+ 1,173,333 kg*a * -0.01 kg CO2-eq./(kg*a) = +2,932.67 kg CO2-eq. Hence, in comparison, the biogenic wood has still its full advantage of having extracted CO2 from the atmosphere, while the delayed emissions are a benefit that both systems have in common (note that the difference between both examples is 14666 kg CO2-eq.). The above works analogously with Nitrous oxide and other greenhouse gases. Note that for the use stage of long-living goods the inventory would contain the integral of the emissions at different ages. This can be simplified in the common case that the use stage emissions are the same for all years: the total amount of use stage emissions would be multiplied with half of the assumed life time years. The maximum amount of each correction flow that can be inventoried per kg delayed emission shall be 100 kg*a. That is if the delayed emission takes place exactly 100 years into the future


The maximum amount of each correction flow that can be inventoried per kg delayed emission shall be 100 kg*a. That is if the delayed emission takes place exactly 100 years into the future. The correction flow shall be inventoried only if the emission is forecasted to take place at a maximum of 100 years into the future from the time of study. It shall not be inventoried if the emission takes place beyond the 100 years : An emission that takes place more than 100 years into the future shall be reflected in the inventory exclusively by inventorying the future emissions with the long-term emission elementary flows such as e.g. “Carbon dioxide, biogenic (long-term)” as “Emissions to air”. I.e. in that case no correction flow is required but would be wrong (see footnote 155).

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 Substitution / crediting for general cases of multifunctionality and for reuse / recycling / recovery that take place in the future In analogy to rewarding delayed emissions of greenhouse gases with credits, also substitution when solving general cases of multifunctionality need to consider the delay, e.g. when crediting the benefit of a co-product that supersedes an alternative production. This is if the temporary storage is considered in the first place as it is required to meet the specific goal of the study. The provisions for delayed greenhouse gas emissions apply analogously, i.e. respective "Correction flows..." should be inventoried with negative values. This results in a positive value (i.e. additional impact) for the Climate change impacts


respective "Correction flows..." should be inventoried with negative values. This results in a positive value (i.e. additional impact) for the Climate change impacts. In analogy to treating general cases of multifunctionality, the delayed substitution for reused parts/goods, recycled materials and recovered energy needs to consider the delay. 7.4.3.7.4 Long-term storage of potential emissions beyond 100 years In the case the CO2-storage in goods, landfills or dedicated e.g. underground storages is longer than 100 years and the emission occurs somewhen in the future beyond 100 years, the maximum accountable CO2-removal of 100 years storage is inventoried as detailed above. The quasi-permanent storage of CO2 and generally of potential emissions in dedicated long-term storage forms (e.g


The quasi-permanent storage of CO2 and generally of potential emissions in dedicated long-term storage forms (e.g. injection into former natural gas fields) is accounted for by inventorying no emissions, if the respective storage form can "guarantee" according to current scientific knowledge, and under independent external and qualified expert review, that the substance is not emitted for at least 100,000 years (number set by convention). (Partial) emissions before that time are inventoried as long-term CO2-emission elementary flows; emissions within the first 100 years are inventoried as normal CO2 emissions. Provisions: 7.4.3.7 Future processes and elementary flows Implicitly differentiated for attributional and consequential modelling. V) SHALL - Separate inventory items for emissions more than 100 years into the future: Emissions and other elementary flows that occur beyond the next 100 years from the time of the LCI/LCA study shall be inventoried separately (e.g


as “Emissions to water, unspecified (long-term)”) from those that occur within the first 100 years (e.g. “Emissions to water, unspecified”). [ISO!] Note that the ILCD reference elementary flows include a set of such long-term emissions to air, water and soil. VI) SHALL - Uptake of “Carbon dioxide” by plants: This shall be inventoried under “Resources from air”. This applies to all photosynthetic organisms. [ISO!] Note that both the uptake of CO2 from the atmosphere and the release of both fossil and biogenic CO2 should be 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 e.g. "Carbon dioxide (unspecified)") therefore does not render the results erroneous


The lack of knowledge whether a carbon dioxide or methane emission is biogenic or fossil (i.e. inventoried as e.g. "Carbon dioxide (unspecified)") therefore does not render the results erroneous. VII) SHALL - Inventory temporary carbon storage and delayed GHG emissions: If "temporary carbon storage in bio-based goods" is considered, the temporary removal of carbon dioxide from the atmosphere, storage in long-living bio-based products or landfills, and delayed emission as CO2 or CH4 shall be modelled analogously to delayed emissions of fossil carbon dioxide and other greenhouse gases. The difference is that


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: 7.4.3.7 Future processes and elementary flows for fossil emissions the uptake from the atmosphere is not considered, but only the delayed emission152. See also chapter 9 on interpretation and note that the temporary storage shall only be considered if explicitly required to meet the specific goal of the study. If this is the case, it shall both be modelled as follows: [ISO+] VII.a) Special correction elementary flows shall be used to inventory the amount of CO2 that is emitted in the future. This can be both due to temporary storage as embodied biogenic carbon in long-living and land-filled bio-based goods and due to processes with fossil GHG emissions that take place in the future


This can be both due to temporary storage as embodied biogenic carbon in long-living and land-filled bio-based goods and due to processes with fossil GHG emissions that take place in the future. If this is done, the following correction flows shall be used: VII.a.i) “Correction flow for delayed emission of biogenic carbon dioxide (within first 100 years)” and "Correction flow for delayed emission of fossil carbon dioxide (within first 100 years)", respectively. Both as elementary flows and classified on the general level as "Emissions", measured in the reference flow property “Mass*years” of storage and the reference unit “kg*a”. Both flows shall carry a GWP100 impact factor of “-0.01 kg CO2equivalents” per 1 kg carbon dioxide and 1 year of storage/delayed emission; this exclusively if "temporary carbon storage" is considered in the study


VII.a.ii) “Correction flow for delayed emission of biogenic methane (within first 100 years)” and “Correction flow for delayed emission of fossil methane (within first 100 years)”, respectively. Both as elementary flow and classified on the general level as "Emissions", measured in the reference flow property “Mass*years” of storage and the reference unit “kg*a”. Both flows shall carry a GWP100 impact factor of “-0.25153,154 kg CO2152 The logic behind accounting for biogenic carbon storage is that for the duration of storage the CO2 is not exerting a radiative forcing. This makes sense only in case near-term radiative forcing is considered more relevant than future radiative forcing, as the later re-emitted biogenic CO2 will still exert its full radiative forcing effect, only later. That is reflected by the commonly used one hundred years perspective for GWP100: the higher radiative forcing per unit (kg) of e.g


That is reflected by the commonly used one hundred years perspective for GWP100: the higher radiative forcing per unit (kg) of e.g. Methane and Nitrous oxide is weighted higher then the relatively lower radiative forcing per unit of CO2, always for 100 years. To reward the temporary removal of CO2 from the atmosphere is fully equivalent to the effect of avoided radiative forcing due to delayed emission of fossil carbon dioxide, methane, nitrous oxide, and other greenhouse gases: While the uptake of CO2 from the atmosphere is unique for biomass and considered in the impact assessment as negative impact, it does not matter whether one burns a block of wood or of plastic and releases the CO2 as emission: both biogenic and fossil CO2 are identically contributing to radiative forcing when emitted. For Climate change it is the same whether one keeps a piece of wood or of plastic unburned for e.g. 60 years


For Climate change it is the same whether one keeps a piece of wood or of plastic unburned for e.g. 60 years. If the time when an emission takes place is considered for biomass it must also be considered for fossil materials. Some examples/aspects: Note that on a net basis temporarily stored biogenic carbon has a negative Climate Change impact: at 60 years storage of e.g. 1 kg CO2: CO2 uptake (negative value -1 kg CO2-eq.) plus emission after 60 years (+1 kg CO2-eq.) minus the credit for 60 years temporary storage, = -1 + 1 - 0.6 = -0.6 kg CO2-equiv. in total. For delayed fossil emissions the net impact is always positive: CO2 emission minus credit for 60 years delayed emission, e.g. for 1 kg CO2 = 1 - 0.6 = 0.4 kg CO2-equiv. in total. Note that the difference between biogenic and fossil delayed emissions for the same time of delay is always the same (i.e. 1 kg CO2-equiv. difference per kg CO2 emitted), rewarding both biogenic carbon storage and long-living products


1 kg CO2-equiv. difference per kg CO2 emitted), rewarding both biogenic carbon storage and long-living products. 153 This factor uses the IPCC GWP100 factors of 2007 by multiplying the base-value for carbon dioxide of 0.01 with the substance-specific factor (e.g. 25 for methane, 298 for nitrous oxide (laughing gas, N2O)). The substance-specific factor shall be adjusted in line with any ILCD recommendations on LCIA methods or updated factors from the IPCC if the former is not available.


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: 7.4.3.7 Future processes and elementary flows equivalents” per 1 kg methane and 1 year of delayed emission; this exclusively if "temporary carbon storage" is considered in the study. VII.a.iii) “Correction flow for delayed emission of nitrous oxide (within first 100 years)”. As elementary flow and classified on the general level as "Emissions", measured in the reference flow property “Mass*years” of storage and the reference unit “kg*a”. This flow is to carry a GWP100 impact factor of “-2.98153 kg CO2-equivalents” per 1 kg nitrous oxide and 1 year of delayed emission; this exclusively if "temporary carbon storage" is considered in the study. VII.a.iv) For other greenhouse gases analogous factors can be developed and used


VII.a.iv) For other greenhouse gases analogous factors can be developed and used. VII.b) The maximum amount of each correction flow that can be inventoried per kg delayed emission shall be 100 kg*a. That is if the delayed emission takes place exactly 100 years into the future. The correction flow shall be inventoried only if the emission is forecasted to take place at a maximum of 100 years into the future from the time of study. It shall not be inventoried if the emission takes place beyond the 100 years155: An emission that takes place more than 100 years into the future shall be reflected in the inventory exclusively by inventorying the future emissions with the long-term emission elementary flows such as e.g. “Carbon dioxide, biogenic (long-term)” as “Emissions to air”. I.e. in that case no correction flow is required but would be wrong


“Carbon dioxide, biogenic (long-term)” as “Emissions to air”. I.e. in that case no correction flow is required but would be wrong. VIII) SHALL - Inventory future substitution analogous to delayed emissions: The provisions for delayed greenhouse gas emissions as detailed above apply analogously for delayed reuse/recycling/recovery in case this is modelled with substitution. The same applies generally for substitution that occurs in the future. The respective "Correction flows..." shall be inventoried with negative values, i.e. debiting for the delay in the substitution. Note that only if "temporary carbon storage and delayed emissions" is required to meet the specific goal of the study the correction flows will be considered and result in an additional contribution to the Climate change impacts


[ISO+] IX) SHALL - Document details and assumptions on delayed emissions / substitution: The information about the assumed storage time or time of future reuse/recycling/recovery and other cases of substitution, as well as the amounts and substances of the emissions in the unit process shall be documented and made available for review. [ISO+] X) SHALL - Provision for long-term / quasi-permanent storage of potential emissions: The quasi-permanent storage of CO2 and other potential emissions in 154 Note that both fossil and biogenic Methane carry the same factor, as the uptake of the CO2 by the plants is to be modelled explicitly in any case (see chapter 7.4.3.6.4) and the elementary flow carries a GWP factor of -1 kg CO2-equiv. per kg CO2 uptake. Fossil and biogenic Methane would require different factors only if the uptake would not be modelled explicitly


per kg CO2 uptake. Fossil and biogenic Methane would require different factors only if the uptake would not be modelled explicitly. 155 The reason is that otherwise the LCIA results for the short-term perspective (first 100 years) would carry a full credit of negative climate change impacts while the long-term LCIA results carry the emission as it takes place beyond 100 years. If in results interpretation a short-term perspective is taken (and the long-term emissions excluded / discounted) an incorrect negative impact would be found.


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: 7.4.3.7 Future processes and elementary flows dedicated long-term storage forms (e.g. injection into former natural gas fields) shall be accounted for by inventorying no emissions at all, if the respective storage form can guarantee that it is not emitted to the atmosphere for at least 100,000 years (duration set by convention). [ISO+] XI) SHALL - Document details and assumptions on long-term / quasi-permanent storage: The information about the storage form and assumed storage time shall be concisely documented and made available for review. This documentation shall be done via a respective waste inventory flow. [ISO+] Note: The other inventory work is done as usual: I.e. inventorying emissions that occur within 100 years from present with the normal elementary flows (e.g


[ISO+] Note: The other inventory work is done as usual: I.e. inventorying emissions that occur within 100 years from present with the normal elementary flows (e.g. “Methane, biogenic” as “Emissions to air”). Note that only if "temporary carbon storage" is considered in the study, in the later interpretation the results shall be analysed individually with and without the credit, showing explicitly the effect of the credit for storage/delayed emissions. 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. 7.4.3.8 Reminder flows (No corresponding ISO 14044:2006 chapter) Introduction and overview Reminder flows are no own category of flows, but an additional classification applicable to any flow


7.4.3.8 Reminder flows (No corresponding ISO 14044:2006 chapter) Introduction and overview Reminder flows are no own category of flows, but an additional classification applicable to any flow. It is excluding it from the impact assessment and system modelling, while keeping it in the inventory as a “reminder” also when creating LCI results. Reminder flows can be used for product flows such as "electricity, reminder flow" to keep the information in the LCI results what is the overall amount of electricity used over the life cycle. Such is sometimes required for certain life cycle applications such as Environmental Product Declarations (EPD). Or it can be used for indicator flows such as “VOC, reminder flow, not impact relevant” that is inventoried in addition to the single emissions which it is composed of. Presently “reminder flows” are used in few LCA software systems and databases, but this approach is seen very beneficial, as explained above


Presently “reminder flows” are used in few LCA software systems and databases, but this approach is seen very beneficial, as explained above. It is implemented as an option in the ILCD reference format where individual Input/Output flows can be marked as "Reminder flow". It is to be stressed again that reminder flows do not have any relevance regarding classical LCI results or LCIA results information, i.e. must not carry any LCIA impact factors and are not to be connected with up-stream or down-stream processes. Such reminder flows should have an own, specific name to lower the risk of double counting in the inventory. Provisions: 7.4.3.8 Reminder flows I) MAY - Use reminder flows to keep original information for specific purposes: It is recommended to use reminder flows to inventory the original information of split measurement indicators and sum flows (see 7.4.3.2). They may be used to keep other


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results flows in LCI results inventories for information purposes. [ISO+] II) SHALL - Exclude reminder flows from impact assessment: Reminder flows shall not carry an LCIA impact factor. [ISO+] III) SHALL - Clearly identify reminder flows in the flow name: The fact of being a reminder flow shall also be identified in the flow name (e.g. “VOC, reminder flow, not impact relevant”). [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. 7.4.4 Overarching method provisions for specific process types (Refers to aspects of ISO 14044:2006 chapters 4.2.3.5 and 4.3.2.2) 7.4.4.1 Modelling agro- and forestry systems (Refers to aspects of ISO 14044:2006 chapters 4.2.3.3.3 and 4.2.3.5) Introduction Industrial production processes typically have a well defined and controlled boundary between the technosphere and the ecosphere and are operated with equally well-defined or at least controlled (and hence measurable) operational parameters. Agricultural, forestry and similar (e.g. fish farming) production systems largely lack this. They therefore typically need to include different, model-based approaches for data collection


Agricultural, forestry and similar (e.g. fish farming) production systems largely lack this. They therefore typically need to include different, model-based approaches for data collection. The common needs of these systems of the economy's primary sector need specific guidance on some specific aspects: System boundaries Similar to modelling waste, also for agricultural and forestry systems the interpretation of the system boundary differs in LCA practice: a clear separation between emissions to soil, water and air in inventories of agricultural and forestry production requires a clear guidance in inventorying, separating correctly and consistently between the technosphere and the ecosphere: Pesticide and fertilizer applications are no emission, but part of the product flows within the (man-managed) technosphere. The emissions are the flows form the e.g. field or forest to the ecosphere via leaching and run-off of e.g


The emissions are the flows form the e.g. field or forest to the ecosphere via leaching and run-off of e.g. Nitrates and Phosphate, off-drift of pesticides during application and their volatilisation from plant and soil surface etc. The amount of these emissions has to be modelled case-specific as they can differ extremely: plant-uptake, site-properties, climate and geographical conditions, as well as farming practice determine the conversion of e.g. applied Ammonium nitrate fertiliser to nitrate emissions to water and to NH3 and N2O emissions to air. Equally the uptake of heavy metals into the harvested goods and removal from the site are elementary flows and are to be inventoried individually for the given case. At the same time, some inputs to soil do not leave the technosphere via leaching etc., but are accumulated in the soil, such as e.g. cadmium that typically accompanies most phosphate fertilisers at least to some extent. The amount of e.g


cadmium that typically accompanies most phosphate fertilisers at least to some extent. The amount of e.g. cadmium within the phosphate fertiliser that is applied to the field is directly inventoried as emission to agricultural soil.


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 a part of the nutrients from fertilisation may remain in the field after harvest and serves as input to the next crop, hence crosses the system boundary within the technosphere over time. In this case the substance is a co-function of the preceding crop, making that process multi-functional. The general provisions for solving multifunctionality apply. Net accumulation or depletion of a substance is hence to be recorded in the inventory, disregarding the nature of this substance (agrochemical, nutrient, heavy metal, carbon, etc.) and to be correctly considered in the system model or the impact assessment, as applicable


Carbon stock changes and CO2 emissions resulting from land use and land transformation Land transformation and land use often change the amount of soil organic carbon: after transformation from land occupations with higher soil organic carbon (e.g. forests) to those with a lower level (e.g. agriculture), over a number of years a new equilibrium is reached156. The differences in soil organic carbon is mostly emitted as CO2. In turn, land use changes can also result in net accumulation of soil organic carbon, which is sequestered from the air as CO2. To account for that effect and for the release/binding of climate change related gases (especially CO2, but potentially others) caused by land use and land use changes, the most recent data and emission factors provided by the Intergovernmental Panel on Climate Change (IPCC) should be used, unless more accurate, specific data is available. For calculating these IPCC-based factors from the basic land use information (e.g


For calculating these IPCC-based factors from the basic land use information (e.g. climate zone, soil type, land use type, etc.), guidance, data, and default factors related to CO2 emissions / binding are given in annex 13. The following text provides guidance on assigning or sharing the inventory to the land uses' functions after the transformation: The land use transformation related direct and indirect inventory (e.g. machine use, peak emissions occurring e.g. when the forest biomass is incinerated, long-term CO2 emissions from soil carbon) shall be allocated to the land use functions (e.g. crops) of the following years by area and year. Two cases are to be differentiated:  a) inventory items that occur over a longer period than one year (e.g. CO2 emissions from loss of soil organic carbon due to biodegradation of e.g. humus)  b) inventory items that occur in direct context of the transformation and not longer than one year afterwards (e.g


humus)  b) inventory items that occur in direct context of the transformation and not longer than one year afterwards (e.g. machine use during conversion and peak emissions e.g. from biomass burning) For case a), and for both attributional and consequential157 models, the inventory should be assigned to the land use functions in proportion to the inventory that occurs during the 156 It is important to note that each even minor change in land use (e.g. cropping wheat where the year before sugar beets were cropped) is formally a land transformation. It depends on how different the uses are, whether they effectively result in changes e.g. of the long-term soil organic carbon equilibrium. The following examples are assuming that for the different crops named to be produced after transformation, do not change this equilibrium, i.e. do not imply each another land transformation. Otherwise, a new transformation step would need to be calculated


do not imply each another land transformation. Otherwise, a new transformation step would need to be calculated. This would then need to consider that the equilibrium has not yet been achieved and hence start with the interim achieved soil organic carbon level and considering the new equilibrium for the next land use. To work out the details might be a topic e.g. for a sector-specific guidance document or Product Category Rule (PCR). 157 Note that indirect land use changes are a topic under detailed consequential modelling; see chapter 7.2.4.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results time the land use function is occupying the land or otherwise blocking it for other uses (e.g. 1 year fallow as part of crop rotations). For loss / binding of CO2 in form of soil organic carbon, towards reaching the equilibrium of the land use after transformation, a default period of 20 years shall be assumed (see Formula 1). This is, unless it can be demonstrated that the period during which about 90 % the main losses / binding occurs is significantly longer or shorter for the given case. In that case, that duration shall be applied and Formula 2 be used. For simplification, the total loss shall be assumed be to occur linearly with time over the period until the about 90 % loss / binding towards the new equilibrium have been reached; this is assumed, as said above, to occur per default over 20 years. I.e


I.e. a triangle-shaped allocation pattern shall be used over the considered years (as expressed in Formula 1). This approach is giving higher burdens to the first years after transformation. This is motivated under consequential modelling by the closer link to the decision to convert that land. Under attributional modelling, the reasoning is that that amount is inventoried, which physically occurs158 in the period of the land use (including periods of blocking it for other uses). If the initial years after transformation are without harvest (e.g. as typical for in plantations), the inventory shall be assigned to the first harvest / function of the land use after transformation. If only one kind of crop is harvested (e.g. fruits of a 25 year running fruit tree plantation without wood use), the entire inventory can be allocated to the total amount of the crop, independently of the specific year when the crop has been harvested; i.e. each kg has the same inventory


each kg has the same inventory. In the case more than one crop is harvested per year, the calculated inventory for that year (see below) shall be linearly allocated between these crops over the time of that year that they use the land or block it for other uses; i.e. for simplification no further differentiation needs to bee made between months earlier and later in that year. If the land use function (e.g. harvesting of wood) occurs after the considered period (here: 20 years), the entire inventory shall be assigned to that function, i.e. not only the share of that year, i.e. the inventory of preceding years is assigned to the crops harvested later, as otherwise it would be lost / not accounted for. If a joint production e.g. of annual crops and a final crop occurs (e.g. latex during the years and rubber wood at the end), the final crop should be considered to have been harvested after half the total period


of annual crops and a final crop occurs (e.g. latex during the years and rubber wood at the end), the final crop should be considered to have been harvested after half the total period. The % share of the total inventory that shall be allocated to a given year (assuming the crop occupies that land for the full year or otherwise prevents its use for a full year), is then calculated using Formula 1. Formula 1 * * i X  X = % of inventory to be allocated to the year i of the analysed crop  20 = number of years after transformation over which the inventory is to be allocated, i.e. until when 90 % of the losses / bindings of the CO2 from / into the soil have occurred. The number of years is counted from the transformation onwards. 158 It is noted that the actual distribution over time is about exponential. The triangle is hence a simplification.


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 = number of years after transformation during which the analysed crop is cropped; the first year after transformation is year i = 0 (Additional condition: if i > 20-1 then X = 0, i.e. nothing shall be allocated after 20 years). Example: After transformation of a former land use to permanent agriculture, after 2 years the first crop might be harvested (e.g. pineapple). In year 3 e.g. corn is harvested, and in year 4 e.g. papaya. Applying Formula 1, the pineapple receive for the first year (100*2)/(20+1)*(20-0)/20 % = 200/21*1 % = 9.5 % plus for the second year (100*2)/(20+1)*(20-1)/20 % = 200/21*0.95 % = 9 %, in sum 18.5 % of the total CO2 inventory related to the transformation


The corn of year 3 receives (100*2)/(20+1)*(20-2)/20 % = 200/21*0.9 % = 8.6 %, the papaya of year 4 (100*2)/(20+1)*(20-3)/20 % = 200/21*0.85 % = 8.1 %, and so on. In sum over 20 years, 100 % are assigned to the various land use functions. For land uses during the considered period but that are shorter than one year, the inventory shall be linearly shared among the uses according to their duration of using or blocking the land. The data, tables, factors and formula for calculating this CO2 inventory that is to be shared as detailed above, is given in annex 13. For case b), and both under attributional and consequential modelling: the subsequent years of land use e.g. for agriculture of different crops can be considered to be analogous to the reuse/further use e.g. of refillable bottles or recycled metals. I.e. they each share the same share of the "production" inventory (here: the land transformation) per function (here: year of land use)


of refillable bottles or recycled metals. I.e. they each share the same share of the "production" inventory (here: the land transformation) per function (here: year of land use). Also under consequential modelling, the reuse/further use of the land leads to the same burdens are shared per function provided (see the example on further use of a metal table in the "Terms and concepts: Recyclability substitution approach" box in annex 14.5.2). Per default and set as convention for sub-annual, annual and bi-annual crops, the total amount of uses over which the "production" inventory of the land transformation is to be shared shall be 20 years159. This is the same duration over which by default the soil organic carbon changes are modelled. This is unless the foreseeable duration of the transformed land use is shorter, ending foreseeably with nature or no use other than short-term/managed fallow (e.g. slash-and-burn agriculture of 3 years use before abandoning)


slash-and-burn agriculture of 3 years use before abandoning). Or the foreseeable minimum use is longer (e.g. plantations with 30 years plantation cycle). In that case, that duration of one plantation / use cycle shall be used. The % share of the total inventory that shall be assigned to a given year of land use (assuming the crop occupies that land for the full year or otherwise prevents its use for a full year), is then proportional to the duration of land use / blocking it for other uses. I.e. other than for the preceding case of soil carbon changes it does not depend how long after transformation the land use occurs, as long as it is within the period that is considered as defined above160. 159 This and the following settings assume that the decision to change the land use is not motivated for the next single crop year, but over a longer period


159 This and the following settings assume that the decision to change the land use is not motivated for the next single crop year, but over a longer period. 160 The reasoning that the emissions that occur in year 0 are linearly shared by the following land uses over several years, while the emissions that occur over a longer period are shared in a triangular shape, i.e. giving a higher share to the land use directly following the transformation, is as follows: The "peak" inventory of transformation is equivalent to a production inventory, e.g. of a refillable bottle. The emissions that occur over a longer period are still related to the transformation, but it depends on the specific land use in a given year, whether the e.g. soil organic carbon loss is stopped by e.g. better land management, i.e. is an operational emission (similar to washing a refillable bottle). Hence it is to be inventoried as and when it occurs.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results Example: if the agricultural production of slash-and-burn for three years' harvests bananas in the first year and manioc in the second and cassava in the third year, the harvests of bananas, manioc and cassava receive each 1/3 = 33.3 % of the inventory (assuming here for simplification that they use the land each for one year. For both cases a) and b): In the case of co-products, the same provisions apply as for general cases of multifunctionality under attributional modelling (see chapter 7.9) and consequential modelling (see chapter 7.2.4.6), respectively. If the natural goods from the converted land (e.g. wood) are also at least partly used, they shall be considered one function as part of the multifunctional system


If the natural goods from the converted land (e.g. wood) are also at least partly used, they shall be considered one function as part of the multifunctional system. The same provisions apply analogously to land transformation between other than agricultural, pastoral or forestry uses. The focus is put here on these processes, as for these the effects or often highly relevant for the LCI results. Other emissions resulting from land use and land transformation (with equilibrium, excluding nutrients) Other emissions that occur over a longer period than one year after transformation, but similar as the soil organic carbon in an exponential way, should be measured or modelled for the given case or using authoritative sources with generic data if available. This formula is also used if under case "a)" 90 % of the equilibrium of the soil organic carbon is reached after more or less then the 20 years that are set per default (see more above in this chapter)


The % share of the total inventory that shall be assigned to a given year (assuming the crop occupies that land for the full year or otherwise prevents its use for a full year), is then calculated using Formula 2, being the general form of Formula 1: Formula 2 n i n n X * *  X = % of inventory to be allocated to the year i of the analysed crop  n = number of years after transformation over which the inventory is to be allocated, i.e. until when 90 % of the losses / bindings have occurred. The number of years is counted from the transformation onwards.  i = number of years after transformation during which the analysed crop is cropped; the first year after transformation is year i = 0 (if i > n-1 then X = 0, i.e. nothing shall be allocated after the number of considered years). Example: Inventorying the XY leaching losses after land transformation of tropical forest by slash-and-burn agriculture: 90 % of the leaching may occur over 3 years (value illustrative only)


Example: Inventorying the XY leaching losses after land transformation of tropical forest by slash-and-burn agriculture: 90 % of the leaching may occur over 3 years (value illustrative only). In these three years, the following is cropped and harvested: bananas in the first year, and manioc in the second year, and cassava in the third year. The bananas harvest receives (100*2)/(3+1)*(3-0)/3 % = 50*1 % = 50 % of the total inventory related to the transformation. The manioc of the second year receives (100*2)/(3+1)*(3-1)/3 % = 50*(2/3) % = 33.3 % and the cassava (100*2)/(3+1)*(3-2)/3 % = 50*(1/3) % = 16.7 %, in sum 100 %. Note that the total amount of the loss of XY and the actual duration of the main losses until about 90 % of the equilibrium of the land use are reached need to be identified first. Emissions without an equilibrium Emissions that do not have an equilibrium or that reach that state in a not exponential way, (e.g


Emissions without an equilibrium Emissions that do not have an equilibrium or that reach that state in a not exponential way, (e.g. soil erosion) need to be modelled differently, while following an analogous


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results reasoning as the other inventory items addressed in this chapter. E.g. surface erosion by water and wind and related mass flow transfer of these substances together with the eroded soil to waterways or air shall be inventoried as "Emission to fresh water" or "Emission to air", respectively. These losses are directly related to the operation of the cropping process, hence belong to its inventory. Nutrients as emissions and as product flows Note that emissions especially of NO3 -, PO4 3- and other substances that are part of the nutrient system of the land and crop should be modelled as they occur during the respective land use. In fact are these nutrients a product flow input from the preceding land use and hence a co-function that needs to be solved as other cases of multifunctionality


In fact are these nutrients a product flow input from the preceding land use and hence a co-function that needs to be solved as other cases of multifunctionality. Any remaining nutrients such as nitrate in the field are a co-product of the crop are an input for the production of the next crop. These cases of multifunctionality shall be solved in principle via system expansion (consequential modelling) or allocation (attributional modelling), applying the same provisions are foreseen for other cases of multifunctionality; see 7.2.4.6 and 7.9, respectively. Temporary removal of carbon dioxide from the atmosphere by plants and release at end-of-life See chapter 7.4.3.7.3. Indirect land use changes 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. Provisions: 7.4.4.1 Modelling agro- and forestry systems Applicable to Situation A, B, and C, differentiated


Provisions: 7.4.4.1 Modelling agro- and forestry systems Applicable to Situation A, B, and C, differentiated. Differentiated for attributional and consequential modelling. I) SHALL - Agro- and forestry systems: Their modelling shall be done as follows: [ISO!] I.a) Inventory net interventions: Only the net interventions related to human land management activities shall be inventoried. Interventions that would occur also if the site was unused shall not be inventoried (e.g. not the basic Nitrate leaching resulting from N input via rain): I.a.i) Reference system under attributional modelling: The "no use" reference system shall be the independent behaviour of the site, starting from the status of the land at that moment when the area of the analysed system is prepared for the modelled system


I.a.ii) Indirect land use under consequential modelling: The indirect land use (mix) shall be modelled (provisions see chapter 7.2.4.4); net interventions may need to be modelled for those indirect land uses / transformations. Note that land transformation happening in the past may need to be allocated to the analysed system. I.b) Model site as part of the technosphere: Of the applied fertilisers and agrochemicals (e.g. fungicides) only the amounts that leave the site (i.e. the field, plantation, managed forest etc.) shall be inventoried as emissions to air or 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 Provisions: 7.4.4.1 Modelling agro- and forestry systems as appropriate. I.c) Carried over nutrients as co-functions: Any remaining nutrients such as N in crop residues are a co-product of the crop are an input for the production of the next crop. These cases of multifunctionality shall be solved in principle via system expansion (consequential modelling) or allocation (attributional modelling), applying the same provisions are foreseen for other cases of multifunctionality; see 7.2.4.6 and 7.9, respectively. Also emissions especially of Nitrate, Phosphate and other substances that are part of the nutrient system of the land and crop should be modelled as they occur during the respective land use


Also emissions especially of Nitrate, Phosphate and other substances that are part of the nutrient system of the land and crop should be modelled as they occur during the respective land use. I.d) Model immobile substances to cross the system boundary over time: Strongly soil-bound heavy metals and Persistent Organic Pollutants (POPs) that remain in the site for many decades shall be inventoried as “Emissions to soil, unspecified”. Leaching of these substances to the groundwater shall not be inventoried additionally, but is covered via the impact assessment of this emission to soil. In contrast, surface erosion by water and wind and related mass flow transfer of these substances together with the eroded soil to waterways or air shall be inventoried as "Emission to fresh water" or "Emission to air", respectively. These losses are directly related to the operation of the cropping process, hence belong to its inventory


These losses are directly related to the operation of the cropping process, hence belong to its inventory. Note that the amount inventoried as emission to soil is to be reduced by the respective erosive losses. Double-counting shall be avoided. I.e) Model emissions form land use and transformation: Carbon dioxide and other emissions resulting from land use and land transformation shall be modelled as follows, for both attributional and consequential modelling: I.e.i) CO2 emissions: These shall be calculated using the most recent Intergovernmental Panel for Climate Change (IPCC) factors per default, unless more accurate, specific data is available. Other, relevant inventory items should be measured or modelled for the given case or using similar authoritative sources, if available. Formulas for assignment to different subsequent land uses see below. The data, tables, factors and formula for calculating this CO2 inventory that is to be shared as detailed below, is given in annex 13


The data, tables, factors and formula for calculating this CO2 inventory that is to be shared as detailed below, is given in annex 13. I.e.ii) Two cases of inventory related to land transformation: The land transformation related direct and indirect inventory shall be allocated to the following crops by used/occupied land area and duration of cropping, as follows. Two cases are to be differentiated: a) inventory items that occur over a longer period than one year, exponentially reaching a new quasi-equilibrium (e.g. CO2 emissions from loss of soil organic carbon due to biodegradation of e.g. humus). b) inventory items that occur in direct context of the transformation and not longer than one year afterwards (e.g. machine use during conversion and peak emissions e.g


humus). b) inventory items that occur in direct context of the transformation and not longer than one year afterwards (e.g. machine use during conversion and peak emissions e.g. from biomass burning) I.e.ii.1) For case a), and for both attributional and consequential models, the inventory should be assigned to the land use functions in proportion to the inventory that occurs during the time the land use function is occupying the land or otherwise


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: 7.4.4.1 Modelling agro- and forestry systems blocking it for other uses (e.g. include 1 year fallow as part of crop rotations). For loss / binding of CO2 in form of soil organic carbon, towards reaching the equilibrium of the land use after transformation, a default period of 20 years shall be assumed. This is meant to reflect about 90 % the main losses / binding. I.e.ii.2) For simplification, the total loss shall be assumed to occur in a triangularly shaped distribution with time over the period until the about 90 % loss / binding towards the new equilibrium have been reached. Formula 1 shall be used to allocate the calculated total emission/binding to the crops; if the above default period can be demonstrated to be different from 20 years, Formula 2 shall be used instead


Formula 1 shall be used to allocate the calculated total emission/binding to the crops; if the above default period can be demonstrated to be different from 20 years, Formula 2 shall be used instead. I.e.ii.3) Formula 1 * * i X  X = % of inventory to be allocated to the year i of the analysed crop  20 = number of years after transformation over which the inventory is to be allocated, i.e. until when 90 % of the losses / bindings of the CO2 from / into the soil have occurred. The number of years is counted from the transformation onwards.  i = number of years after transformation during which the analysed crop is cropped; the first year after transformation is year i = 0 (Additional condition: if i > 20-1 then X = 0, i.e. nothing shall be allocated after 20 years). I.e.ii.4) If the initial years after transformation are without harvest (e.g. as typical for in plantations), the inventory shall be assigned to the first harvest / function of the land use after transformation


as typical for in plantations), the inventory shall be assigned to the first harvest / function of the land use after transformation. I.e.ii.5) If only one kind of crop is harvested (e.g. fruits of a 25 year running fruit tree plantation without wood use), the entire inventory can be allocated to the total amount of the crop, independently of the specific year when the crop has been harvested; i.e. each kg has the same inventory. I.e.ii.6) In the case more than one crop is harvested per year, the calculated inventory for that year shall be linearly allocated between these crops over the time of that year that they use the land or block it for other uses; i.e. for simplification no further differentiation needs to bee made between months earlier and later in that year. I.e.ii.7) If the land use function (e.g. harvesting of wood) occurs after the considered period (here: 20 years), the entire inventory shall be assigned to that function, i.e. not only the share of that year, i.e


harvesting of wood) occurs after the considered period (here: 20 years), the entire inventory shall be assigned to that function, i.e. not only the share of that year, i.e. the inventory of preceding years is assigned to the crops harvested later, as otherwise it would be lost / not accounted for. I.e.ii.8) If a joint production e.g. of annual crops and a final crop occurs


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: 7.4.4.1 Modelling agro- and forestry systems (e.g. latex during the years and rubber wood at the end), the final crop should be considered to have been harvested after half the total period. I.e.ii.9) The % share of the total inventory that shall be allocated to a given year (assuming the crop occupies that land for the full year or otherwise prevents its use for a full year), is then calculated using Formula 1 (see above). I.e.ii.10) For land uses during the considered period but that are shorter than one year, the inventory shall be linearly shared among the uses according to their duration of using or blocking the land


I.e.ii.11) For case b) and per default for sub-annual, annual and biannual crops, the total amount of uses over which the "production" inventory of the land transformation is to be shared shall be 20 years. This is unless the foreseeable duration of the transformed land use is shorter, ending foreseeably with nature or no use other than short-term/managed fallow (e.g. slashand-burn agriculture of 3 years use before abandoning). Or the foreseeable minimum use is longer (e.g. plantations with 30 years plantation cycle). In that case, that duration of one plantation / use cycle shall be used. I.e.ii.12) The % share of the total inventory that shall be assigned to a given year of land use (assuming the crop occupies that land for the full year or otherwise prevents its use for a full year), is then proportional to the duration of land use / blocking it for other uses. I.e


I.e. other than for the preceding case of soil carbon changes it does not depend how long after transformation the land use occurs, as long as it is within the period that is considered as defined above. I.e.ii.13) Other emissions resulting from land use and land transformation (with equilibrium, excluding nutrients): I.e.ii.14) Other emissions that occur over a longer period than one year after transformation, but in an exponential way, should be measured or modelled for the given case or using authoritative sources with generic data if available. The following Formula 2 can be applied, being the general form of Formula 1: I.e.ii.15) The % share of the total inventory that shall be assigned to a given year (assuming the crop occupies that land for the full year or otherwise prevents its use for a full year), is then calculated using Formula 2


I.e.ii.16) Formula 2 n i n n X * *  X = % of inventory to be allocated to the year i of the analysed crop  n = number of years after transformation over which the inventory is to be allocated, i.e. until when 90 % of the losses


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: 7.4.4.1 Modelling agro- and forestry systems / bindings have occurred. The number of years is counted from the transformation onwards.  i = number of years after transformation during which the analysed crop is cropped; the first year after transformation is year i = 0 (if i > n-1 then X = 0, i.e. nothing shall be allocated after the number of considered years). I.e.ii.17) Note that the total amount of the loss of XY and the actual duration of the main losses until about 90 % of the equilibrium of the land use are reached need to be identified first. I.e.ii.18) Emissions of items without an equilibrium: I.e.ii.19) Emissions that do not have an equilibrium state or that reach that state in a not exponential way, (e.g


I.e.ii.18) Emissions of items without an equilibrium: I.e.ii.19) Emissions that do not have an equilibrium state or that reach that state in a not exponential way, (e.g. soil erosion) need to be modelled differently, while following an analogous reasoning as the other inventory items addressed in this chapter. These losses are directly related to the operation of the cropping process, hence belong to its inventory. I.e.iii) If the natural goods from the converted land are also at least partly used (e.g. harvested primary forest wood), they shall be considered one function as part of the multifunctional system. I.e.iv) The same provisions apply analogously to land transformation between other than agricultural, pastoral or forestry uses. I.e.v) Emissions that do not have an equilibrium state or reach that state in a not exponential way, (e.g. soil erosion) need to be modelled differently, while following an analogous reasoning as the other inventory items addressed in this chapter


soil erosion) need to be modelled differently, while following an analogous reasoning as the other inventory items addressed in this chapter. Temporary removal of carbon dioxide from the atmosphere by plants and release at end-of-life: see chapter 7.4.3.7.3. Indirect land use is an issue under consequential modelling and is in chapter 7.2.4.4. 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. 7.4.4.2 Modelling waste treatment (Refers to aspects of ISO 14044:2006 chapters 4.2.3.3.3) Overview This chapter focuses on modelling waste for deposition, the system boundary technosphere / ecosphere, and inventorying convention for waste flows. See also the specific provisions for modelling reuse, recycling and recovery under attributional modelling in annex 14.4 and consequential modelling in annex 14.5


See also the specific provisions for modelling reuse, recycling and recovery under attributional modelling in annex 14.4 and consequential modelling in annex 14.5. Complete modelling of waste management to elementary flows Waste flows (e.g. household waste, end-of-life products, wastewater from a process, tailings from ore processing, and the like) are no elementary flows but are flows inside the technosphere. Therefore their further management and treatment needs to be modelled until


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results the related elementary flows cross the system boundary. This is the same as for any other process in the system. Waste flows therefore shall not be left as such in the inventory, with one exception: for radioactive waste, so far no agreed modelling is available; radioactive waste flows are to remain in the inventory and are to be differentiated at least into highly, medium and low radioactive waste. If other waste flows are left in the inventory, this shall be clearly documented and the user be advised to complete the model. Otherwise the lack of accuracy and completeness shall be considered in the results interpretation. Frequent errors: Incomplete modelling of waste management In LCA practice it can still often be observed that relevant amounts of waste flows are kept in the inventory, i.e


Frequent errors: Incomplete modelling of waste management In LCA practice it can still often be observed that relevant amounts of waste flows are kept in the inventory, i.e. the LCI work and hence LCIA results are incomplete. That should be avoided or otherwise must be reported and explicitly considered in interpretation of results. Sometimes this is caused by an unclear/inappropriate definition of the system boundary between technosphere and ecosphere (see chapter 6.6). This results in errors such as e.g. inventorying tailings from ore processing as such instead of modelling the leaching of e.g. sulphuric acid and metals emissions from these tailings. A complete modelling of all relevant waste flows - e.g. using generic or sector-average waste management models - is a single means that can help substantially to complete existing inventory data


A complete modelling of all relevant waste flows - e.g. using generic or sector-average waste management models - is a single means that can help substantially to complete existing inventory data. Optionally, waste flows can additionally be kept in the inventory as “Reminder flows” that are clearly identified as not being part of the normal (i.e. impacting) inventory. Note that this option is only as additional information for reporting purposes as sometimes required by individual EPD systems, but is not substituting the complete modelling of waste management to the elementary flows. Inventorying convention for waste Modelling of waste treatment can be done in two ways:  either by inventorying it as a physical flow of waste in the output (i.e. in sense of the material flow direction, as for all material and god flows along the supply-chain),  or as service flow in the input (i.e. in sense of a purchased service, as incurred cost on the input side, the same as for other services)


in sense of a purchased service, as incurred cost on the input side, the same as for other services). It is recommended to model generated waste in the output of processes, as this results in less confusion especially when calculating process mass and element balances, but also already during modelling and depicting the systems flow chart, as well as in external communication. Littering / discarding to nature For littering of complex goods such as for example batteries, the emissions from the battery shall be modelled/estimated and inventoried as elementary flows. I.e. not the "battery" itself would be the emission flow but the emissions that effectively leave the battery to the surrounding soil, water and air. This is necessary as complex goods cannot be well captured with LCIA methods, but remain an inventory issue that needs specific modelling of the littering situation. Hence, although the littered goods ends up in the environment, it is modelled as part of the technosphere


Hence, although the littered goods ends up in the environment, it is modelled as part of the technosphere. In line with the definition of interventions, only single substances are the emission elementary flows that are inventoried. It is recommended to keep the information of the littered good in the inventory as reminder flow (see chapter 7.4.3.8). The modelled assumptions of the releases shall be documented.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results Preferably, the process of the behaviour of the littered good is modelled as separate unit process. An example is a physical effect that materials that may exert on wildlife e.g. if littered to rivers or the sea. In that case, the effect is to be inventoried in a respective elementary flow, as required by the applied LCIA method (next to e.g. emissions that may take place in addition). Provisions: 7.4.4.2 Modelling waste treatment I) SHALL - Waste and end-of-life product deposition: This shall be modelled as follows: [ISO!] I.a) Model waste management completely: Waste and waste water treatment shall be modelled consistently to the boundary between technosphere and ecosphere; otherwise this shall be clearly documented and be explicitly considered in later interpretation


This modelling includes all treatment steps up to and including disposal of any remaining waste to waste deposits or landfills and inventorying the emissions from these sites to/from the ecosphere. Two exceptions are radioactive wastes and wastes in underground deposits (e.g. mine filling), which should be kept as specific waste flows in the inventory, unless detailed, long-term management and related interventions have been entirely modelled also for these. I.b) Modelling discarding of goods into nature: For unmanaged landfilling, discharge, and littering (i.e. discarding goods individually into nature) the related individual interventions that enter the ecosphere shall be modelled as part of the LCI model. This also applies analogously to other interventions than emissions, if the used LCIA method covers such. The littered / landfilled good should be additionally inventoried as reminder flow


This also applies analogously to other interventions than emissions, if the used LCIA method covers such. The littered / landfilled good should be additionally inventoried as reminder flow. I.c) Modelling waste as output: Waste flows should be modelled following the material flow logic. That means inventorying the waste on the output side of those processes where it is generated (e.g. production waste or end-of-life product as output of the use stage). For waste management processes that means that the waste flows should accordingly be modelled on the input side if the process, with any potentially produced secondary goods and remaining wastes being on the output side. This eases mass and element balancing. For cost calculation purposes, the cost of the waste treatment service may be assigned to the waste flow as additional flow property. Note: The use of generic waste treatment models / processes may be considered to limit time and resources required for data collection


Note: The use of generic waste treatment models / processes may be considered to limit time and resources required for data collection. 7.4.5 Naming and other conventions (Refers to aspects of ISO 14044:2006 chapters 4.3.2.2 and 4.3.2.3) Equally common across attributional and consequential modelling are a number of conventions around nomenclature and other conventions. These identify and define the same commonly required objects (e.g. “Carbon dioxide” as “Emission to air”, “kg” as unit for the property “Mass”, etc.). This is a pre-requisite for being able to combine and integrate inventory data sets from different data developers to systems and LCA studies and to link LCIA methods correctly to


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results the resulting inventory results. Otherwise multiple occurrence of flows, incomplete impact assessment, and fundamental incompatibility of the inventories would be the consequence. These conventions also provide the basis for proper identification and naming of e.g. new elementary flows, including the need for CAS No and the like, their measurement in appropriate and compatible units and the like. While most elementary flows are reported in the flow property “mass” and expressed in measurement units such as “kg”, some elementary flows are to be reported as “lower calorific energy value” and expressed in the unit “MJ” (e.g. for energy resources), others as “ionising radiation activity” in the unit “kBq” (for emitted radioactive isotopes)


for energy resources), others as “ionising radiation activity” in the unit “kBq” (for emitted radioactive isotopes). Product and waste flows are measured in the individually identified, appropriate flow property and unit. The separate document “Nomenclature and other conventions” gives the detailed provisions on this. The set of ILCD reference elementary flows, flow properties and unit groups implement this nomenclature guidance document and provide a ready-made set of 19000+ elementary flows and the commonly required flow properties and unit groups. For more details on naming of flows and other conventions see the document on “Nomenclature and other conventions”161. Provisions: 7.4.5 Naming and other conventions I) SHALL - Elementary flows: [ISO+] I.a) Use ILCD reference elementary flows: The 19000+ pre-defined ILCD reference elementary flows, flow properties (named “properties” in ISO/TS 14048 and “quantities” in ISO 31) and unit groups shall be used per default, if available


I.b) Define new elementary flows consistently: New elementary flows shall be created meeting the methodological requirements of this document (see chapter 7.4.3). They shall per default be measured in flow properties (e.g. upper or lower calorific value) and units (e.g. MJ or kWh) applying the guidance given in the separate document “Nomenclature and other conventions”. Exceptions are only possible if a different unit (e.g. one year of production) is explicitly required for the intended applications; in that case the use of not ILCD-compliant units shall be brought to the awareness of the data set user. I.c) Use ILCD elementary flow categories: New elementary flows shall be classified in the elementary flow categories and sub-categories as defined in the guidance document “Nomenclature and other conventions” (e.g. “Emissions to fresh water”, “Resources from ground”, etc.). If required for the applied LCIA method (see chapter 6.7.5), differentiated compartments may be used


“Emissions to fresh water”, “Resources from ground”, etc.). If required for the applied LCIA method (see chapter 6.7.5), differentiated compartments may be used. II) SHOULD - Product and waste flows and processes: The naming and classification of product and waste flows as well as processes should apply the recommended nomenclature and they should be measured in the flow properties and units given in the guidance on “Nomenclature and other conventions”. [ISO+] III) SHALL - Flow properties and unit groups: The assignment and naming of new flow 161 The guidance foresees also, specifically for chemical substances (both inputs and emissions) the identification through CAS No. to avoid errors.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results properties and unit groups shall apply the recommended nomenclature given in the guidance on “Nomenclature and other conventions”. [ISO+] Note that the need to create new units is a rare exception for LCA practitioners; creating new flow properties will be seldom. For LCIA method developers the need to create new unit groups occurs frequently. 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. 7.5 Developing generic LCI data Overview In LCA, specific, average and generic data sets are often differentiated. In practice typically a combination is found


7.5 Developing generic LCI data Overview In LCA, specific, average and generic data sets are often differentiated. In practice typically a combination is found. The "pure" concepts are nevertheless explained here, as they imply relevant differences in data collection, modelling, documentation, and review. Terms and concepts: Specific, average and generic data sets Specific data A specific data set in its pure form represents a single process (e.g. a specific technology as operated on a given site) or system (e.g. a specific product model of a single brand) . It exclusively contains data that has been measured at the represented process. For data sets on whole systems that would means that all data for all processes has actually been measured. Average data An average data set ideally combines different specific data sets and/or other average data in an averaging way to represent a combination of processes (e.g. different waste incineration technologies) or systems (e.g


different waste incineration technologies) or systems (e.g. a products group). The averaging can - among others - go across technologies, products, sites, countries, and/or time. Generic data A generic data set has been developed using at least partly other information then those measured for the specific process. This other information can be stoichiometric or other calculation models, patents and other plans for processes or products, expert judgement etc. Generic processes can aim at representing a specific process or system or an average situation. Both specifically measured data and generic data can hence be used for the same purpose of representing specific or average processes or systems. A generic data set represents a typical variant of the process or system, an average data set represents the average situation for the process or system, in both cases within a specified geographic region and time


The difference lies in how the data set is modelled: in the first case the product and its life cycle is specified with typical (or representative) characteristics and the inventory is modelled accordingly. In the second case several products (or technologies or production plants) are separately modelled and the inventories are subsequently averaged. Collecting data for generic data sets For generic data sets, plan the data collection and system model based on knowledge about the typical or representative/average characteristics of the process or product. Typical characteristics are: the technology routes and raw material bases which are used, emission


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results abatement technologies and emission limits to be met, operation parameters, material composition, etc. Note that an averaging of process or product characteristics is not always useful (e.g. in case of averaging of two very different technologies that produce the same material) or may result in allocation problems (if one of the averaged processes is multifunctional). In those cases a combination of generic modelling and averaging should be foreseen. The generic data set can also reach a high quality IF the information and data for the typical characteristics of the system or technologies are available. The effort for modelling generic data sets is clearly smaller, but it has limited applications, basically its use as background data set, and – if high quality could be achieved – as benchmark


The effort for modelling generic data sets is clearly smaller, but it has limited applications, basically its use as background data set, and – if high quality could be achieved – as benchmark. Specific data has the clear advantage of representativeness compared to generic data. In practice specific data is however not always the most appropriate source for a required data set. This is e.g. if the available specific data has lower quality than generic data. Generally the aim should be to first look for available specific data or measure it and then go for generic approaches. 7.6 Selecting secondary LCI data sets (Refers to aspects of ISO 14044:2006 chapters 4.2.3.3.2) Overview Secondary data refers to data that is not based on measurements of the respective process(es) in the foreground system. I.e. if data for a missing foreground process is derived from patents this is secondary data, even if done by the process operator


I.e. if data for a missing foreground process is derived from patents this is secondary data, even if done by the process operator. Also all data that is obtained for use in background system is secondary data, even if provided by the suppliers162. For the background system, data from secondary data providers (especially generic or average process data sets) are provided in LCI databases of national or regional LCA projects, consultancies and research groups. One way to identify suitable data sets is the upcoming ILCD Data Network that allows all data providers to distribute their data sets, upon own conditions – as long as the data meets the minimum requirements of the ILCD Handbook or other, entry-level requirements that might be set. Frequent errors: Insufficient methodological consistency of background data When selecting secondary data sets, it is important is to ensure that all data sets used in the modelling of the system model are methodologically consistent


The use of inconsistent data can unfortunately often be observed in practice. This is done due to a lack of awareness of the problem, or ignoring it to save efforts or costs. However, the use of inconsistent data from different data systems makes the whole LCI/LCA study unreliable and distorted, often with wrong conclusion and recommendations drawn. The analysis of methodological consistency is hence one key issue to be covered by an independent external review process. The selection of secondary data (e.g. generic and average data for background use) has to consider their appropriateness and consistency in terms of methodology and regarding the data quality of the inventories, i.e. their representativeness, completeness, and precision. This is indispensible to ensure that together with the primary data they achieve the required completeness and precision of the system‟s LCI


their representativeness, completeness, and precision. This is indispensible to ensure that together with the primary data they achieve the required completeness and precision of the system‟s LCI. An appropriate documentation of these data 162 Note that the term secondary data provider usually refers to all other sources than the producing or service providing businesses and their trade associations. That can be e.g. consultants or research groups.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results sets, e.g. in the ILCD data format that has been developed for this purpose, substantially supports their correct selection and use, as well as supports interpretation of results. Pre-verified data The use of already independently reviewed generic background data sets (but also average data e.g. form trade associations) is recommended as it has two advantages: it gives an independent guarantee about the claimed quality of the data set. In addition, it considerably lowers the review effort, as the data set has already been reviewed and when using the data set only the appropriateness of the selected process for the analysed system is to be judged


Provisions: 7.6 Selecting secondary LCI data sets Note that these provisions also apply to the development of unit process and partly terminated system data sets as deliverables, as the cut-off rules need to be evaluated from the system's perspective. Attributional and consequential modelling and the Situations A, B and C need at least partially differently modelled data sets. I) SHALL - Use consistent secondary data sets: The secondary data (generic, average or specific data sets) to be used in the system model shall be methodologically sufficiently consistent among each other and with the primary data sets that were specifically collected. II) SHOULD - Quality-oriented selection of secondary data sets: Secondary data sets should be selected according to their data quality in a stricter sense, i.e. their technological, geographical and time-related representativeness, completeness and precision


their technological, geographical and time-related representativeness, completeness and precision. Their reference flow(s) and/or functional unit(s) should moreover be sufficiently representative for the specific processes, good or service that they are meant to represent in the analysed system. III) MAY - Prefer pre-verified data sets: It is recommended to give preference to already critically reviewed data sets ("pre-verified data") as this limits the effort for an review of the analysed system: only the appropriate use of these data sets in the analysed system needs to be reviewed. [ISO+] IV) MAY - Prefer well-documented data sets: It is recommended to give preference to data sets that are supported by a comprehensive and efficiently organised documentation. This allows the modeller (and later a reviewer) to judge the data set's quality and its appropriateness for the analysed system


This allows the modeller (and later a reviewer) to judge the data set's quality and its appropriateness for the analysed system. [ISO+] The combined use of data from different sources is facilitated by using either single operation unit process data set background systems that can be adjusted / re-modelled by the user to be consistent with the analysed system, or by using LCI results data sets that are consistent with the methodology applied in the analysed system. 7.7 Averaging LCI data Overview Figure 22 illustrates the main different forms of processes averaging (also named horizontal averaging) and systems averaging (also named vertical averaging): In process averaging, two or more processes that provide the same functions but represent different e.g. technologies, sites, years, etc. are averaged. This typically includes a weighing a non-


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results even of the inventories according to their contribution to the to-be-represented average situation. E.g. may the steel industry develop a global sector-average Blast Oven Furnace (BOF) process data set, by inventorying the BOF processes one by one at the individual sites and summing up the inventories, weighted / scaled by the relative contribution of each site to the total BOF steel output. In such averaging any missing data is typically filled with data from similar e.g. sites, to ensure that the e.g. technology and country mix represents well the aimed at average. Systems' averaging analogously averages the cradle-to-gate or cradle-to-grave inventories of two or more systems. E.g


technology and country mix represents well the aimed at average. Systems' averaging analogously averages the cradle-to-gate or cradle-to-grave inventories of two or more systems. E.g. expanding on the above example, could the cradleto-gate inventories of BOF steel of the various sites be summed up and averaged in a weighted way. This would include the background system of the BOF process, i.e. resulting in global average BOF steel as a product ("system"). Figure 22 Processes averaging ("horizontal averaging", top) and systems averaging ("vertical averaging", bottom); schematic. As initially mentioned, in practice often a combination of both specific and generic approaches will be found, as e.g. different production routes with different raw material bases cannot usefully be integrated into one "typical" process (or even full life cycle), so that the main variants are modelled as generic data sets and the inventories are subsequently averaged


A specific and often used type of average data sets are production, supply and especially consumption mix data sets; the latter is the most commonly required one in LCA. Figure 23 illustrates the concepts:  The production mix of a given product of Country A is the average of the inventories of the different technologies/routes that produce that product, weighted by output in that time period as operated in the territory of country A. The weights that should be used in LCA are the physical units of the product (e.g. mass, volume, pieces), not the production or market value.  The consumption mix is the inventory of the production mix plus the inventories of the imported products minus the inventory of the exported products. The composition and the amounts of the imports from the different countries is to be considered when averaging the data to the weighed consumption mix


The composition and the amounts of the imports from the different countries is to be considered when averaging the data to the weighed consumption mix. Note that other than exemplified in the figure, the export mix of a country often differs from its production mix and also among the target countries; it is to be analysed whether the differences are relevant for the analysed system and question. The same applies analogously of course for the import mix. Process A x% Process B y% Process C z% Average process 100% + +... + System A x% System B y% System C z% Average system 100% + +... +


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results The supply mix is then the production mix plus the import mix, i.e. the mix of what is available in the country for consumption. Figure 23 Illustration of the trade-relations between countries, as basis for calculating the production, consumption and supply mixes of products. Note that when calculating the mix of services of a country, care needs to be taken to avoid double-counting as imported services may be physically performed in the countries territory (e.g. on-site consulting services), while others are performed in the foreign country (e.g. tourism services to citizen of the analysed country). I.e. other than for goods, where the physical flow of the good goes from the source to the sink, for services the physical flow of e.g


tourism services to citizen of the analysed country). I.e. other than for goods, where the physical flow of the good goes from the source to the sink, for services the physical flow of e.g. staff performing the services in another country or tourists receiving the service in a another country makes this less clear. In general and for both goods and services, the direction of a product is opposite to the direction of the money flow. This helps identifying and calculating such trade-mixes. Collecting data for average LCI data sets When basing average data sets on the combination of producer specific data sets, plan the data collection to be based on information on e.g. the relative contribution of the individual producer or a certain production route to the overall production (see earlier examples on the average BOF process and BOF steel product data sets). This is necessary to be able to calculate a representatively weighted average data set


This is necessary to be able to calculate a representatively weighted average data set. In the frequent case, that data is not available for all production sites or service operators, other additional information is required, especially for which share of the market the available inventory data and the specific technologies, countries etc. is representative. The average data set is hence often more representative of the process or system than the generic data set. This is valid provided that sufficiently representative data is available for Country C Country A Country D Various oversea trade partner countries Import Export Export Import Country A production mix Country D production mix Legend:


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results all relevant product variants, sites, etc. and can be accompanied by statistical information of how much data varies between the underlying products or sites. The effort for data collection is clearly higher for average data sets than for generic data sets, but this approach offers in return other advantages such as the possibility of internal benchmarking, weak point / improvement analysis, generation of producer-specific EPDs etc., i.e. the intended applications largely determine which variant is preferable. 7.8 Modelling the system (Refers to aspects of ISO 14044:2006 chapter 4.3.2) Introduction and overview The system is to be modelled applying the LCI modelling framework that was identified in chapter 6.5.4 as part of the scope definition and in accordance with the goal of the LCI/LCA study


This has two interrelated aspects: how to actually model the system along the used LCI modelling framework. This is addressed in this chapter. Regarding overarching methodological issues see chapters 7.4.3 and 7.4.4. As the second and more complicated issue, multifunctionality of processes has to be solved, i.e. allocation criteria are to be identified and applied (for attributional modelling) or superseded processes to be used in case of substitution are to be identified (in case of consequential modelling). The issue of solving multifunctionality for attributional modelling is given in the next subchapter. The guidance on identifying superseded processes for consequential modelling has already been addressed in chapter 7.2.4.6, as it belongs to that earlier step of identifying processes within the system boundaries


Filling initial data gaps For a cradle-to-gate or cradle-to-grave system, in principle the same interim quality control criteria apply as for the unit process (see chapters 7.4.2.11 and 9.3.2 for the systematic approach). It additionally plays a role which amount of the specific unit processes is required in context of the whole product system: for those parts of the product system that contribute little to the final results (i.e. to the overall environmental impacts of the product), the cut-off criteria can be less strict, while still achieving the overall requirements to completeness and precision. E.g. if a laptop is analysed over its life cycle, the PVC used for insulation of the internal wiring may contribute little and "data estimate" quality data may be sufficient. Whereas the electricity consumption in the use stage might be found to contribute e.g


Whereas the electricity consumption in the use stage might be found to contribute e.g. to 50 % or more to the overall environmental impact and its production must hence be included with high quality data to achieve a high accuracy and precision for the whole data set. For filling data gaps, estimate data sets may be considered to be used. Such may be e.g.:  generic or average data for missing specific data,  average data of a group of similar products for missing inventory data for other, not yet analysed products of that group,  correlation with other, more complete and high quality data for the same or similar process but from other data sources (e.g. industry average data for improving a producer-specific process),  justified judgements of technical experts / process operators.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results Relevant data gaps generally shall be filled with 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. Only data estimates 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 sets quality level shall be at least equivalent to a "Data estimate" (see annex). Scaling all processes of the system Modelling the system means to correctly scale the inventories of all processes that are included in the system boundaries of the analysed system


Scaling all processes of the system Modelling the system means to correctly scale the inventories of all processes that are included in the system boundaries of the analysed system. In practice that means to ensure that all product and waste flows that connect the foreground system with the background system are “saturated” with the appropriate background processes163. If the inventories of all required processes have been collected or compiled from data providers, this step is rather straightforward. Two main approaches exist in the widely used LCA software tools:  In the “process-flow” approach the modelling is done by manually or semi-automatically connecting processes via their input and output product and waste flows.  In the “matrix”-approach this connection is done automatically, provided all to-beconnected product and waste flows on the output and input side of all processes are identically named


 In the “matrix”-approach this connection is done automatically, provided all to-beconnected product and waste flows on the output and input side of all processes are identically named. In practice very often not exactly the required process data set is available, but data sets of similar products (e.g. “Carbon steel billet 9SMn28” instead of “Carbon steel billet 9SMn36”) or similar regions (“NL – Ammonia; technical, liquid” instead of “BE – Ammonia; technical, liquid”) are to be used. In “matrix” tools such cases need additional mechanisms and/or manual renaming or duplicating of processes as workaround to ensure a correct modelling. In “process-chain” tools such processes need manual connection of these product or waste flows. For details refer to your LCA software manual


In “process-chain” tools such processes need manual connection of these product or waste flows. For details refer to your LCA software manual. Additional quality control While formally a step done when collecting data or compiling data from background databases of data providers, in practice the modelling of the system is the moment when the LCI modeller is again to check the appropriateness of the used background processes. This is done along the data set documentation, especially regarding the data sets‟ technological, geographical and temporal representativeness as well as methodological appropriateness and consistency. The overall completeness and accuracy of the system model results is checked later along the calculated LCI results (see chapter 7.10) and controlled in view of the system boundaries as defined in chapter 6.6, leaving no quantitatively relevant unconnected product and waste flows in the inventory. Parameter settings Whenever parameterised processes are used (e.g


Parameter settings Whenever parameterised processes are used (e.g. for transport, waste management, but also for mixer-processes that mix different processes to represent a market mix or technology mix), the case-specific correct parameter values have to be set for all these processes. 163 This applies independently whether working for the background system with LCI results or with unit processes, as in practice the practitioner will embed the specific foreground system of the analysed product system into a background system (database).


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: 7.8 Modelling the system Applicable to Situation A, B, and C, differentiated. Differentiated for attributional and consequential modelling. Applies also to the development of unit process and partly terminated system data sets as deliverables, but only to quantify the achieved completeness and precision, as they need to be evaluated from the system's perspective. I) SHALL - Scale inventories correctly: The inventories of all processes within the system boundary shall be correctly scaled to each other and to the functional unit(s) and/or reference flow(s) of the analysed system164


II) SHALL - Complete system model: No quantitatively relevant product or waste flows shall be left unmodelled / unconnected, with exception of the reference flow(s) that quantitatively represent(s) the system's functional unit (additional provisions on waste flows see 7.4.4.2). Otherwise these flows shall be clearly documented and the resulting lack of accuracy and completeness be considered in the interpretation of results. [ISO!] Note that for unit processes all and for partly terminated systems selected inventories of the corresponding products and/or wastes modelling processes are intentionally left out of the system boundary. Their systems are nevertheless completed, while only for applying the cut-off rules. III) SHALL - Set parameter values: Set the parameter values to the required values in all used parameterised process data sets, if any


III) SHALL - Set parameter values: Set the parameter values to the required values in all used parameterised process data sets, if any. [ISO+] IV) MAY - Perform another round of interim quality control: It is recommended to precheck during modelling whether the data set or system is properly modelled and meets the quality requirements as identified/fine-tuned in the scope phase; the provisions for interim quality control of unit processes apply analogously (see chapter 7.4.2.11). For filling initial data gaps of included processes and systems estimate data sets may be considered to be used. Such may be e.g.: [ISO+] IV.a) generic or average data sets for missing specific processes / systems, IV.b) average data sets of a group of similar processes or systems (e.g


Such may be e.g.: [ISO+] IV.a) generic or average data sets for missing specific processes / systems, IV.b) average data sets of a group of similar processes or systems (e.g. products) for missing processes / systems for other, not yet analysed processes or systems of that group, IV.c) correlation with other, more complete and high quality process data sets for the same or similar process but from other data sources (e.g. industry average data for improving a producer-specific process). V) SHALL - Use consistent data to fill data gaps: Data gaps shall be filled methodologically consistent data sets, while 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


[ISO!] VI) SHALL - Use sufficiently quality LCI data sets top fill gaps: Only data and data sets 164 This can be visualised by having all processes connected with each other via their reference flows of interim products and wastes, in the correct amounts. Starting from central process and the amount(s) of the system's functional unit(s) or reference flow(s), all other processes are stepwise, relatively scaled. LCA software with graphical modelling interface shows the system in this way and/or the user is modelling the system explicitly by connecting the processes on that interface. Depending on the modelling approach implemented in the software, other mechanisms can be found that serve the same scaling purpose.


ILCD Handbook: General guide for Life Cycle Assessment - Detailed guidance First edition 7 Life Cycle Inventory analysis - collecting data, modelling the system, calculating results 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 or data set's quality shall be equivalent to at least the "Data estimate" quality level. See also chapter 7.4.2.11.3 and annex 12.3. Remaining data gaps shall be reported. [ISO!] Note that both the approach(es) used to fill initial data gaps and the resulting lack of representativeness, precision and methodological consistency of the whole data set is later to be clearly documented and explicitly considered when declaring the achieved data set quality or when drawing conclusions or recommendations from an LCA study. Note that the final check on the achieved overall environmental completeness / cut-off is detailed in chapter 9.3.2


Note that the final check on the achieved overall environmental completeness / cut-off is detailed in chapter 9.3.2. Note that decisions on any omissions of life cycle stages, types of activities, individual processes or elementary flows must be clearly reported and should be justified by the fact that they do not contribute significantly to the LCI results in view of the intended application(s) of the outcome of the LCI/LCA study. Otherwise they need to be reported and considered when declaring the achieved data set quality and/ drawing conclusions and recommendations from the study


Otherwise they need to be reported and considered when declaring the achieved data set quality and/ drawing conclusions and recommendations from the study. 7.9 Solving multifunctionality of processes in attributional modelling (Refers to ISO 14044:2006 chapter 4.3.4) 7.9.1 Introduction and overview (Refers to aspects of ISO 14044:2006 chapter 4.3.4.1) The problem of multifunctionality (For an overview of multifunctionality and the different approaches of how to solve it see also chapter 6.5.3.) Many processes contribute to the provision of more than one function by yielding more than one product (co-products, i.e. co-goods and co-services) or by servicing more than one input (e.g. waste treatment of mixed waste flows), or combinations thereof. The problem about such multifunctional processes is that in LCA we need to analyse a single system in order to determine the specific environmental impact which can be related to its life cycle


The problem about such multifunctional processes is that in LCA we need to analyse a single system in order to determine the specific environmental impact which can be related to its life cycle. In the real world there is however hardly any system which exists in isolation. As soon as a co-product arises in a process that is part of the system being analyzed, it is used typically in a different system. This means that the process becomes part of another system as well165, and that its environmental impacts can no longer be fully ascribed to the system that we study. An apparently different but methodologically fully analogous situation of shared impacts is associated with the recycling of end-of-life of products and of waste occurring during production or use: a material may be recycled, energy be recovered, or part be reused from one system and used again in one or more other systems