This is however only feasible if the legal limits apply to the specific process and country where it is operated and if compliance with these limit values is actually controlled and enforced. The default use of legal limits for the inventory is not appropriate, unless this is checked and justified for applicability in the analysed process and specific situation. Provisions: 7.4.2.8 Checking legal limits Limited applicability for future processes beyond some years from present. Note that these provisions are to be applied to each unit process separately, in case more than one is modelled (e.g. in the foreground system of an analysed system). I) MAY - Check legal limits: It is recommended to check for the existence of relevant legal limits as guidance on which flows to in any case include. One may use existing legal limits of e.g


I) MAY - Check legal limits: It is recommended to check for the existence of relevant legal limits as guidance on which flows to in any case include. One may use existing legal limits of e.g. Japan, the EU, the US in case of limited environmental legislation in the country where the process is operated and as far as the limits are technically transferable. If the legal limits apply in the country / market in which the represented

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


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results process is operated and are also enforced, they give an indication of the possible maximum values of the amounts of these flows. [ISO+] Note that legal limit values - also of the country where they originally apply - normally cannot be used as inventory values, unless this is checked and justified for the modelled process and in line with the goal. 7.4.2.9 From raw data to unit process inventory (Refers to aspects of ISO 14044:2006 chapter 4.3.3) The amount of products produced by a production unit process (or of functions performed in case of services) is required in order to relate the emissions and other flows to the functional unit and reference flow of this unit process


In data collection often accounts are available that report the total annual load of emissions and consumption of fuels, materials and ancillary chemicals of a process or a plant. These annual account figures must be quantitatively related to the amount of goods or services provided during the period which is covered by the account. Frequent errors: Un-reflected use of machine specifications A very common error, which is difficult to detect in review, is to model the performance of a process based on some theory on how it operates and not verifying this with data from the process in real operation. For electrical equipment, sometimes the specified maximum power consumption (e.g. “10 kW”) is used, implicitly assuming to be the average consumption. This does not consider that the equipment is not running all the time and that when it runs it typically is running not on maximum load. In other cases of collecting the raw data, only concentration measurements for emissions are available


In other cases of collecting the raw data, only concentration measurements for emissions are available. This applies e.g. to flue gas concentrations of priority air pollutants as required by legal authorities, to concentrations of specific pollutants in wastewater discharges, but also to product concentrations measurements in continuous processing operations. In order to be of use in the data compilation for the inventory, concentrations must be translated to mass flows, and this requires information about the volume of the e.g. flue gas, wastewater, product flow in which the concentration is measured. To relate the resulting numbers correctly to the reference flow, in a second step they must be scaled to the amount of product(s) of the process. Errors in this scaling including when converting additionally between units (e.g. from “ng/m3” to “kg”) can often be observed and must be carefully avoided


Errors in this scaling including when converting additionally between units (e.g. from “ng/m3” to “kg”) can often be observed and must be carefully avoided. This is best done by documenting all the calculation steps from the raw data to the final inventory data e.g. in one spreadsheet. This also eases interim quality control, review, and later updating of the data set. Frequent errors: Unit conversion errors Unit conversion errors resulting in values being in the range of 1,000 or more too large (e.g. when interpreting kg instead of g or mg) are easily detected. In the other direction, e.g. erroneously downscaling an e.g. PAH emission by a factor 1,000 or more is very difficult to detect as it does not peak out in the inventory analysis. Such cases need deeper expert inside to be observed as conspicuously low numbers. Even worst are errors of below one order of magnitude, as they can much easier pass unnoticed, while still rendering the data and conclusions invalid


Even worst are errors of below one order of magnitude, as they can much easier pass unnoticed, while still rendering the data and conclusions invalid. One potential source for such errors is the use of the “.” and the “,” for decimal separator that is handled differently in different regions and countries. Other unit conversion errors relate to using different unit systems (e.g. Imperial system to SI).


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results Per default the SI units shall be used for reporting, while - depending on data availability - other units will be necessarily used when collecting raw data. Provisions: 7.4.2.9 From raw data to unit process inventory Note that these provisions are to be applied to each unit process separately, in case more than one is modelled (e.g. in the foreground system of an analysed system). I) SHALL - Correct scaling to the functional unit(s) / reference flow(s): Correct scaling to the functional unit(s) / reference flow(s) shall be ensured when converting the raw data to inventory flows. Note that the e.g. measured concentrations, annual numbers, relative stoichiometric data, yield percentages, etc. usually need to be mathematically processed to correctly relate to the functional unit of the unit process


usually need to be mathematically processed to correctly relate to the functional unit of the unit process. II) MAY - Documentation of all steps: It is recommended to document all data treatment steps from the raw data to the inventory flows of the unit process, such as averaging/aggregation, scaling, unit-conversion etc. This substantially facilitates the review process in case questions come up and it eases later updating of the data set. Details see chapter 10 on reporting. [ISO+] 7.4.2.10 Solving confidentiality issues (Refers to aspect of ISO 14044:2006 chapter 5.2) Confidentiality issues may occur in data collection and they need to be respected in view of protecting technology know-how and patent rights. Such issues occur both for the foreground system data of the process operator and its tier-one suppliers, but may also occur in background data in cases where there are only 1 or 2 producers in a country or region


In all such cases special confidentiality agreements may be necessary for data collection and modelling, but also review. This may in extreme cases involve that the processes or system is modelled in-house and the external review is equally done in-site, i.e. without sending out the sensitive unit process information. For publication purposes the use of (independently and externally reviewed) LCI result data sets (e.g. aggregated from cradle to gate) can in most cases fully address or sufficiently reduce the confidentiality concerns, as such data does not allow to derive sensitive details about the operations. To ensure the necessary transparency for review, confidential information can be documented in a separate "confidential report" that is made accessible only to the critical reviewers under confidentiality; see in chapter 10.3.4. Similar confidentiality issues of protecting know-how and ownership exists for data developed e.g


Similar confidentiality issues of protecting know-how and ownership exists for data developed e.g. by consultants and research groups as secondary data providers. Equally here an independent external review can assure that the claimed data quality has actually been achieved and is correctly documented. Provisions: 7.4.2.10 Solving confidentiality issues I) MAY - Aggregation: Confidential and proprietary information can be protected by aggregation to LCI results data set and partly terminated system data sets. [ISO+] II) MAY - Confidential report: Transparency can be ensured by documenting confidential


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results information in a separate "confidential report" that is made accessible only to the critical reviewers under confidentiality; see chapter 10.3.4. 7.4.2.11 Interim quality control for improving data quality (Refers to aspects of ISO 14044:2006 chapters 4.3.3.2, 4.3.3.4 and in several other chapters) 7.4.2.11.1 General approach Quality control of the collected data on unit process as well as in the context of the system is an important part of data collection. The approaches that can be applied for this are the same as those foreseen for an external review and drawing on the procedures of chapter 9 on interpretation


The approaches that can be applied for this are the same as those foreseen for an external review and drawing on the procedures of chapter 9 on interpretation. While these step as are in principle the same as the ones taken at the end of each iterative round of doing the LCI / LCA study, they can be applied in a less extensive way and only drawing on their aspects. The interim quality control can hence include:  identifying significant issues,  completeness check,  sensitivity check, and  consistency check. This way, the data sets' accuracy, completeness and precision can be improved already in parallel to data collection. This can limit the number of full iterative rounds needed to achieve the required or aimed at quality of the final results. Drawing on these steps, the following can be checked in parallel to data collection and modelling:  Does the unit process inventory include all relevant product, waste and elementary flows that would be expected based on e.g


the input of processed materials, of the nature of transformations occurring in the process, and/or based on experience gained with similar processes? When doing so, make sure to reflect the required technological, geographical and time-related representativeness.  Are the amounts of the individual flows and of the chemical elements, energy and parts in the input and output in expected proportion to each other? There are often stoichiometric or other systematic relationships that can help to check whether measured data is plausible. Performing chemical element and energy balances, as well as cost balances between the input and the output of a unit process (and also LCI result) are key checks for improving data completeness, but also for identifying errors.  Controls may also be based on impact assessment results that are calculated ad hoc for the process as well as for the whole system


 Controls may also be based on impact assessment results that are calculated ad hoc for the process as well as for the whole system. They may reveal errors in the inventory results through showing unexpected high or low values of contributing elementary flows. It is also recommended to compare the LCIA results with data of the same or similar processes / systems from other sources to identify possible problems. However, this is only useful if the other sources are of high quality and especially high completeness. It must be avoided to assume completeness of a data set only because it includes all flows that are found in a similar process from another source.  On the system level, carefully check that methods have been applied consistently. This especially applies if combining data from different sources. Both for the steps from raw data to unit processes, but also and especially for combining LCI result data sets in a life cycle model.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results Critically check the findings and aim at clearly qualitatively and quantitatively explaining any observed discrepancies in the inventory data. This can be done by consulting additional data sources or technical experts for the analysed process. They may also help to improve the data, at least qualitatively.  It is recommended providing for each unit process data set an at least brief internal quality control report on the above findings. If the process is intended to support comparative assertions (e.g. as background data set) it shall be accompanied by a third-party report, as also required in ISO 14044.  Finally, reflect the findings in the reported data set quality criteria


as background data set) it shall be accompanied by a third-party report, as also required in ISO 14044.  Finally, reflect the findings in the reported data set quality criteria. Make sure that the data set documentation appropriately describes the process and the finally achieved accuracy, precision, and completeness as well as any limitations. 7.4.2.11.2 Obtaining better unit process data Identify and prioritise the need for obtaining better data Based on the above steps and for any still missing data or quantitative information, the following is recommended: To identify exactly which specific or higher quality data needs to be collected or obtained, for the initially missing data "reasonably worst case" flows and values would be used. These can be obtained via expert judgment. E.g


These can be obtained via expert judgment. E.g. an unknown "metal" emission could be "Lead" and/or "Arsenic" in case of a lead-zinc-ore roasting process, a missing "unspecific polymer part" could be an "injection moulded ABS or PUR" for a consumer electronic product. Note that this information and data is for the given case to be identified. Using these "reasonably worst case" approximations, LCI results and LCIA results are calculated for the compete system and a contribution analysis performed. Based on that, the most relevant flows and processes of this missing data/information are identified. If feasible and timely, this information can be used during data collection to better steer this step. Taking a system's perspective The procedure described above works directly on the level of the unit process and is straightforward for the flows' chemical elements‟ mass, energy, and cost and for other potentially relevant emissions. For the final completeness assessment criteria, i.e


For the final completeness assessment criteria, i.e. for quantifying the completeness of the data in terms of covered overall environmental impact, the environmental impacts related to the consumed goods and services of the unit process need to be included as well. This means that the unit process is first to be completed to a complete system over its life cycle. Using generic or average background data sets to complete this draft inventory, the completeness of the overall impact can be evaluated, and the collection of better unit process data can be focussed on the main contributing goods and services, i.e. their exact specification and amount. This check is again supported by quantifying the share of data of different quality levels among the aggregated LCIA results, i.e. which share is of "high quality", "basic quality" and which share only of "data estimate" quality, next to the share of lower quality data that is to be cut off (see more below)


which share is of "high quality", "basic quality" and which share only of "data estimate" quality, next to the share of lower quality data that is to be cut off (see more below). It is important to reiterate that completeness / cut-off criteria and precision / uncertainty calculations always relate to the final aggregation level of the developed data set: In the case the individual unit process data set is the deliverable of the LCI/LCA study, the procedure is as described above. However, any limited completeness in the background LCI data sets is not considered, as those were only added to complete the system and to identify the relevance of the product and waste flows of that unit process.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results Potential sources for data and information to fill gaps First step to deal with initially missing data is the attempt to measure/obtain the data at the process operator. If this fails, data can be obtained from a third-party LCI data provider. While data gaps are acceptable for purely methodological studies, a complete lack of funds or time cannot be an excuse for data gaps: If relevant data gaps remain at the end of the LCI/LCA study, it cannot deliver quality results and may fail to answer the initial question. However, budgets are always limited and data gaps will often occur also in appropriately funded LCI/LCA study


However, budgets are always limited and data gaps will often occur also in appropriately funded LCI/LCA study. At least the following principle options exist for dealing with missing information:  calculation from other, known information,  using information from similar processes or regions with similar process operation (and background processes in case of LCI results) or older data,  estimate the value based on specific expertise,  using methodologically not fully but sufficiently consistent data (what mainly refers to LCI data sets for background use), or  accept and document the gap. Which is the best solution, depends on the specific case: qualified estimates may be very accurate while using data from not sufficiently similar processes or regions may result in relevant errors. A good technical understanding of the process is indispensible to correctly deal with missing data. Measures taken are to be documented


A good technical understanding of the process is indispensible to correctly deal with missing data. Measures taken are to be documented. Calculating data values Often available information can be combined to generate the missing information, e.g. by stoichiometrically calculating CO2 emissions of an incineration process by multiplying the carbon content of the fuel with the stoichiometrical factor 44/12, assuming a full combustion140. Completing the inventory via correlations Another approach is to improve incomplete but measured foreground data (which often has only few emitted substances measured) via correlation with further elementary and waste flows as well as consumables, services etc. from generic data of the same process, thereby completing and improving the inventory. Adjusting data from other countries / markets or from similar technologies Another principle possibility is to adjust existing data that represent a similar situation


Adjusting data from other countries / markets or from similar technologies Another principle possibility is to adjust existing data that represent a similar situation. However, to do so requires a very good understanding of which differences exist e.g. in the technology mix between two countries, which specific raw material basis is used, which raw gas treatment technologies are applied, etc. (and also which legal emission limits may apply). The number of aspects is very extensive and specific for each case. As was already highlighted in a frequent error box in chapter 6.8.3, it can be found often in practice that data receive just a basic adjustment (e.g. by replacing electricity background data) and are assumed to sufficiently represent another country. Without working together with technical experts of the respective sector and / or country, and without a systematic and case-wise adjusted approach such an adjustment can be expected to not result in sufficient data quality. 140 I.e


140 I.e. 44 g per mol of CO2 divided by 12 g per mol of C.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results Expert estimates For still missing data, a value may be estimated based on expert judgment e.g. using data from a sufficiently similar process or the same process modelled for another country (given the technology, operation conditions, and e.g. abatement technologies are comparable). If a sensitivity analysis based on such estimates shows that the process may be important, the estimated data may have to be replaced by data that are more precise in order to meet the requirements on the precision of the overall results. Also here the expert should primarily have the necessary technical expertise. The also required LCA expertise can come from the LCA expert that performs the data modelling. An example: If e.g


Also here the expert should primarily have the necessary technical expertise. The also required LCA expertise can come from the LCA expert that performs the data modelling. An example: If e.g. particle emissions are only available as “Particles” without particle size information, a worst case assumption would be “PM < 0.2 μm”, a reasonable case assumption would look at the typical particle size class of a similar process and use that one (e.g. “PM 2 to 10 μm”). If no information on particle emissions is available at all, but expert judgement reveals that the process is known to emit relevant amounts (e.g. as it is an ore roasting or incineration process), it is inserted as PM flow and the appropriate particle size would be determined by looking into processes that generate particles in a comparable way


Using methodologically not fully consistent data As a last resort and upon individual justification methodologically not fully but sufficiently consistent data can be used to fill remaining data gaps. Data of methodologically different nature and entirely different modelling approaches cannot be used to fill data gaps, as no information can be given on the achieved accuracy, completeness, and precision and as the degree of methodological consistency equally cannot be stated. Only including data that improve the overall quality In order to actually improve the overall data quality, only data or data sets that effectively increase the overall quality of the final inventory of the analysed system shall be used to fill data gaps. That means that the individual data or data set's quality (i.e


That means that the individual data or data set's quality (i.e. combined accuracy, precision, completeness and its methodological appropriateness and consistency) has to be at least equivalent to the "Data estimate" quality level (see annex on data quality indicators and levels). It is argued to be better to report a gap (while documenting which specific information is available, e.g. the type of flow) instead of using e.g. background LCI data sets to fill the gap while at the same time reducing the overall data quality. The available information should however be kept, while without including them in the final inventory, quantitative impact assessment, etc. The next chapter has more on how to deal with such remaining gaps. On worst-case assumptions Note that reasonable worst-case or conservative assumptions are problematic if the data is foreseen to be used for comparisons: While a rather conservative (i.e


On worst-case assumptions Note that reasonable worst-case or conservative assumptions are problematic if the data is foreseen to be used for comparisons: While a rather conservative (i.e. higher) value may be seen as appropriate when providing inventory data of own products, this affects also subsequent uses on other systems and may result in distortions of the results of other systems and related comparisons. Conservative or reasonable worst-case assumptions are however useful as initial estimate for identifying whether a flow or process is to be inventoried at all. Conservative assumptions can also be used to evaluate he robustness of comparisons, i.e. to evaluate whether the


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results superiority of an alternative is still valid if conservative or even worst-case assumptions are made for its inventory values. Any form of conservative or worst-case estimates or processes must however not stay in the final process or system model. 7.4.2.11.3 Dealing with remaining unit process data gaps / missing data Overview After the above steps, some data may still be missing, qualitatively or quantitatively. This chapter deals with the question how to deal with these gaps in reporting. Types of missing data and information Missing information can be of different type and have different characteristics, and they require different ways to deal with them. There can be missing:  qualitative information (e.g


There can be missing:  qualitative information (e.g. specific kind of emission or consumable, such as "metals" emission to air, or "energy" consumed)  quantitative information (e.g. sufficiently precise amount of a flow, such as "below 0.005 kg", or "between 0.1 and 2.5 kg", "unknown amount") This can relate to  product or waste flows (what implies that the life cycle inventory of the provision of the product or treatment of the waste is equally qualitatively or quantitatively not sufficiently known)  elementary flows (what implies that often the classification, i.e


link to the relevant impact category/ies is/are missing, and in any case the specific characterisation factor(s) cannot be given) An additional difficulty is that the limited available information could be documented in the inventory of an unit process level, while when calculating LCI results, an appropriate solution is to be found how to combine such partial data gaps (qualitative or quantitative) with available information (e.g. how to sum up an unclear or unknown amount of lead emission to air with the same emission of another process that is known to be e.g. 0.00026 kg. Unknown kg plus 0.00026 kg = ?)


how to sum up an unclear or unknown amount of lead emission to air with the same emission of another process that is known to be e.g. 0.00026 kg. Unknown kg plus 0.00026 kg = ?). Principles to be followed The principles that are followed here to derive a suitable approach are  to keep the available information for further uses, including for interpretation of the relevance of gaps and for review  to support an automated use of the available information, while acknowledging that a use shall also be possible if uncertainty calculation is not performed and without increasing the complexity of the inventory with many specific flows and semiquantitative information  to avoid combining highly uncertain information / data with more certain data, i.e


to report a gap instead of decreasing the overall quality of the inventory item How to deal with remaining missing inventory data / information The following provisions are made:  Missing qualitative information for a unit process inventory item: The respective flow should be created and used in the regular inventory only if it is a product or waste flow.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results Unclear elementary flows (e.g. "Metals to air") shall not be kept in the regular inventory but this information shall be documented in another way. This can be either as clearly marked flows that shall not be combined with the elementary flows of the regular inventory when aggregating the data sets of the analysed system, The flows can be marked e.g. as "missing important" or "missing unimportant", as applicable (see more below), and be excluded from the aggregation. Or they can be documented exclusively in the descriptive information of the data set (e.g. as attached lists).  Missing quantitative information for a unit process inventory item: The flow should be inventoried


as attached lists).  Missing quantitative information for a unit process inventory item: The flow should be inventoried. If no quantitative information can be given, this has to be documented by marking the flow as “missing important” to avoid misleading readers, as the true value is not zero. The omission must be explicitly addressed and considered in the interpretation of the results. If a conservative estimate for a missing data fails to show any quantitative importance, a zero value141 may be entered for this data, but marking it as “missing unimportant”. If a mean value or a wide range of values (Min and Max) can be given, this should be entered in the inventory. Uncertainty information such as standard deviation and distribution type should be given if possible and if this information has sufficient precision. For both the above cases, the values shall not be aggregated when calculating LCI results. This can be achieved e.g


For both the above cases, the values shall not be aggregated when calculating LCI results. This can be achieved e.g. by marking theses inventory items as "missing important" or "missing unimportant", as applicable (see more below), and excluding such flows from the aggregation.  Missing qualitative and quantitative information: See preceding two points that are to be combined.  Missing LCI data for processes / systems in the background system: When aggregating the unit processes of the analysed system to LCI results, product and waste flows for which background data of sufficient quality is not available, these flows shall remain in the aggregated inventory, i.e. making the data set a "partly terminated system". The user of such data shall be explicitly informed in a prominent place that these parts of the system need to be still completed or the gap be considered in the further use and interpretation


The user of such data shall be explicitly informed in a prominent place that these parts of the system need to be still completed or the gap be considered in the further use and interpretation. The above referenced classification "Missing important" and "Missing unimportant" relates to the question whether the flow is relevant for the LCI results of the unit process data set in which it occurs, if completed to a system data set. Note that this shall include both the type of flow and its amount; for product and waste flows this includes the respective life cycle inventories of the system that they represent (for product flows) or of their management and treatment (for waste flows). The approximation of the flow's relevance may be supported by uncertainty calculation and quantitative calculation of data accuracy


The approximation of the flow's relevance may be supported by uncertainty calculation and quantitative calculation of data accuracy. 7.4.2.11.4 Documentation It is recommended to document all such combinations, extrapolations, calculations, correlations, expert judgements, approximations and measures to fill data gaps, etc. on individual data values on unit process level to support a review of the data. This can be done directly inside the unit process data set or in accompanying raw data documentation files. 141 LCA software generally does not have empty values or support inventory values such as ”<0.5” and the like. Also, such unspecified values cannot be summed up with existing values from other processes when calculating the LCI results. For these reasons the value ”0” is to be entered in the inventory. If information of the named type ”<0.5” is available, such should be documented as comment for the respective inventory flow or the raw data background documentation.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results Provisions: 7.4.2.11 Interim quality control These provisions can be applied for the entire system or the single unit process that is analysed / developed. Many of the following provisions on interim quality control are only recommendations, but the same controls may be part of a subsequent mandatory external review. General approach (7.4.2.11.1) I) SHALL - Validity check: A validity check of the collected data shall be performed during the process of data collection and unit process development, to confirm that the data is in line with the goal and scope requirements


The following provisions provides related operational recommendations on this requirement: II) MAY - Interim quality control as review along "interpretation" provisions: For the interim quality control on the unit process level, it is recommended to apply the data quality related technical aspects of the critical review (chapter 11) regarding the scope and methods of review together with the guidance of chapter 9 on interpretation (especially significant issues, sensitivity check, completeness check, and consistency check). These steps can however be done in a less formal way. Among others, the following may be done at this point: [ISO+] II.a) All relevant flows?: Does the unit process inventory include all relevant product, waste and elementary flows that would be expected based on e.g


the input of processed materials, of the nature of transformations occurring in the process, and/or based on experience gained with similar processes? Reflect the required technological, geographical and time-related representativeness. II.b) Flow amounts are proportionate?: Are the amounts of the individual flows and of the chemical elements, energy and parts in the input and output in expected proportion to each other? II.c) Support control by impact assessment: Controls may also be based on impact assessment results for the process as well as for the whole system. They may reveal errors in the inventory results through showing unexpected high or low values of contributing elementary flows. Compare the LCIA results with data of the same or similar processes / systems from other sources to identify possible problems. Make sure the other sources are of high quality and especially high completeness


Make sure the other sources are of high quality and especially high completeness. II.d) Method consistency?: On the system level, carefully check that methods have been applied consistently. This especially applies if combining data from different sources. II.e) Follow up on discrepancies: Check and explain or correct any observed discrepancies in the inventory data by consulting additional data sources or technical experts for the analysed process. II.f) Report on findings: It is recommended providing for the unit process data set an at least brief internal quality control report on the above findings. II.g) Reflect findings in data set quality indicators: Make sure that the data set documentation appropriately describes the process and the identified accuracy, precision, and completeness as well as any limitations.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results Provisions: 7.4.2.11 Interim quality control Obtaining better unit process data (7.4.2.11.2) III) SHALL - Dealing with initially missing data: The potential importance of initially missing data shall be checked in the following way and relevant gaps shall be filled if possible and as detailed below: [ISO!] III.a) SHOULD - Identify relevance of initially missing data: A reasonable worst case or at least conservative value for the missing data should be used in a first screening to see if they may influence the overall results of the LCI/LCA study. This reasonable worst case or conservative value may be derived by inference from knowledge of similar or related processes or from correlation or calculation from other flows of the process


This reasonable worst case or conservative value may be derived by inference from knowledge of similar or related processes or from correlation or calculation from other flows of the process. This includes identifying and inventorying flows that were initially not known to occur in the analysed process but that could not be excluded entirely. III.b) SHOULD - Dealing with relevant, initially missing data: If this screening shows that the missing data may be of importance, in further iterations of the LCA work it should be attempted to first identify whether the flow is actually occurring in the analysed process and if so to get the yet missing data. As second option sufficiently good estimates should be obtained. As third option, if also that is not possible, the gap should be kept and reported


As second option sufficiently good estimates should be obtained. As third option, if also that is not possible, the gap should be kept and reported. (Details see separate provisions more below): III.c) SHALL - Filling data gaps with estimates of defined and minimum quality: III.c.i) SHALL - For each newly modelled unit process any initially missing data should be documented in a transparent and consistent way. At the end of the iterative steps of improving the data set, the finally missing data and the potential use of data estimates to fill data gaps shall be documented in a transparent and consistent way (see chapter 10 on reporting). III.c.ii) MAY - For judging the relevance of an initial data gap, it is necessary to approximate the achieved accuracy, completeness and precision of the overall environmental impact on system level


III.c.ii) MAY - For judging the relevance of an initial data gap, it is necessary to approximate the achieved accuracy, completeness and precision of the overall environmental impact on system level. This necessarily needs that the subsequent steps of modelling the life cycle and calculating LCI results and LCIA results need to be done first (see next chapters). It is recommended to do this in parallel to developing the unit process data set. For unit processes this means completing the life cycle model around the unit process with background data. Any limited completeness in the used background data shall be not considered when calculating the achieved degree of completeness for the unit process for the final reporting. III.c.iii) MAY - For filling data gaps for single flows estimate data (sets) may be considered to be used


III.c.iii) MAY - For filling data gaps for single flows estimate data (sets) may be considered to be used. Such may be e.g.: III.c.iii.1) generic or average data for missing specific data, III.c.iii.2) average data of a group of similar products for missing inventory data for other, not yet analysed products of that group, III.c.iii.3) correlation with other, more complete and high quality data for


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results Provisions: 7.4.2.11 Interim quality control the same or similar process but from other data sources (e.g. industry average data for improving a producer-specific process), III.c.iii.4) justified judgements of technical experts / process operators. III.c.iv) SHALL - Data gaps shall generally be filled methodologically consistent data. Gaps of low relevance may also be filed with methodologically not fully but sufficiently consistent data sets while being developed along the guidance of this document and meeting the overall quality requirements as detailed below. III.c.v) SHALL - Only data that increase the overall quality of the final inventory of the analysed system shall be used to fill data gaps. That means that the individual data / data set's overall quality (i.e


That means that the individual data / data set's overall quality (i.e. combined accuracy, precision, completeness, and methodological appropriateness and consistency) shall be equivalent to at least the "Data estimate" quality level; see annex 12.3. Note that this shall include both the quality of the used data estimate and of the amount of the flow. That semi-quantitative approximation of the integrated data estimate plus flow amount quality shall be based at least on an individually, briefly justified expert judgement, explicitly considering the named shortcomings; this may be supported by uncertainty calculation and quantitative calculation of data accuracy. Note that both the approach(es) used to estimate initially missing data and the resulting lack of representativeness, precision and methodological consistency on data set level is later to be clearly documented and explicitly considered when declaring the achieved data set quality


Dealing with remaining unit process data gaps / missing data (7.4.2.11.3) IV) SHALL - Document remaining data gaps: If data estimates cannot be made available that would meet the above requirements, the data gap shall be kept and be documented instead. The following provisions are made: [ISO!] IV.a) Missing qualitative information for a unit process inventory item: The respective flow should be created and used in the regular inventory only if it is a product or waste flow. Little specified elementary flows (e.g. "Metals to air") shall not be kept in the regular inventory but this information shall be documented in another way. This can be either as clearly marked flows that shall not be combined with the elementary flows of the regular inventory when aggregating the data sets of the analysed system, The flows can be marked e.g. as "missing important" or "missing unimportant", as applicable (see more below), and be excluded from the aggregation


as "missing important" or "missing unimportant", as applicable (see more below), and be excluded from the aggregation. Or they can be documented exclusively in the descriptive information of the data set (e.g. as attached lists). IV.b) Missing quantitative information for a unit process inventory item: The flow should be inventoried. If no quantitative information can be given, this has to be documented by marking the flow as “missing important” to avoid misleading readers, as the true value is not zero. The omission must be explicitly addressed and considered in the interpretation of the results. If a conservative estimate for a missing data fails to show any quantitative importance, a zero value may be entered for this data, but marking it as “missing unimportant”. If a mean value or a


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results Provisions: 7.4.2.11 Interim quality control wide range of values (Min and Max) can be given, this should be entered in the inventory. Uncertainty information such as standard deviation and distribution type should be given if possible and if this information has sufficient precision. For both the above cases, the values shall not be aggregated when calculating LCI results. This can be achieved e.g. by marking theses inventory items as "missing important" or "missing unimportant", as applicable (see more below), and excluding such flows from the aggregation142. Or they can be documented exclusively in the descriptive information of the data set (e.g. as attached lists). IV.c) Missing qualitative and quantitative information: See preceding two points that are to be combined


as attached lists). IV.c) Missing qualitative and quantitative information: See preceding two points that are to be combined. IV.d) Missing LCI data for processes / systems in the background system: When aggregating the unit processes of the analysed system to LCI results, product and waste flows for which background data of sufficient quality is not available, these flows shall remain in the aggregated inventory, i.e. making the data set a "partly terminated system". The user of such data shall be explicitly informed in a prominent place that these parts of the system need to be still completed or the gap be considered in the further use and interpretation. Note that any kind of worst case or conservative data and assumptions shall not be kept in the inventory of LCI data that are foreseen to be applicable for comparisons, unless the representing process operators or system producers themselves wish so (e.g. to align LCI data reporting with other values reported on e.g


to align LCI data reporting with other values reported on e.g. site or company level). Note that reasonably worst-case data may however be used for scenarios and for checking the robustness of comparisons when doing the sensitivity analysis. Note the specific requirements for product comparisons such as on e.g. the consistency of methods, data quality, and assumptions across the compared alternatives (for details see chapter 6.10). 7.4.3 Overarching method provisions for specific elementary flow types (Refers to aspects of ISO 14044:2006 chapters 4.2.3.5 and 4.3.2.2) 7.4.3.1 Introduction and overview (Refers to aspects of ISO 14044:2006 chapters 4.2.3.5 and 4.3.2.2) A couple of issues are of overarching relevance and require the same, compatible solutions in support of integration of data compiled along supply-chains and by different developers. They also serve to improve reporting and easing review of the LCI/LCA study


They also serve to improve reporting and easing review of the LCI/LCA study. They equally are of interest for defining the reference elementary flows of the ILCD system and Data Network, together with the provisions on “Nomenclature and other conventions” that are given in the respective separate guidance. At the same time they provide guidance for further, consistent elementary flows to be created expanding that initial list. 142 LCA software generally does not have empty values or text entries for the amount of an inventory flow, as it must be able to sum up the entries. If hence a value zero is (automatically) assigned, the classification "missing important" ensures that this gap is clearly documented and that flow can be treated differently.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results Furthermore, some issues are strongly interlinked with LCIA method development and characterisation factor provision (e.g. sum indicators and elementary flow groups, see next subchapter). Other overarching provisions relate to product and waste flows. These were already mentioned earlier such as the inventorying of their energy content and chemical element composition in support of interim quality control, review and improving data quality. Others relate to specific process types and are addressed in the sub-sequent chapter. A number of considerations are being made to derive the most appropriate solutions to these overarching methodological issues, especially for elementary flows:  Distorted impact assessment and “hidden” highly impacting flows in aggregated inventory values must be avoided


 Incomplete impact assessment due to “forgotten” newly created flows is to be avoided.  The number of flows in the inventory should be kept as low as reasonably possible without relevantly affecting impact assessment, i.e. the differentiation of flow data sets should be not more fine than supported by state-of-the-art LCIA methods and not coarser than required to capture differences in the LCIA results.  The normal LCA practitioner cannot generally be expected to calculate and assign specific or composed impact factors.  Limitations in data availability (or the possibility to derive data via calculations, or sum indicator break-down lists derived from similar processes, etc.) and in budgets are to be accommodated as far as possible, without affecting the quality or robustness of the analysis.  A broad compatibility of elementary flows, independently of applied LCI modelling frameworks is to be achieved


 A broad compatibility of elementary flows, independently of applied LCI modelling frameworks is to be achieved. Common for both attributional and consequential modelling are a couple of overarching methodological issues that relate to inventory flows and inventory modelling. Among these are question on inventorying sum indicators and resource flows, how to inventory future longterm emissions, how to model CO2 uptake, storage and release, and the like. These are to be dealt with in the same way, to ensure that LCI data from different data developers can usefully be combined with each other when modelling systems. Equally these serve to ensure that LCIA factors are readily available and elementary flows are not “forgotten”, as a LCIA factor does not exists and practitioners cannot regularly derive specific factors


7.4.3.2 Emission of measurement indicators and elementary flow groups (Refers to aspects of ISO 14044:2006 chapter 4.2.3.5) Introduction and overview Elementary flows should wherever possible be inventoried as individual substances / interventions rather than as measured indicators such as “AOX” (Adsorbable organic halogenated compounds) or “COD” (Chemical Oxygen Demand) emissions or elementary flow groups like “heavy metals” or “hydrocarbons” emissions. Such measured and grouped elementary flows are in general are not suitable for a subsequent impact assessment and can cause large bias in the results, either exaggerating or underestimating the real impact potential.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results Practical approach Measurement indicators (i.e. measured emission characteristic such as “VOC” (Volatile Organic Compounds) and “COD”) and to a lower degree also certain flow groups (i.e. groups of elementary flows such as “Alcohols”) are common in industry practice of measuring emission data e.g. due to legal compliance requirements, measurement techniques (e.g. flame ionization detectors) or in order to limit highly costly measurements of many single substances. Directly measured data on the level of single substance elementary flows are hence often not available. This is (and will stay) the LCI reality the LCA practitioner has to face


Directly measured data on the level of single substance elementary flows are hence often not available. This is (and will stay) the LCI reality the LCA practitioner has to face. It is hence acknowledged that measurements of individual species are often not possible or affordable, but technology experts with knowledge about a specific process or process type (e.g. “solid fuel incineration”) may be able to quantitatively differentiate the emissions on a more detailed level. Such process-type-specific “emission fingerprints” (e.g. for heavy metals composition of the off-gas from a steel blast furnace refinery or the VOC composition from diesel motor off-gases) can be taken case-by-case from industry or research studies. Default break-down lists of the most commonly measured indicators for a range of relevant technology processes could be developed in subsequent work under the ILCD System


Default break-down lists of the most commonly measured indicators for a range of relevant technology processes could be developed in subsequent work under the ILCD System. For some processes with very heterogenic emission profiles and for some sum indicators and flow groups a simple splitting up into its components is not directly possible but needs a further differentiation, by also considering the process‟ operation condition, i.e. having more than one profile for such processes. However, a number of LCIA-wise rather homogeneous sum indicators and flow groups can be used, until default break down lists are generally available (the “Provisions” give the detailed provisions). The situation is more complicated, if some of the constituents are measured separately and the remainder amount is inventoried (e.g. the amount of Carbon monoxide emissions would be known and its mass subtracted from the amount of “Diesel engine off-gas” in the inventory)


the amount of Carbon monoxide emissions would be known and its mass subtracted from the amount of “Diesel engine off-gas” in the inventory). This distorts the composition of the sum parameter and typically renders the LCIA impact factor distorted for the remaining amount of the “Diesel engine off-gas” (i.e. without the CO). A partial split of measured indicators should be avoided, as the remainder will typically lead to a distorted impact assessment. At the same time is it not permissible to hide highly impacting (e.g. toxic) substances in common sum indicators (e.g. may PAHs (Polycyclic aromatic hydrocarbons) not be hidden in COD, etc.). These particularly impacting substances should be singled out, if they were measured separately or their existence and amount can be derived in other ways. Partial splitting with singling out flows with a lower than average impact shall not be done in any case


Partial splitting with singling out flows with a lower than average impact shall not be done in any case. As one exception for sub-stance groups, for Dioxins it is very wide praxis to inventory them as 2,3,7,8-TCDD equivalents (2,3,7,8-Tetrachlorodibenzodioxin human toxicity equivalents). This is argued to be acceptable as the equivalent number already relates to the relevant impact of interest, i.e. eco-toxicity and human toxicity. However, if available individually, the single species shall be inventoried. The resulting detailed lists of permitted measurement indicators and substance flow groups is given in the "Provisions". Provisions: 7.4.3.3 Emission of measurement indicators and elementary flow groups I) SHALL - Measurement indicator and substance group elementary flows: These shall be inventoried as follows: [ISO!]


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results I.a) Avoid indicators and flow groups; with permissible exceptions: Measurement indicator and substance group elementary flows shall be avoided in the inventory by splitting them up to single substances. Exclusively the following exceptions are permissible, while they should be split as well: COD143, BOD, AOX, VOC, NMVOC, PAHs, PCBs, TOC, DOC, Nitrogen in Nitrogen compounds (excluding N2, N20), Phosphorus in Phosphorus compounds, Dioxins (measured as 2,3,7,8-TCDD human toxicity equivalents). I.b) Restrictions on partial splitting: A partial splitting up of measurement indicators and substance group flows should be avoided. This is except for singling out exclusively elementary flows that have higher impacts than the average of the indicator / group and that should be singled out


This is except for singling out exclusively elementary flows that have higher impacts than the average of the indicator / group and that should be singled out. Partial splits with singling out elementary flows with less than average impacts shall not be done. If singling out single substance elementary flows from the above indicators / flow groups, only the remainder amount of the indicator or flow group shall be inventoried. I.c) No double-counting: Double-counting across the above indicators / flow groups and with the contained individual substances shall be avoided (i.e. correct is to inventory either "BOD" or "COD"; either "VOC" or "NMVOC" plus "Methane"; either "Nitrate" plus "Ammonia" plus ... or "Nitrogen in Nitrogen compounds"; etc.). I.d) Document composition: If measured composition information of a split measurement indicator or substance flow group is not available, an assumed composition can be used. Approach and assumptions shall be documented


Approach and assumptions shall be documented. Note that the composition of a measurement indicator or substance flow group can often be derived without direct measurement from process know-how (e.g. processed materials, educts, etc.) or those of sufficiently similar process can be considered144. I.e) Do not combine measured flows: Individually measured substances shall not be integrated/combined into measurement indicators and elementary flow groups but be inventoried individually. II) MAY - Use "Reminder flow" to keep originally measured indicator or flow group: It is recommended to document the originally measured amount of the split indicator or flow group in the inventory as a “Reminder flow”. "Reminder flows" shall later be excluded from the impact assessment, i.e. have no characterisation factors and be clearly identified as "Reminder flows" (on naming see chapter 7.4.3.8)


"Reminder flows" shall later be excluded from the impact assessment, i.e. have no characterisation factors and be clearly identified as "Reminder flows" (on naming see chapter 7.4.3.8). [ISO+] Note that if the above provisions cannot be fully met, this shall be explicitly considered when reporting achieved data quality and when interpreting the results of LCA studies. Note that LCI data sets' inventories that do not meet the above requirements are not compliant with the ILCD nomenclature. 143 COD = Chemical oxygen demand, BOD = Biological oxygen demand, AOX = Adsorbable organic halogenated compounds, VOC = Volatile organic compounds, NMVOC = Non-methane volatile organic compounds, PAH = Polycyclic aromatic hydrocarbons, PCB = Polychlorinated biphenyls, TOC = Total organic carbon, DOC = Dissolved organic carbon. 144 Default-composition tables for different process-types and industries might be developed in PCR-type or sector-specific guidance documents.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results 7.4.3.3 Emission of ionic compounds (Refers to aspects of ISO 14044:2006 chapter 4.2.3.5) Introduction and overview For a number of compounds methodological questions arise how to inventory them, e.g. is the ionic but environmentally very stable substance CdS to be inventoried as the two ions Cd2+ and S2- or as the compound CdS? For the impact assessment this is crucial, as the fate strongly depends on water solubility. For particle emissions only those that do not dissolve in the lungs act carcinogenic. To limit the number of elementary flows and to avoid "forgetting" flows that have no impact factors assigned, it is desirable to limit the number of single elementary flows by inventorying the ions separately


Along the initially named considerations, the following solution is derived: Easily water soluble ionic compounds (e.g. salts such as Ammonium nitrate, Cadmium chloride, etc.) are to be inventoried as the ions of which they exist: These compounds, when released to the environment (with some exceptions however) behave largely as if dealing with the ions separately. Looking at a single particle and its solubility in one droplet of water of 1mm diameter and hence about 0.0005 ml (formed as rain or in the lung tissue), the limit is set roughly where at 20oC less than half of a particle of 2 μm diameter dissolves in that amount of water. This depends also on the density of the material, but for orientation assuming the density to be 2 kg/litre resulting in a particle mass of about 8*10E-12 g, the border is at 0.5*8*10E-12 g / 0.0005 ml = 8*10E-9 g/ml (or 8*10-6 g/litre, i.e. about 10 μg/litre)


about 10 μg/litre). As convention the limit is hence set at a solubility in water at 20oC of below 10 μg/litre145,146. Less good water soluble compounds are to be inventoried as compound. Note that this provision - other than the similar provision on particles does not apply for water-soluble, dissociating organic compounds. Provisions: 7.4.3.3 Emission of ionic compounds I) SHALL - Inventory easily water soluble salts as ions: For data sets as deliverables, emissions to air, water, or soil of easily water-soluble ionic compounds (salts) shall be inventoried as separate ions, unless the selected LCIA methods would require otherwise. As convention, the limit is set at a solubility in water at 20oC of 10 μg/litre, above which the ions shall be inventoried separately, below which the compound shall be inventoried. This applies unless the selected LCIA method requires otherwise


This applies unless the selected LCIA method requires otherwise. [ISO!] Note that if the above provisions cannot be fully met, this shall be explicitly considered when reporting achieved data quality and when interpreting the results of LCA studies. Note that LCI data sets' inventories that do not meet the above requirements are not compliant with the ILCD nomenclature. 7.4.3.4 Emission of particles to air (Refers to aspects of ISO 14044:2006 chapter 4.2.3.5) Overview Three issues play a role for particulate mater: 145 Some examples: CaCO3 = 600 μg/l, Cu(OH)2 = 17 μg/l, CdS = 0.0001 μg/l. 146 For orientation: for a substance of 100g/mol this is hence 0.001 mol/litre.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results Particle size classes, water solubility, and additivity of impacts. Particle size classes Firstly, and given the different impact, particulate matter should be split up into different size classes with different toxicity implications (as the size determines the access to the lungs and uptake into the lung tissue). Water solubility Secondly for particulates it is to be considered that only particulate matter emissions to air that are insoluble in water are relevant for human toxicity. The easily water-soluble ones such as e.g. Ammonium nitrate when inhaled will immediately solve in the tissue water and pose no carcinogenic effect due to their particle character


The easily water-soluble ones such as e.g. Ammonium nitrate when inhaled will immediately solve in the tissue water and pose no carcinogenic effect due to their particle character. Hence, not to overestimate the impact, the composition of the measured PM should be identified or derived from the sourceprocess to determine whether/how much of it is water-soluble. Note that this applies not only to inorganic salts but also to e.g. organic substances. The third issue also relates to other types of emissions: Emission of substances with several additive / serial action schemes Elementary flows with additive / serial action schemes (e.g. NOx as contributing to both Photochemical ozone creation (summer smog) and Eutrophication) need to carry more than one characterisation factor. Complex elementary flows may need a special treatment in inventorying. E.g


Complex elementary flows may need a special treatment in inventorying. E.g. an emission to air of 0.0001 kg Particles (<2.5 μm) that contains 50 % Chromium VI implies an additive cancer potential from both being a particle and being (to 50 %) Chromium VI. To avoid that a huge number of “Particle XY” elementary flows with different composition needs to be inventoried (including the problem for LCA practitioners to correctly assigning the impact factors), a splitting up into the single components (e.g. in the given example into 0.0001 kg “Particles <2.5 μm” plus 0.00005 kg “Chromium VI”) is recommended. In this case (and analogously if both the amount of particles and the amount of chromium are separately measured but in the same off-gas stream), both amounts are inventoried as separate elementary flows. Note that this results in a (in absolute terms however very small) double counting of the mass. The impact effect however is more appropriately addressed


Note that this results in a (in absolute terms however very small) double counting of the mass. The impact effect however is more appropriately addressed. As an exact mass-balance of LCI results is never given in practice (as e.g. incineration air is left out, certain water losses are not inventoried etc.) this minor double counting of the masses (while correctly addressing the effect of the inventory) is acceptable147. Note: In the cases of interest in a more detailed impact modelling and taking into account more details such as speciation, in such specific application cases also more specific elementary flows can be created, of course, while for background databases this should be avoided, as to ensure a consistent databases and to have appropriate LCIA factors available and fully linked to the inventory. 147 Discussion of other options: Other solutions could be, to inventory only the most important aspect as a flow (in the above example e.g


147 Discussion of other options: Other solutions could be, to inventory only the most important aspect as a flow (in the above example e.g. as particles <2.5 μm without Chromium) or to enter only the most important impact factor into the combined flow. This however creates problems, where the substance contributes to different impact categories (e.g. "NO2 to air" to Human Toxicity and Eutrophication), since it is not possible to determine independently, which of the different impacts is quantitatively more important. The possibility to apply reduced characterisation factors for both effects - which may be developed in the future by LCIA – is kept. This is however not expected to solve this issue, as it causes a number of other problems in LCI practice. Among others a steadily growing set of elementary flows of slightly different composition that would require the final users / LCA practitioners to correctly calculate and assign the impact factors to these new flows.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results Provisions: 7.4.3.4 Emission of particles to air I) SHALL - Inventory only poorly water soluble compounds as particles: Particulate matter (PM) emissions to air shall include only poorly water-soluble compounds below a solubility in water at 20oC of 10 ug/litre, as far as feasible. Expert judgement may be needed to identify the composition of the particles. [ISO!] II) SHOULD - Differentiate particle size classes: Particles should be reported split up by particle size class <0.2 μm, 0.2-2.5 μm, 2.5-10 μm, >10 μm if the information is available. <10 μm may be used alternatively is a more differentiated information below 10 μm is not available. This applies unless the selected LCIA method requires otherwise


<10 μm may be used alternatively is a more differentiated information below 10 μm is not available. This applies unless the selected LCIA method requires otherwise. [ISO!] III) SHALL - Inventory particles additionally as the substances they are composed of: Particles shall be inventoried as both PM and additionally as elementary flows of their environmentally relevant components (e.g. metals contributing to cancer effects), i.e. double counting their mass in the inventory, as far as possible. This applies analogously to other emissions with additive action schemes. [ISO!] Note that if the above provisions cannot be fully met, this shall be explicitly considered when reporting achieved data quality and when interpreting the results of LCA studies. Note that LCI data sets' inventories that do not meet the above requirements are not compliant with the ILCD nomenclature


Note that LCI data sets' inventories that do not meet the above requirements are not compliant with the ILCD nomenclature. 7.4.3.5 Emission of substances of complementary, alternative action schemes (Refers to aspects of ISO 14044:2006 chapter 4.2.3.5) For the emission of substances of complementary, alternative action schemes, the fate is fully modelled in the LCIA method and the impact factors consider this fact. An example are NOx emissions to air that either have a Human toxicity effect (inorganic respiratory effect) or an Eutrophication effect on land and water bodies)


An example are NOx emissions to air that either have a Human toxicity effect (inorganic respiratory effect) or an Eutrophication effect on land and water bodies). 7.4.3.6 Resource elementary flows (Refers to aspects of ISO 14044:2006 chapter 4.2.3.5) 7.4.3.6.1 Energy resources (Refers to aspects of ISO 14044:2006 chapter 4.2.3.5) Taking into account the initially made considerations, the following can be concluded for energetic resources: To evaluate the resource depletion of energetic resources, with currently used and practice-tested impact models do not require differentiating them by their specific energy-content/mass ratio or by the country or origin. This allows to keep the number of non-renewable energy resource elementary flows low, i.e. instead of hundreds of elementary flows of the type "Crude oil Norway", "Crude oil Saudi Arabia", or “Brent Spar”, “Tia Juana Light” etc., or "Crude oil 42.6 MJ/kg", "Crude oil 42.3 MJ/kg", etc


instead of hundreds of elementary flows of the type "Crude oil Norway", "Crude oil Saudi Arabia", or “Brent Spar”, “Tia Juana Light” etc., or "Crude oil 42.6 MJ/kg", "Crude oil 42.3 MJ/kg", etc. only 1 (most energy resources) to 3 (crude oils) elementary flows are required (see below). To support established practice in resource-depletion impact assessment of energetic resource elementary flows, exclusively a differentiation by type of deposit/source is required, i.e. primary, secondary, tertiary crude oil and open pit or underground mining of hard coal. Other fossil fuel resource elementary flows (natural gas, oil shale, tar sand, lignite, peat) do currently not need a differentiation.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results For renewable energy forms, the usable amount of energy that is extracted from nature is to be inventoried. E.g. for solar electricity and heat this relates to the amount of electricity and/or heat captured by the solar cells (i.e. not the total solar energy, but what is delivered directly by the cells as electricity and/or usable heat). For biomass from nature this is the amount physically embodied, measured as Lower calorific value, however of the water-free substance (i.e. measured as if the e.g. wood would be oven-dry). Note that biomass from fields and managed forests is no elementary flow. In that case, the named energy resources shall be inventoried directly as the respective elementary flows, e.g


Note that biomass from fields and managed forests is no elementary flow. In that case, the named energy resources shall be inventoried directly as the respective elementary flows, e.g. "Solar energy" as "Renewable energy resources from air", expressed as Lower calorific value and measured in the reference unit MJ. As to the reference flow property and the reference unit of energetic resources see the respective chapter in the separate document “Nomenclature and other conventions”. 7.4.3.6.2 Ores for winning metals or other elemental constituents (Refers to aspects of ISO 14044:2006 chapter 4.2.3.5) Taking into account the initially made considerations, the following can be concluded for non-energetic resources: To evaluate the resource depletion of most non-energetic resources with currently used and practice-tested LCIA methods, it is not required to differentiate them by their specific element-content/mass ratio or by the country or origin


This allows lowering the number of elementary flows in the inventory, following a similar approach as for the non-renewable energetic resource elementary flows (see also previous point). The inventorying of (metal) ore elementary flows shall hence be based on a differentiation of ore bodies or minerals into the single elements' elementary flows (e.g. 0.012 kg “Lead” and 0.023 kg “Zinc” elementary flows are inventoried, when e.g. 1 kg Lead-zinc ore (1.2 % Pb, 2.3 % Zn) is extracted. 0.78 kg "Anhydrite" is inventoried, when e.g. an anhydritecontaining body of 1 kg Anhydrite-containing rock (78 % anhydrite) is extracted.) This at the same time allows to overcome the problematic current situation of having a huge number of “impact-free”/forgotten specific ores and minerals in the inventory for which by-default no impact factors are provided. For functional/material resources it is however necessary to capture their specificity (e.g. “Granite”)


For functional/material resources it is however necessary to capture their specificity (e.g. “Granite”). To complete the mass flow of the resource, the non-resource part of the ore is to be inventoried as “inert rock” “Resources from ground” (or water, as applicable)148. 7.4.3.6.3 Land use (Refers to aspects of ISO 14044:2006 chapter 4.2.3.5) Direct land use and land transformation shall be inventoried along the needs of the applied LCIA method (if included in the impact assessment). Specific guidance is not provided at this point but might be given in a supplement or revised version. For CO2 release caused by land use and land transformation, the use of the most recent IPCC CO2 emission factors shall be used, unless more accurate, specific data is available. Detailed provisions and table with the current IPCC factors: see chapter 7.4.4.1 and annex 13. 148 In practice, the inventory of a lead-zinc ore mining process would have in the input-side the above named e.g


148 In practice, the inventory of a lead-zinc ore mining process would have in the input-side the above named e.g. “Lead”, “Zinc”, and “Inert rock” elementary flows, while in the output side the product flow (!) “Lead-zinc ore; 1.2% Pb, 2.3% Zn”. (After processing the “tailings” would be a waste that is modelled to the leached emissions.) This has the effect that when calculating LCI results, only the relevant elementary resource flows “Lead” and “Zinc” remain in the inventory, resulting in the desired reduction of the number of elementary flows in the inventory.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results Other emissions in result of land transformation (e.g. NO3 - losses to water, emissions from biomass burning, soil erosion etc.) should be measured or modelled for the given case or using authoritative sources. See chapter 7.4.4.1 also for related issues when modelling agricultural systems. Indirect land use is an issue under consequential modelling that applies to all kinds of land uses and is hence addressed in chapter 7.2.4.4. 7.4.3.6.4 Fossil and biological CO2 uptake and release of CO2 and CH4 (Refers to aspects of ISO 14044:2006 chapter 4.2.3.5) For better methodological clarity and flexibility as well as easier communication, the release of carbon dioxide (CO2) and Methane (CH4) is recommended to be additionally differentiated between fossil and biological sources


Land use change-related CO2 emissions from soil, peat etc. in all cases and from biomass and litter of virgin forests shall be inventoried as "Carbon dioxide (fossil)". Emissions from biomass and litter of secondary forests shall be inventoried as "Carbon dioxide (biogenic)". See also chapter 7.4.3.7.3 on uptake of CO2 by plants and release at the end-of-life ("carbon storage"). 7.4.3.6.5 Water use (Refers to aspects of ISO 14044:2006 chapter 4.2.3.5) Taking into account the indicator "water use" is still complex since water can come from various sources some of which are renewable (e.g. seawater), others not (e.g. fossil / deep groundwater). Also the release of used water to the environment can have very different forms and ways, some of which only distribute the water from one place to another (e.g. irrigation water), some changing its state (e.g. river water to steam for cooling), and some mainly its quality


irrigation water), some changing its state (e.g. river water to steam for cooling), and some mainly its quality. It is recommended to differentiate at least the following on the input side:  surface freshwater,  renewable groundwater,  fossil / deep groundwater,  sea water. On the output side it is recommended to at least differentiate:  Emission in liquid form (e.g. infiltration to soil from irrigation systems, emission of treated wastewater to rivers), and  emission in form of steam (e.g. cooling water loss as steam from e.g. cooling towers, loss from irrigation systems by evaporation and evapotranspiration). Emissions in form of steam are lost for other uses. They also change the hydrological and microclimatological situation, hence would require a specific impact assessment. No specific recommendation is made for water use in hydropower stations


They also change the hydrological and microclimatological situation, hence would require a specific impact assessment. No specific recommendation is made for water use in hydropower stations. The gained renewable energy shall be inventoried separately and the effect of land use, changed hydrology and ecosystem-connectivity in case of dam systems is addressed with other instruments. Changes in the quality of the used water shall be inventoried via separate elementary flows, i.e. as emissions of substances or of heat to water.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results Important is to clearly differentiate between internally recycled water (e.g. cooling water) and the actual net consumption of water in form of extracting it from the environment. Provisions: 7.4.3.6 Resource elementary flows I) SHALL - Provisions for inventorying resource elementary flows: Resource elementary flows shall be inventoried as follows, with exceptions only if necessary to meet the need of the applied LCIA method: [ISO!] I.a) Energy resources (7.4.3.6.1): I.a.i) Non-renewable: These shall be inventoried as type of energy resource and in few cases (only primary, secondary, tertiary crude oil and open pit or underground mining of hard coal) these should be differentiated exclusively by resource extraction type, if this information is available (e.g


“Crude oil, secondary extraction” but not “Crude, Tia Juana Light”; "Hard coal, underground" but not "Hard coal, Western Germany; 39.4 MJ/kg"). The energy/mass relationship shall be provided for all energy resource flows except for nuclear ores. The energy content shall be expressed in the Lower calorific value of the water-free resource, measured in the reference unit MJ. See also separate document "Nomenclature and other conventions". Note that peat, biomass of primary forests, and some other biogenic energy resources are "non-renewable". I.a.ii) Renewable: Renewable energy resources shall be inventoried as the amount of usable energy extracted from nature. E.g. for solar electricity and heat this relates to the amount of electricity and/or heat captured by the solar cells (i.e. not the total solar energy, but what is delivered directly by the cells as electricity and/or usable heat)


not the total solar energy, but what is delivered directly by the cells as electricity and/or usable heat). For biomass from nature this is the amount physically embodied, measured as Lower calorific value, however of the water-free substance (i.e. measured as if the e.g. wood would be oven-dry). Note that biomass from fields and managed forests is no elementary flow. In that case, the named energy resources shall be inventoried directly as the respective elementary flows, e.g. "Solar energy" as "Renewable energy resources from air", expressed as Lower calorific value and measured in the reference unit MJ. I.b) Avoid geographical differentiation: Resources shall not be inventoried geographically differentiated (i.e. “Lignite” but not “Lignite, Eastern Germany”). This applies unless the selected LCIA method requires otherwise. (7.4.3.6.1) I.c) Chemical element resources: Resources for production of metals or other chemical elements should be inventoried as chemical element (e.g


(7.4.3.6.1) I.c) Chemical element resources: Resources for production of metals or other chemical elements should be inventoried as chemical element (e.g. “Iron - Resources from ground" elementary flow). (7.4.3.6.2) I.d) Functional/material resources: These shall be inventoried as target material resource (e.g. “Schist”, “Lime stone”, "Anhydrite"). Few exceptions exist where the mineral itself is in industry understood to be the target good; these are reflected in the ILCD reference elementary flows (e.g. "Rock salt", etc.). Other exceptions and exclusively for resources not included in the ILCD reference elementary flows shall be justified by following analogous logic. (7.4.3.6.2) I.e) Flows for completing mass balance: For completion of the mass balance, a


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results Provisions: 7.4.3.6 Resource elementary flows complementary amount of "Inert rock", "Water", or "Air" (or other, as applicable) shall be inventoried for extracted resources (e.g. 0.96 kg “Inert rock” in case of mining 1 kg copper ore with 4 % copper content). (7.4.3.6.2) I.f) No minerals or ore bodies: Inventorying of other minerals (unless these are functional / material resources such as “Granite”) or of specific ore bodies shall not be done (i.e. “Copper”, but not “Malachite” and not “Sulphidic copper-silver ore (3.5 % Cu; 0.20 % Ag)”). (7.4.3.6.2) Note that when applying the above rules double counting shall be avoided. Newly created elementary flows shall be checked whether they require carrying a characterisation factor for the applied LCIA method


Newly created elementary flows shall be checked whether they require carrying a characterisation factor for the applied LCIA method. II) SHALL - Land use and transformation: Direct land use and land transformation shall be inventoried along the needs of the applied LCIA method (if included in the impact assessment)149. (7.4.3.6.3) III) SHALL - Emissions from land use and transformation: If land use and/or land transformation are modelled, carbon dioxide and other emissions and related effects should be modelled as follows: [ISO!] III.a) Soil organic carbon changes from land use and transformation: For CO2 release from or binding in soil organic carbon (SOC) caused by land use and land transformation, the use of the most recent IPCC CO2 emission factors shall be used, unless more accurate, specific data is available. Detailed provisions and table with the IPCC factors: see chapter 7.4.4.1 and annex 13


Detailed provisions and table with the IPCC factors: see chapter 7.4.4.1 and annex 13. (7.4.3.6.3) III.b) Land use and transformation related CO2 emissions from biomass and litter: For virgin forests and for soil, peat, etc. of all land uses shall be inventoried as "Carbon dioxide (fossil)". Emissions from biomass and litter of secondary forests shall be inventoried as "Carbon dioxide (biogenic)". This applies unless the selected LCIA method requires otherwise. (7.4.3.6.4) III.c) Nutrient losses: Emissions of nutrients shall be modelled explicitly as part of the land management process. Detailed provisions see chapter 7.4.4.1. III.d) Other emissions: Other emissions in result of land transformation (e.g. emissions from biomass burning, soil erosion etc.) should be measured or modelled for the given case or using authoritative sources. Detailed provisions see chapter 7.4.4.1


emissions from biomass burning, soil erosion etc.) should be measured or modelled for the given case or using authoritative sources. Detailed provisions see chapter 7.4.4.1. (7.4.3.6.3) IV) MAY - Water use: It is recommended to differentiate at least: [ISO+] IV.a) on the input side: surface freshwater, renewable groundwater, fossil / deep ground water, sea water IV.b) on the output side: Emission/discharge of water in liquid form emission in form of steam 149 While this document has been finalised no established and globally applicable practice was available, but several approaches with either only regional applicability or lack of practice experience. These work with fundamentally different inventorying approaches. Any specific recommendation or requirement on inventorying land use and conversion would be implemented and published via revised ILCD reference elementary flows and recommended LCIA methods, and/or a revision of this document.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results Provisions: 7.4.3.6 Resource elementary flows IV.c) Other water quality changes, especially by chemical substances shall be inventoried as separate elementary flows. Note that if the above provisions cannot be fully met, this shall be explicitly considered when reporting achieved data quality and when interpreting the results of LCA studies. Note that LCI data sets' inventories that do not meet the above requirements are not compliant with the ILCD nomenclature. 7.4.3.7 Future processes and elementary flows (Refers to aspects of ISO 14044:2006 chapters 4.2.3.6.2 and 4.3.2.1) 7.4.3.7.1 Introduction and overview (Refers to aspects of ISO 14044:2006 chapters 4.2.3.6.2 and 4.3.2.1) The issue of future interventions (e.g


during the use-stage of long-living goods and their end-of-life-treatment, as well as delayed emissions from landfills) are addressed jointly with the issue of mid- and long-term removal of carbon dioxide from the atmosphere via storage in long-living bio-based goods as well as with the permanent removal in CO2 storages e.g. underground. The provisions on time-representativeness of processes that are operated in the future (e.g. recycling of long-living products) were already made in scope chapter 6.8.4. This present chapter focuses on complementary aspects of emissions that occur in the future


recycling of long-living products) were already made in scope chapter 6.8.4. This present chapter focuses on complementary aspects of emissions that occur in the future. 7.4.3.7.2 Differentiating the inventory of interventions in the more remote future (long-term emissions beyond 100 years) (Refers to aspects of ISO 14044:2006 chapters 4.2.3.5, 4.2.3.6.2 and 4.3.2.1) General Impacts from processes that run in the future but that are not (necessarily) man-managed but determined today (especially long-term emissions from landfills by leaching and landfill gas) need a convention to provide unambiguous decision support: These are to be modelled by separately inventorying emissions that occur within the next 100 years from the time of the LCI/LCA study (e.g. as “Emissions to water”) and those that occur beyond that time frame over an indefinite time (e.g. as “Emissions to water, unspecified (long-term)”)


as “Emissions to water”) and those that occur beyond that time frame over an indefinite time (e.g. as “Emissions to water, unspecified (long-term)”). For the long-term emissions it is hence implicitly assumed that no measures are taken by mankind to sanitize/encapsulate the landfill permanently. Note that the operation of the landfill (including e.g. post closure leachate treatment) will necessarily be modelled as implemented / operated today. LCIA of long-term emissions The emissions within the first 100 years are subject to the same LCIA impact assessment as are all other interventions from the system. The emissions beyond 100 years are not included into the general LCIA results calculation and aggregation, but are to be calculated, presented and discussed as separate LCIA results. This approach is evolving to be widely used


This approach is evolving to be widely used. It is important to note that this separate calculation does not indicate per se a lower relevance of long-term emissions; LCA is not including the discounting of future impacts unless this would be part of an explicit weighting. The logic for the separation of short-term and long-term emissions is that both have often fundamentally different uncertainty: emissions today can be measured, emissions from landfills in 100 years can only be roughly forecasted. At the same time, will the inventory of


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results landfills - if the emissions are modelled for e.g. 100,000 years - easily dominate the entire LCA results. This is important to know, but needs a separate interpretation. At the same time does this issue illustrate one weakness of LCA: LCIA methods usually do not account for thresholds, but aggregate all emissions over time. Hence even if the concentrations in the waste deposit leachate after 1,000 years might be below any eco-toxic effect, the total amount of these emissions over tenths of thousands of years will be summed up and be considered the same way as the same amount emitted at much higher concentrations over a few years


It could be argued that as/if landfills are environmentally relevant long-term emitters, mankind will eventually (potentially well before 100 years have gone by) dig them out to sanitize them and/or gaining back e.g. copper and other secondary resources from them. In summary: emissions within the next 100 years and beyond need a separate impact assessment and appropriate interpretation in view of their different certainty. 7.4.3.7.3 Temporary carbon storage, delayed greenhouse gas emissions, delayed credits for solving multifunctionality (Refers to aspects of ISO 14044:2006 chapters 4.2.3.5, 4.2.3.6.2 and 4.3.2.1) Inventorying and impact assessment of biogenic and fossil CO2 and CH4 Uptake of “Carbon dioxide” by plants shall be inventoried under “Resources from air”. Both the uptake of CO2 from the atmosphere and the release of both fossil and biogenic CO2 are assigned characterisation factors for the impact assessment


Both the uptake of CO2 from the atmosphere and the release of both fossil and biogenic CO2 are assigned characterisation factors for the impact assessment. The lack of knowledge whether a carbon dioxide or methane emission is biogenic or fossil (i.e. inventoried as "unspecfied") therefore does not render the results erroneous. The link between temporary CO2 removal, delayed emissions and the "Global Warming potential 100 years" The temporary removal of carbon dioxide from the atmosphere by incorporation into longliving bio-based products, into bio-based material remains in landfills, or in CO2-undergroundstorages is accounted for in the inventory. It is however not considered per default in the overall LCIA results calculation, as LCA per se is not discounting emissions over time150; this is unless the goal of the study would directly require that


The inventorying is done as follows: the duration for which LCIA impacts of released emissions is calculated, is typically explicitly or implicitly indefinite. Exclusively in case of the Global Warming Potential (GWP) the much shorter perspective “GWP 100 years” is widely used (details and recommendations are provided in the separate LCIA guidance documents of the ILCD Handbook). The related characterisation factors used are typically those provided as part of the Intergovernmental Panel on Climate Change (IPCC) reports. Climate change is hence implicitly considered to be a problem of the next 100 years (3 to 4 generations). The long-term removal of CO2 from the atmosphere and storage in long-living goods is hence politically promoted (see also further notes and aspects in footnote 152). The difficulty is that the GWP 100 relates to the effect after the emission has taken place i.e. it counts the climate change impact of emissions that occur nowadays exert within the next 100 years


The difficulty is that the GWP 100 relates to the effect after the emission has taken place i.e. it counts the climate change impact of emissions that occur nowadays exert within the next 100 years. However, these emissions may also occur in the future (in e.g. 80 years when a now newly built house is broken down). Assigning a full GWP 100 factor to these emissions that happen in 80 years would contradict the logic of the GWP 100 detailed above, as in that case their climate change effect for 180 years from now would be accounted for. 150 But see chapter 7.4.3.7.2 regarding long-term emissions that need a separate interpretation.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results Also, no incentive would exist to temporarily store the CO2 e.g. in the wooden beams of the house in the above example. On the other hand does temporary storage of CO2 and the delayed emissions not consider that the CO2 will in any case exert its full radiative effect, only later. For that reason carbon storage should only be considered quantitatively if this is explicitly required to meet the needs of the goal of the study. Otherwise, i.e. per default, temporary carbon storage and the equivalent delayed emissions and delayed reuse/recycling/recovery within the first 100 years from the time of the study shall not be considered quantitatively


Note that the provided inventorying solution allows to do both with the same data set, as the storage / delay information is inventoried as separate inventory item: Modelling / inventorying provisions and examples: To account for this and to at the same time ensure a transparent, plausible, and practiceapplicable life cycle inventory, the following provisions are made: As all emissions that occur within the next 100 years from the year of the analysis are inventoried as normal elementary flows, and all emissions that occur after 100 hundred years are inventoried as long-term emissions, simply a correction elementary flow of storage/delayed emission can be introduced for each contributing substance. For fossil carbon dioxide this flow is named "Correction flow for delayed emission of fossil carbon dioxide (within first 100 years)" as “Emissions to air”. It is measured in the flow property “Mass*years” and the reference unit “kg*a”


It is measured in the flow property “Mass*years” and the reference unit “kg*a”. The flow is to carry a GWP 100 impact factor of “-0.01 kg CO2-equivalents” per 1 kg*a. The information about the assumed time o emission and the actual amount of the emission shall be documented in the unit process and hence available for review. Flows for biogenic (i.e. temporarily stored) carbon dioxide and methane, but also for other, fossil greenhouse gases with delayed emissions can be developed analogously. These new elementary flows should be used in addition to the normal elementary flows including the flow “Carbon dioxide” as “Resources from air” that model the physical uptake of CO2 into biomass. A quantitative example: In the case of the above example of the end-of-life of a newly build house that is assumed to be demolished in 80 years, releasing the stored e.g


A quantitative example: In the case of the above example of the end-of-life of a newly build house that is assumed to be demolished in 80 years, releasing the stored e.g. 4 tons of carbon in the 10 tons of wood beams as CO2 would carry the following inventory flows and values:  Inputs: - 4,000*44/12 = 14,666 kg “Carbon dioxide” as “Resources from air”  Outputs: - 4,000*44/12 = 14666 kg “Carbon dioxide (biogenic)” as “Emissions to air” - 4,000*44/12*80 = 1,173,333 kg*a “Correction flow for delayed emission of biogenic carbon dioxide (within first 100 years)” as “Emissions to air” In an impact assessment the result would be calculated as follows, with the biological uptake and release of the carbon dioxide cancelling each other out151, giving a correct resulting GWP 100 benefit for the 80 years storage, as 1,173,333 kg*a * -0.01 kg CO2eq./(kg*a) = -11,733.33 kg CO2-eq. 151 Note that this works independently whether both have a GWP factor assigned or both not


151 Note that this works independently whether both have a GWP factor assigned or both not. That means that both modelling approaches can be supported by the mechanism of the CO2 temporary storage flow.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results Note that in the above example in total a negative Climate change effect is accounted for in the LCIA results, if considering the short-term perspective. If however the indefinite perspective would be considered, being the default perspective under the ILCD, the delayed emissions are not considered. Note that this approach is applicable also to wood from primary forests that is used as wood product for a certain time: in case the forest is effectively removed and e.g. a pasture established this loss of C-storage is already addressed via the provisions for land transformation, i.e. not accounting for the CO2 uptake from air. Equally is the calculation applicable to temporal storage of CO2 in landfilled bio-based materials


not accounting for the CO2 uptake from air. Equally is the calculation applicable to temporal storage of CO2 in landfilled bio-based materials. An example for delayed fossil CO2 emissions: In the case of a delayed emission of fossil greenhouse gases, for clarity assuming the above example of the house would have e.g. 4 tons of fossil carbon in it, e.g


4 tons of fossil carbon in it, e.g. in insulation material and window frames, the example looks as follows:  Inputs: - (none, as the CO2 is fossil)  Outputs: - 4,000*44/12 = 14,666 kg “Carbon dioxide (fossil)” as “Emissions to air” - 4,000*44/12*80 = 1,173,333 kg*a “Correction flow for delayed emission of fossil carbon dioxide (within first 100 years)” as “Emissions to air” In an impact assessment the result would be calculated as follows, with the correction for the delayed emissions partly (here by - 80 % as the storage time is 80 years) compensating the release of fossil CO2, giving a correct resulting GWP 100 result for the 80 years delayed emission, as 14,666 kg CO2-eq. + 1,173,333 kg*a * -0.01 kg CO2-eq./(kg*a) = +2,932.67 kg CO2-eq