIA results: Depending on the intended applications, the LCIA results may also be reported in the study report or data set


IV) SHALL - Reporting LCIA results: Depending on the intended applications, the LCIA results may also be reported in the study report or data set. If done, this shall meet the following requirements: [ISO!] IV.a) The intended way of reporting LCIA results was identified in the scope definition in accordance with the intended application of the LCI/LCA study and any prescription given in the goal definition. IV.b) For transparency reasons, the LCIA results shall be published jointly with the LCI results. In the case of normalised or weighted LCIA results the previous steps (classification and characterisation) shall equally be reported. IV.c) Impact assessment results at endpoint (damage) level shall be supplemented by


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 10 Reporting midpoint level impact category results (unless the endpoint LCIA method does not have a midpoint interim step) and also by the LCI results. Note that if the study is intended to support a comparative assertion to be disclosed to the public, no form of numerical, value-based weighting of the indicator results is permitted. 10.3 Three levels of reporting requirements (Refers to ISO 14044:2006 chapters 5.1.2, 5.2, and 5.3) In accordance with the ISO 14044:2006 standard, this handbook operates with three levels of the classical reporting with different (increasing) requirements. These relate to both project reports and data set files


These relate to both project reports and data set files. 10.3.1 Report for internal use (No corresponding ISO 14044:2006 chapter) The report is for internal use only and not intended for disclosure to any external party outside the company or institution that has commissioned or (co)financed the study or performed the LCA work. Examples could be studies for identification of internal improvement potentials and focus points in product development. No formal provisions are made for internal reports, of course. In order to provide appropriate and robust decision support, it is recommended to closely orient to the reporting requirements for third-party reports. 10.3.2 Third party report (Refers to ISO 14044:2006 chapters 5.1.2 and 5.2) The report is intended to document and/or communicate the results of the LCA to a third party (i.e. an interested party other than the commissioner or the LCA practitioner performing the study)


an interested party other than the commissioner or the LCA practitioner performing the study). Regardless of the form of communication, a third-party report must be prepared as a reference document and documentation of the study. It is not required to include confidential information that however needs to be available for reviewers under confidentiality agreement, and would be documented separately or as part of the report for internal use. The detailed aspects that shall be covered in the third-party report (and/or the confidential report as described more above and if such is prepared) are provided in the "Provisions" of this chapter and are not repeated here. Third-party reports should have an Executive summary for non-technical audience. For LCI data sets, a well documented, ILCD formatted data set can be the third-party report, if completed with the relevant background documents (e.g


For LCI data sets, a well documented, ILCD formatted data set can be the third-party report, if completed with the relevant background documents (e.g. more extensive method reports such as the ILCD Handbook, reports on data collection procedures, data sources used, review report(s), applied LCIA methods and to normalisation and weighting sets, and others, as needed to meet the requirements listed above). The annex serves to document elements that would inappropriately interrupt the reading flow of the main part of the report, and are also of a more detailed or tabular technical nature and for reference. It should include:  Questionnaire/ data collection template and raw data


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 10 Reporting List of all assumptions207 (It is recommended that these include those assumptions that have been shown to be irrelevant).  Full LCI results 10.3.3 Report on comparative studies to be disclosed to the public (Refers to ISO 14044:2006 chapter 5.3) The study involves a comparison of products and the results are intended to be disclosed to the public. This may or may not involve concluding the superiority of one product (or equality of the analysed products), i.e. it can be a “comparative assertion disclosed to the public” or a non-assertive comparative study that shall be treated the same as a comparative assertion.). In addition to the third party report, additional requirements apply. Note that it shall include an Executive summary for non-technical audience


In addition to the third party report, additional requirements apply. Note that it shall include an Executive summary for non-technical audience. The detailed aspects that shall be covered in the reports on comparative, published studies (and/or the confidential report as described more above and if such is prepared) are provided in the "Provisions" of this chapter and are not repeated here. 10.3.4 Reporting elements Overview As initial orientation (next to the exact list of reporting items and the separate LCA study report template) this chapter describes the content of the main reporting elements in an overview. After the practitioner has done the LCA study along the provisions and action points of the ILCD guidance document, he/she also needs to appropriately document this work. Such a detailed LCA report consist of at least four parts: the Main part, which is additionally condensed into a Technical Summary and an Executive Summary, and an Annex that documents e.g


Such a detailed LCA report consist of at least four parts: the Main part, which is additionally condensed into a Technical Summary and an Executive Summary, and an Annex that documents e.g. assumptions and used data (which can also be referenced). Confidential and proprietary information can be documented in a fifth element, a complementary Confidential report. Review reports are either annexed as well or referenced. The following text describes the general scope and purpose of the different report parts, details are given in the "Provisions" and the reporting template. This guidance document comes along with electronic templates for LCA reports (i.e. provide a chapter-structure and direct references to the reporting items), which should be used. For process data sets (i.e. parameterised and not parameterised unit processes, LCI results, partly terminated systems; and optionally including LCIA results), the ILCD reference format is provided as electronic LCI data set format


It should be used for LCI data sets provided together with LCA reports to ensure appropriate and complete documentation and IT compatibility for error-free electronic data exchange. 207 Note that the important ones are to be repeated and considered quantitatively in the sensitivity analysis and quantitatively and qualitatively in the interpretation. The relevant assumptions are also to be documented in the context where they belong, e.g. for processes together with the processes they concern at the relevant place (LCI chapter or scope definition)


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 10 Reporting First element: Executive Summary For non-technical audience. The summary shall be able to stand alone without compromising the results and conclusions / recommendations (if included) of the LCA. The target audience of the executive summary typically will be decision-makers, who may not have time or technical background for reading the detailed report. The executive summary shall as a minimum include key elements of goal and scope of the system studied. The main results from the inventory and impact assessment components shall be presented in a manner to ensure the proper use of the information, and relevant statements about data quality, assumptions and value judgments should be included. Finally, the executive summary report should state any recommendations made and conclusions drawn and shall give any limitations that may apply


Finally, the executive summary report should state any recommendations made and conclusions drawn and shall give any limitations that may apply. Second element: Technical Summary For technical audience / LCA practitioners. This summary should be able to stand alone without compromising the results of the LCA. The target audience of the report typically will be technical audiences, who may not have time for reading the full report or use it for getting an overview first. The technical summary should therefore also fulfil the same criteria about transparency, consistency, etc. as the detailed report. The technical summary shall as a minimum include the goal, the scope, with relevant limitations and assumptions, and an overall flow diagram of the system studied, and shall clearly indicate what has been achieved by the study