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Tag: Related study phase: Goal and scope definition

G-16 (Buildings) / G-15 (Products) Accounting for carbon storage/carbon sequestration

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Aspect G-16 (Buildings) / G-15 (Products) Accounting for carbon storage/carbon sequestration
Description
 Some products (e.g. wooden products) take up atmospheric carbon dioxide while producing biomass. Concrete- and lime-based products can also take up atmospheric carbon dioxide through recarbonization during the use phase . By using these materials or products, this fixed CO2 is stored during the service life of the product. It is then released during combustion processes, or in landfill during full or partial decay of the biomass, as either CO2 or methane, which itself may be captured to produce CO2. Owing to the storage of carbon of biogenic origin in some products during the use of these materials, the CO2 stored is not released in today’s ecosphere but at some future date. Usually, 100-year assessment periods for the fate of greenhouse gases are taken into account in LCA studies (use of the indicator global warming potential, GWP100), but, depending on the case, this period can be insufficient to counteract the storage period.In this case, how should the biogenic carbon be taken into account? Should this temporary storage effect be accounted for? Also, the matter of sequestration of carbon in soils and organic matter due to land-use changes is frequently discussed. How should this aspect be treated?

related study objective

 ☒ stand-alone LCA ☒ comparative assertion

related study phase

 ☒ ☐ ☐ ☐ ☐
goal and scope definition inventory analysis (LCI) impact assessment (LCIA) interpretation reporting

relevant for
new buildings existing buildings building products screening LCA simplified LCA complete LCA
Provisions As a conservative approach, the storage or sequestration of biogenic carbon as an additional benefit should not be accounted for, as this is a temporary effect. All greenhouse-gas-related environmental impacts should be quantified solely with the use of IPCC’s GWP-100 impact category. This means that the uptake of carbon dioxide into biomass is considered in the inputs to biomass production, and the emissions of biogenic carbon (as carbon dioxide or methane) are considered in the outputs.
Rules from

ILCD

 

 Provisions 7.4.3.7 Future processes and elementary flows
Citation from provisions 7.4.3.7:
“VII) SHALL – Inventory temporary carbon storage and delayed GHG emissions: only if temporary carbon storage in bio-based goods is considered […] delayed emission as CO2 or CH4 shall be modelled analogously to delayed emissions of fossil carbon dioxide and other greenhouse gases” Additional citation from the ILCD Handbook:The uptake of “carbon dioxide” by plants shall be inventoried under “resources from air”. This applies to all photosynthetic organisms.

The ILCD Handbook recommends that for better methodological clarity and flexibility, as well as easier communication, the release of carbon dioxide and methane be additionally differentiated between fossil and biological sources. Both the uptake of carbon dioxide from the atmosphere and the release of both fossil and biogenic carbon dioxide are assigned characterization factors for the impact assessment. The full provision for inventory of temporary carbon storage and delayed GHG emissions can be found in the ILCD Handbook.
Guidance
 This aspect is under intense discussion within various organizations. Different perceptions exist, and various documents propose different solutions to this question. For example, some documents define ‘discounts’ for the temporal storage of carbon in products. Others suggest, for example, reduction factors to be applied to GWP results for a temporal sequestration of carbon in soil and organic matter due to land-use change.In order to be flexible concerning future development of and consensus-building on this aspect, it is helpful to track carbon with a distinction made between biogenic and fossil sources. For example, in the background LCI databases, it is likely that elementary flows will be found such as:Resources: ‘carbon dioxide (resource), in air’Air emissions: ‘carbon dioxide (fossil), in air’ and‘carbon dioxide (biogenic), in air’.This is also valid for methane and carbon monoxide.Further information can be found in the following sources:

  • ISO working group on carbon footprint;
  • PAS 2050.
  • Standard in preparation in CEN TC 175 prEN 16449: ‘Wood and wood-based products – Calculation of sequestration of atmospheric carbon dioxide’ (status: under approval)

The treatment of biomass at the end of life is covered in the aspects of Module C and this should be considered alongside this guidance.

G-17 Differences in background data system boundaries

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Aspect G-17 Differences in background data system boundaries
Description
 Currently, practitioners have to deal with various different data sources, such as public or commercial LCI databases, EPDs, literature, etc. All these data have been calculated by applying different rules, and so special attention has to be paid to assessing the consistency of these different sources. An increasing number of EPDs for building products are freely available in the market. These EPDs have been produced in the framework of different programmes, applying different product category rules (PCR) and system boundaries, and so they should not be directly compared nor combined. Recently, the EN 15804 standard has been approved, and in the coming years will foster harmonization between the various EPD programmes. In the meantime, how can the practitioner deal with differing background data?

related study objective

 ☒ stand-alone LCA ☒ comparative assertion

related study phase

 ☒ ☐ ☐ ☐ ☐
goal and scope definition inventory analysis (LCI) impact assessment (LCIA) interpretation reporting

relevant for
new buildings existing buildings construction products screening LCA simplified LCA complete LCA
Provisions An increasing number of EPDs for building products are available. These EPDs apply different system boundaries, e.g. cradle to gate (product stage), cradle to grave (the whole life cycle) and cradle to gate with options (Modules A1–A3 plus other, additional modules). If the EPD is EN 15804 compliant, then the information is declared separately for each module, facilitating its use in building LCA studies. EPDs that comply with EN 15804 should also provide additional technical information to ensure proper understanding of a product’s function in a building by supporting scenario development at the building level.For all these reasons, EN 15804-compliant EPDs can be accepted as a data source for building LCA as well as generic data (if the goal is to do e.g. a screening LCA). These EPD data may also be seen as an appropriate data source for background data as well as the usual generic data.
Rules from:
 EN 15804
5.2 Types of EPD with respect to life cycle stages coveredEN 15978
10 Selection of environmental data and other information – Use of Environmental Product Declaration(s)
Guidance
 Different EPDs and other background data may be used for a building LCA study; however, special care has to be taken when using these different data sources for building LCA. In this sense, it is key to have a good understanding of whether the LCA-based information found in an EPD represents the product stage only (e.g. cradle to gate), the product stage and selected further life cycle stages (cradle to gate with options EPD) or the complete life cycle of the product (cradle to grave). Additional technical information included in the product’s EPD (such as service life, transportation distance, loss of the product on-site, etc.) would also be very useful for the assessment at the building level. In any case, consistency of the LCA modelling should be ensured so that the system boundary of the EPDs is homogeneous.Whenever possible, the use of EPDs that comply with EN 15804 should prevail, if they are more relevant for use in a national context than any other background data. In addition, the practitioner should check that the LCA-based information found in such EPDs is compatible with the scope of the study.In addition to such EN 15804-compliant EPDs, the practitioner most likely has to rely on various background data sources, such as public or commercial databases. It is strongly recommended that practitioners use as much data as possible from a consistent source (e.g. one public national database), which ideally should be methodologically consistent with the appropriate EPDs (e.g. from one national EPD programme with the same methodological assumptions). If EPD data are to be used as background data, it is important to ensure that they can be reused for further EPD – e.g. a raw material EPD used for a product EPD. In this context, it is important to have a data-compatible exchange format to ease the use of EPD (the information to be reused is likely to be only the cumulative impact results, as no LCI is provided in most EPD programmes).

G- 18 Allocation case for cement-based materials

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Aspect G- 18 Allocation case for cement-based materials
Description
 Increasing numbers of building products are being made of secondary raw materials (SRM), or of generated waste that can be recycled throughout their life cycle. On the one hand, recycling eliminates the need to use virgin raw materials. On the other hand, the new commercial interest in waste can be seen as a shift in their status from waste to co-product.Several industries use a considerable amount of waste produced in other economic sectors (e.g. the cement industry uses blast furnace slag from the steel industry, and fly ash from electricity production). Depending on the ‘end of waste‘ status of each product, allocation rules may be needed to separate the burdens between the producer of the waste and the user. The environmental impact of very common building materials can thus vary greatly, depending on the allocation rules chosen. How can this critical allocation case be treated, e.g. for the use of waste in the cement and concrete materials?

related study objective

 ☒ stand-alone LCA ☒ comparative assertion

related study phase

 ☒ ☐ ☐ ☐ ☐
goal and scope definition inventory analysis (LCI) impact assessment (LCIA) interpretation reporting

relevant for
new buildings existing buildings construction products screening LCA simplified LCA complete LCA
Provisions The allocation rules should comply with EN 15804 and EN 15978. In addition, the rules of national EPD programmes should be followed (if available).
Rules from:

EN 15804

 6.4.3.2. Co-product allocation

ILCD

 14.4.1.2 Market value of waste/end-of-life product is above zero, i.e. it is a co-product14.4.1.3 Market value of waste/end-of-life product is negative
Guidance
 Generally speaking, the allocation rules should be defined in every national context, together with the relevant sectors that use and produce the waste or co-product).A manufacturer of building products using e.g. wastes from another economic sector needs to share burdens with the first user. The allocation actually depends on the ‘end-of-waste’ status: that is, whether the waste is treated as waste (treatment allocated to the first user, and reported in Module C) or whether it is treated as a new product (when end-of-waste status is reached, the waste is transformed into a product, and the processing is allocated to the new product life cycle).

One option is to look at the market value of the waste, as proposed in the ILCD Handbook (see reference above). For example, waste from the steel industry (blast furnace slag) or from electricity production (e.g. fly ash) may be used to produce cement with a low clinker content.

Current practice in Europe shows varying rules for the allocation of cement SRM. They are treated as co-products in the UK (and in the subsequent EPDs), whereas they are considered as waste in France and in Germany (and in the subsequent EPDs of these two countries). The new European Waste Directive (see below) is currently not being applied in a consistent way.

The practitioner, when using LCA data that may be sensitive to the allocation of by-products according to the EU Directive (considered either as waste or as co-product), should specify the allocation rules, especially for complete LCA. Sensitivity analysis should be conducted if the allocation of by-products has a significant role in the LCA results.

A third guidance point concerns the use of background data. Depending on the type of background data, they may not comply with the allocation rules. As the practitioner does not have an influence on the background data, the best recommendation is to be transparent, e.g. in the LCA methodological report.

Further information and references on this issue:

G-18 (Buildings) / G-16 (Products) Allocation

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Aspect G-18 (Buildings) / G-16 (Products) Allocation
Description
 Normally, LCA studies should focus only on a single product at a time. However, systems under assessment often produce more than one product. The same problem arises when different waste flows are treated collectively in the same process (e.g. incineration). In these situations, the allocation problem arises: that is, how to allocate the environmental loads of those shared processes to the products delivered. In the building sector, owing to its long supply chain and influence, virtually all allocation cases can be found, from raw materials supply and manufacture (e.g. co-production processes) to the end of life (e.g. energy recovery during the incineration of building products) but also during the use phase (e.g. allocation of renewable energy produced in the building) The allocation rules may have a significant influence on the LCA results, and so this is a key methodological aspect. How should allocation be tackled in the case of buildings and building products?

related study objective

 ☒ stand-alone LCA ☒ comparative assertion

related study phase

 ☒ ☒ ☐ ☐ ☐
goal and scope definition inventory analysis (LCI) impact assessment (LCIA) interpretation reporting

relevant for
existing buildings new buildings building products screening LCA simplified LCA complete LCA
Provisions According to ISO 14040/14044, the ILCD Handbook and the EN 15804/EN 15978 standards, when dealing with systems involving multiple products and recycling processes, allocation should be avoided as far as possible; when unavoidable, allocation should be considered carefully, and justified. Allocation should be handled as mentioned in EN 15804/EN 15978 and the ILCD Handbook. Other aspects provide guidance for the most frequently found allocation problems occurring for energy-efficient buildings or products.
Rules from:

EN 15804

 6.4.3 Allocation of input flows and output emissions
6.4.3.1 General
6.4.3.2 Co-product allocation
6.4.3.3 Allocation procedure of reuse, recycling and recovery

ILCD

 Provisions: 7.9.2 Avoiding allocation by subdivision or virtual subdivision

  • “I) SHALL – Analyse whether allocation can theoretically be avoided by substitution
  • II) SHALL – Aim at avoiding allocation by subdivision or virtual subdivision”

Provisions: 7.9.3 Solving multifunctionality by allocation

  • “I) SHALL – Share inventory between co-functions by allocation
  • II) SHALL – Differentiate multifunctional processes and multifunctional products
  • III) SHALL – Two-step procedure for multifunctional processes
    • III.a) First step and criterion “determining physical causality”
    • III.b) First step and criterion “determining physical causality”
    • III.c) Checklist for “determining physical causality” criteria
  • IV) SHOULD – Second step and criterion “market price”
  • V) SHOULD – Two-step procedure for multifunctional products
  • VI) SHALL – Attributional modelling of reuse, recycling, recovery
  • VII) SHALL – System-wide consistent application of allocation
  • VIII) SHALL – 100% rules”
Guidance

The following main allocation methods are frequently used in LCA practice:

  • allocation based on market price (e.g. a gold mine where other precious metals such as silver are also extracted as co-products);
  • allocation based on physical mass/volume/energy content;
  • allocation based on exergy (e.g. a refinery with a multitude of products with high energy value).

The mass allocation may be preferred, as it is less sensitive to market price changes. However, there are no globally uniform rules. For complete LCA, an in-depth analysis has to be made of this issue, and the allocation procedure applied has to be justified. This is also the case for a study with a special focus on a certain aspect (e.g. recycling).

The ILCD Handbook (see rules above) provides a comprehensive procedure for doing the allocation in a consistent way. The practitioner should make sure that allocation rules are applied in a consistent way throughout the assessed system.

For building LCA applications, this means that the data used for the study should have been modelled using the same allocation rules. For example, if the blast furnace slag is considered as a co-product when it leaves the system boundary of a construction steel product, then the cement should use the slag as a co-product linked to the fabrication of slag in the steel industry. The same rules apply if the slag is not allocated as co-products; then the cement should use it as a waste. If the allocation rules differ between the steel and the cement then the system is not balanced, which does not comply with the ILCD rules. Further information on this relevant example for the construction sector can be found in the corresponding aspect.

The practitioner should also check that the sum of inventories allocated to all the co-products is equal to the inventory of the system before allocation was done [ILCD 2011a].

In addition, the LCA practitioner should prove that the chosen allocation rule does not change the overall conclusions and results of the study. This can be applied by scenario analysis (see the corresponding aspect), if allocation is used in foreground systems. Scenario analyses are most likely not feasible for assessing the impacts of the allocation rules used within background datasets.

G-19 Allocation examples for wooden products

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Aspect G-19 Allocation examples for wooden products
Description
 Increasing numbers of building products are being made of secondary raw materials (SRM), or of generated waste that can be recycled throughout their life cycle. On the one hand, recycling eliminates the need to use virgin raw materials. On the other hand, the new commercial interest in waste can be seen as a shift in their status from waste to co-product [Chen 2009].SRM are generally purchased between industrial sectors. There is then an allocation issue to share the burdens of the primary production process.The question to answer is: which allocation procedure should be chosen to allocate the impacts between the industry generating the waste or co-product and the industry that reuses it (e.g. in the case of wooden products)?

related study objective

 ☒ stand-alone LCA ☒ comparative assertion

related study phase

 ☒ ☐ ☐ ☐ ☐
goal and scope definition inventory analysis (LCI) impact assessment (LCIA) interpretation reporting

relevant for
new buildings existing buildings construction products screening LCA simplified LCA complete LCA
Provisions The allocation rules should comply with EN 15804 and EN 15978. In addition, the rules of national EPD programmes should be followed (if available).
Rules from:

EN 15804

 6.4.3.2. Co-product allocation

ILCD

 

 7.9.3 Solving multifunctionality by allocation
14.4.1.2 Market value of waste/end-of-life product is above zero, i.e. it is a co-product
14.4.1.3 Market value of waste/end-of-life product is negative
Guidance

Generally speaking, the allocation rules may be defined in each national context, together with the relevant sectors that use and produce the waste or co-product).

For example, a manufacturer of building products sending .g. wooden wastes to a recycling process needs to share burdens with the next user of the waste. The allocation depends on the end-of-waste status – that is, whether those wood wastes are treated as waste (treatment allocated to the product, and reported in Module C), or whether they are treated as a new product (when the end-of-waste status is reached, the wood wastes are transformed into a product, and the processing is allocated to the next user).

One option is to look at the market value of the waste, as proposed in the ILCD Handbook (see reference above). For example, wooden waste may be reused to produce particle board. This may have an economic value that is very different from that of the main product. (“A difference of more than 25% is regarded as high,” as stated in EN 15804.) In this case, the allocation rule should be based on an economic basis. The output is a co-product, and is not waste any more (the end-of-waste status has been reached).

In addition, in EN 15804 and EN 15978, the product can be considered as a co-product or as a waste depending on the life cycle stage considered. In the above example, an economic allocation may be applied for the wooden wastes during the production stage (Module A), whereas they will be considered as waste at the end of life (Module C).

However, comparison of the impacts of both the manufacturing plant and the building end-of-life activities shows that an economic allocation for wooden wastes in Module C would be very close to a ‘no allocation’ procedure – i.e. a waste status. Indeed, the impact of the EoL process can be assumed to be negligible when compared with the production process for energy-related impacts for example.

A third guidance point concerns the use of background data. Depending on the type of background data, they may not comply with the allocation rules. As the practitioner does not have an influence on the background data, the best recommendation is to be transparent, e.g. in the LCA methodological report.

Further information and references on this issue:

 

G-19 Allocation case: production of renewable energy on-site

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Aspect G-19 Allocation case: production of renewable energy on-site
Description
  The production of on-site renewable energy can occur at different time of the day, month and year, and may or may not meet on-site needs. Renewable energy may be consumed on site, or may be exported to the electricity grid or to a heating network, for example, according to the instantaneous needs of the building.How should this on-site energy production be accounted for, and can the loads and benefits be allocated between the electricity grid and the building?

related study objective

 ☒ stand-alone LCA ☒ comparative assertion

related study phase

 ☒ ☒ ☐ ☐ ☐
goal and scope definition inventory analysis (LCI) impact assessment (LCIA) interpretation reporting

relevant for
new buildings existing buildings construction products screening LCA simplified LCA complete LCA
Provisions
The amount of renewable energy produced with the help of on-site systems to supply operational energy for the use of the building should be accounted for as part of the LCI of the building being assessed, attributing the on-site production to the building life cycle.The allocation of exported energy follows the case studies of EN 15978, Annex B.
Rules from:
 EN 15978
7.4.4.7 Boundary for the operational energy use (Module B6)Annex B (informative) Exported energy – Case studies

ILCD
Provisions: 7.9.3 Solving multifunctionality by allocation
Provisions: 7.9.2 Avoiding allocation by subdivision or virtual subdivision
Guidance
 The method for the calculation of on-site renewable energy production should be consistent with [EN 15643-1]. Renewable energy produced by systems located on the building site and supplying energy demand for building uses should be considered (e.g. thermal solar panels, photovoltaic panels, wind turbines…). Other thermal energy gain from on-site renewable energy sources (solar gains through windows or solar walls) can be also accounted for complete LCA. Calculation method should be reported and justified.Boundary for energy production at operational stage should be consistent with boundary for product (A1–A3) and construction processes (A4–A5) modules:

  • If the energy produced by the on-site system is accounted for in Module B6, the production system should be accounted for in Modules A1–A5.
  • The accounting of renewable primary energy for the operational stage should be consistent with the accounting of renewable primary energy for materials, the amount of renewable primary energy is the measured output energy, not the amount of energy potentially available.

For on-site systems exporting energy outside the building boundary see the aspect described in Module B6: “Operational energy calculation – Allocation of energy production for on-site systems connected to grid”.

G-20 Define reference building

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Aspect G-20 Define reference building
Description
 The whole-life performance of nearly all building products can be assessed only in the context of a specific building. Is it possible to set a reference building for this comparison?

related study objective

 ☒ stand-alone LCA ☒ comparative assertion

related study phase

 ☒ ☐ ☐ ☐ ☐
goal and scope definition inventory analysis (LCI) impact assessment (LCIA) interpretation reporting

relevant for
new buildings existing buildings construction products screening LCA simplified LCA complete LCA
Provisions No definition of a general reference building is given, as such a building would not be applicable for all of Europe.
Guidance
 Definition of a reference building may be a feasible way to assess specific products within the context of their particular use. Currently, reference buildings have to be defined individually for each study. Further research may yield a generic European reference building, or perhaps national reference buildings. In defining a study-specific reference building, attention should be paid to the product use that is being assessed. The product, or the compared products, should provide functions relevant to the reference building, in order to assess the product adequately. For the assessment of products with energy-related functions, the LCA practitioner may explore whether national EPBD-related reference buildings exist, and whether they could be of use.

G-20 (Buildings) / G-17 (Products) Allocation case: reuse, recycling and recovery

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Aspect G-20 (Buildings) / G-17 (Products) Allocation case: reuse, recycling and recovery
Description
 When the lifespan of a product ends, it can be reused, recycled, or used for recovery in another product system. These recovery operations entail a benefit for the system that yielded them. How to allocate these benefits to the system under study, or to other product systems that will recover these materials, is still an open topic within the LCA community.What allocation method should be used for the reuse, recycling and recovery of construction waste?

related study objective

 ☒ stand-alone LCA ☒ comparative assertion

related study phase

 ☒ ☒ ☐ ☐ ☐
goal and scope definition inventory analysis (LCI) impact assessment (LCIA) interpretation reporting

relevant for
new buildings existing buildings building products screening LCA simplified LCA complete LCA
Provisions According to EN 15804, components for reuse and materials for recycling and energy recovery are considered as potential resources for future use. The reuse, recycling and recovery operations result in benefits, but also entail environmental loads. In the case of EPDs (products), the net environmental impacts (positive or negative) should be quantified separately in a so-called ‘Module D’. Calculation of Module D impacts should be based on average existing technology, current practice, and the net impacts of the recovery processes in comparison with the impacts of producing the substituted good (energy or primary raw material). EN 15804 provides guidelines for allocation with regard to reuse, recycling and recovery.EN 15978 refers to EN 15804 to deal with scenarios for reuse, recovery and recycling potentials outside the system boundary of the building under assessment, in order to describe the processes that lead to future substitution of resources.
Rules from:
 EN 15804
6.4.3 Allocation of input flows and output emissions
6.4.3.1 General
6.4.3.2 Co-product allocation
6.4.3.3 Allocation procedure of reuse, recycling and recoveryILCD
7.8 Modelling the system
Provisions: 7.9.2 Avoiding allocation by subdivision or virtual subdivision
Provisions: 7.9.3 Solving multifunctionality by allocation
“VI) SHALL – Attributional modelling of reuse, recycling, recovery
VI.a) Follow general rules for multifunctionality, observing specific aspects
VI.a.i) Dealing with waste and end-of-life products of negative market value that generate secondary goods
VI.a.ii) True joint process to be identified
VI.b) Provisions:
VI.b.i) Negative market value
VI.b.i) Market value equal or above zero”

14 ANNEX C: Modelling reuse, recycling, and energy recovery
Guidance
 Allocation can have significant effects on the results of an LCA study. Therefore the allocation method should be documented as transparently as possible, with reference, if possible, to the European standards or the ILCD Handbook. The aspect ‘Allocation example for wooden products’ provides further guidance. A recent article presenting the concept of Module D was presented at the 20120 Symposium on LCA and Construction. For deeper insight into this subject, the interested practitioner may refer to this article: [Leroy 2012].

G-22 Data selection for a product LCA

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Aspect G-22 Data selection for a product LCA
Description
 Various data sources exist for the calculation of product LCA data. They differ for example in terms of specificity, age, completeness and certainty. What data requirements apply for the production of product LCA data?

related study objective

 ☒ stand-alone LCA ☒ comparative assertion

related study phase

 ☒ ☐ ☐ ☐ ☐
goal and scope definition inventory analysis (LCI) impact assessment (LCIA) interpretation reporting

relevant for
new buildings existing buildings construction products screening LCA simplified LCA complete LCA
Provisions In general, specifications are given with regard to EPD: see 6.3.7 ‘Quality requirements’ in EN 15804. National EPD programmes that apply to the context of the LCA study may give more specific guidance.
Rules from:

EN 15978

 6.3.6 Selection of data
6.3.7 Data quality requirements

CEN/TR 15941

 Sustainability of construction works — Environmental product declarations — Methodology for selection and use of generic data

ILCD

  

ISO 14044

 4.2.3.6 Data quality requirements
Guidance
 Specific data are data relating to the specific process being studied.  Generic data are more general data – they may for example be an average from a trade association, a specific dataset that is used as a proxy for typical production, or a dataset developed from literature sources. Data quality considers the relevance and quality of the dataset relative to the process being considered, taking account of

a)    age of data;

b)   geography;

c)    technology;

d)    precision;

e)    completeness;

f)     representativeness;

g)    consistency;

h)    reproducibility;

i)     sources of the data;

j)     uncertainty.

For screening and simplified LCA, it can be appropriate to use lower data quality requirements: for example, a single database for upstream and downstream data may be used without considering further data quality or appropriateness of individual datasets. For complete LCA, it is necessary to consider and report on the data quality. In some circumstances, where a dataset is of particular relevance to a study, or where no suitable dataset is available, it may be necessary to collect data from upstream or downstream processes rather than use generic data. The scope of this data collection will depend on the detail required.

EPD programmes may require specific databases to be used for comparability purposes in terms of methodology until EN 15804 compliant data are widely available. Once EN 15804 compliant databases are available, there should be no differentiation between EN 15804 compliant datasets, other than the scope of the data used. It may be advisable to use the background database that is required from the EPD programme that lies within the context of the LCA study. This means that, for improved consistency, a product LCA study may/should be based on the national EPD programme’s background study.

ILCD already provides guidance on sources of generic data such as the ELCD and proprietary databases.

A-01 Distinction between wastes and by-products during the extraction and the processing stages

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Aspect A-01 Distinction between wastes and by-products during the extraction and the processing stages
Description
 Several wastes and by-products are either used or generated during the production phase of building products. A waste is an output from a process that has not yet reached the end-of-waste state. A by-product is an output that is not a waste, but has low value relative to the product or co-products.How should wastes and by-products be handled? Should energy consumption for waste disposal be included? Should processing energy/water and capital equipment/machinery required for waste disposal be included? How should allocation and crediting issues be handled?

related study objective

 ☒ stand-alone LCA ☒ comparative assertion

related study phase

 ☒ ☐ ☐ ☐ ☐
goal and scope definition inventory analysis (LCI) impact assessment (LCIA) interpretation reporting

relevant for
new buildings existing buildings construction products screening LCA simplified LCA complete LCA
Provisions If the goal of the study is to make an EPD, the rules provided by EN 15804 should be followed. This will increase consistency with other studies and with EN 15804-based EPDs.For other goal definitions (other than for EPD), ILCD and EN 15804 should be analysed and the most relevant rules should be selected.
Rules from:

EN 15804

 6.3.4 System boundaries
6.3.4.2 Product stage
6.4.3 Allocation of input flows and output emissions

ILCD

 Provisions: 7.9.2 Avoiding allocation by subdivision or virtual subdivision
Provisions: 7.9.3 Solving multifunctionality by allocation
Guidance
 The following guidance is relevant where an EPD is required according to EN 15804, or where the best possible consistency with EPDs that follow EN 15804 is desired. This is the agreed standard for providing EPD and LCA information for construction products, and for their use in building-level assessments; any regulation in Europe in this area will follow this standard. If there is no interest in understanding the performance of the product according to EN 15804, other approaches – of ISO 14044 and the ILCD Handbook – can be followed. However, these may lead to different results.According to EN 15804, the impacts associated with waste treatment and disposal of wastes are included in the system boundary until the end-of-waste status is achieved.As stated in G-16 Allocation, according to ISO 14040/14044, the ILCD Handbook and the EN 15804 standards, when dealing with systems involving multiple products and recycling processes, allocation should be avoided as far as possible; when unavoidable, allocation should be considered carefully, and should be justified.Allocation cannot be avoided in situations where processes cannot be subdivided and it is impossible to make one product without the other co-products, by-products or wastes.Allocation has to be handled as described in EN 15804, EN 15978 and the ILCD Handbook.

A waste may therefore become a by-product or co-product (with higher value) from the process at the system boundary, and can therefore be considered in terms of co-product allocation according to EN 15804 (see 6.3.4.2), which states: “Flows leaving the system at the end-of-waste boundary of the product stage (A1–A3) shall be allocated as co-products. Loads and benefits from allocated co-products shall not be declared in Module D (see 6.3.4.6). If such a co-product allocation is not possible, other methods may be chosen and shall be justified. Therefore, as a general rule, potential loads or benefits from A1-A3 do not appear in module D.”

EN 15804 does not include the second option for avoiding allocation provided within ISO 14044, “expanding the product system to include the additional functions related to the co-products” (often known as system expansion), but does provide that any use of upstream data that does not respect the allocation principles in EN 15804 “shall be clearly stated and justified in the project report. These data shall be in line with EN ISO 14044 allocation rules.” The basic procedures and assumptions for co-product allocation used in EN ISO 14044 have been refined in EN 15804 to reflect the goal and scope of EN 15804 and EN 15643-2. This is because EN 15804 covers all construction products, and in many cases construction products use co-products, by-products and wastes in their manufacture, as well as producing them during manufacture, construction and at end of life. In this situation, where there is such interdependence, it is not possible to use the process of system expansion, as the impact both of the product and co-products and of recycled wastes is required to provide input data for the product LCA study, not just the impacts of the main product of a process.  EN 15804 also requires, in 6.4.2, that “the same calculation procedures shall be applied consistently throughout the study,” which means that different allocation procedures should not be applied to one upstream dataset than are used for other co-products entering or leaving the system boundary.

Where possible, if there is more than one output from a system, the system should be broken down until the system studied is producing only one output. This is the case where a factory produces two separate products on two production lines – here submetering or other mechanisms such as monitoring should be used to split the inputs and outputs of the system between the two production lines.

However, there are many situations where a system produces two or more outputs. For example, the production of cut stone always results in the production of broken stones and dust; and the production of sawn timber always results in the production of sawdust, bark and waste timber, which can be chipped.

In these instances, the other outputs can be considered as co-products, by-products or wastes, and the allocation should reflect the main purposes of the process. If the wastes are disposed of, and never reach the end-of-waste state, the impacts of disposal are included within the system boundary. If the wastes, after recycling processes, reach the end-of-waste state, the impacts until they reach this state should be included within the system boundary, and the secondary product produced is considered as a co-product for co-product allocation.

If the co-product or by-products are never considered as waste, then they are both considered for co-product allocation at the point where they leave the system.

If the co-products have a similar value (i.e. the comparable prices per unit are within 25% of each other), then EN 15804 states that the impacts can be allocated on the basis of the physical unit of production.

If the co-product’s value varies by more than 25%, then the co-product allocation should be based on economic value, according to EN 15804. All the outputs at the system boundary (including wastes that have been treated to reach the end-of-waste state) are considered in terms of the percentage of revenue (income) they bring to the system. Comparison of revenue from products should be undertaken using the market value of the normal unit of production (e.g. kg or MJ), based on normal pricing units and long-term averages (3 or 5 years) if prices fluctuate. The impacts of the system are then split between them on the basis of these percentages.

For example, in the case of an iron ore mine that produces iron ore and stone that can be used for aggregate, for each kg of iron ore produced and sold for X per kg to be smelted into iron, there may be T tonnes of stone produced and sold for Y per tonne that can be further crushed and used as aggregate.

The impacts of the iron ore mine extraction system are then split between the co-products as follows:

Revenue from iron ore: 1 kg × X/kg = X

Revenue from stone: T tonnes × Y/tonne = YT

Total revenue/kg iron = X + YT

Proportion of impact allocated to iron ore = X/(X + YT)

Proportion of impact allocated to stone = YT/(X + YT)

Note that this approach to co-products and co-product allocation, provided in EN 15804, is different from that described in the ILCD, where a physical causality is assumed for both the iron ore and the stone, and the impacts of extraction would be allocated between the co-products on the basis of mass.

For both the iron ore and the stone, further processing of the iron ore (smelting of the iron ore) would be completely allocated to the iron, and further processing of the stone (crushing to form aggregate) would be completely allocated to the aggregate.

Where the product studied is of high value, a conservative approach in simplified and screening LCA could be to omit the allocation phase and keep all impacts with the high-value product. Where the product studied is a low-value co-product or by-product, it is important to consider the impacts allocated from the production process, as they may still be significant for the low-value product, even if they are only a very small proportion of the high-value product’s impact.

The market value of co-products may change over time, but it is the relation between them over time that is relevant, not the actual values. The actual overall revenue may be sensitive, but it is the percentage of revenue that is required for allocation. Rather than data for the whole plant, it could be considered at the cost of 1 kWh electricity and the cost of the resulting fuel ash etc. It may be clear, for instance, if the fuel ash is not a waste, that its relative value is less than 1% of the cost of the electricity.

Where co-products have incompatible units, e.g. mass and energy, it is essential to use economic allocation.

Wherever possible, market-value data should be obtained from the supplier of the waste or secondary material, or from a relevant local trade association. In many situations an estimate can be made of the values of the different co- products, goods and services, including waste-processing services, if relative values cannot be obtained from the suppliers. If market prices are not known, there are several reliable sources on many product prices, including historical prices and expected prices in terms of futures. The web is a unique source of price data. Hundreds of websites are available on most commonly traded products. The relevant search term for market price is ‘fob’ (free on board at the location of the supplier, without insurance or transport.) The other price type is ‘cif’, stating a specific place of deliverance: e.g. ‘cif Chicago’ for the price of steel as delivered in Chicago.

Sources of relevant and appropriate data will vary, depending on material and location, and should be considered on a case-specific basis.

Manufacturing waste that is recycled into the same cradle-to-gate process can be considered as closed-loop recycling where there is a matching input, but all impacts must be reported in Modules A1–A3. Where the waste output is not sufficient to match the linked recycled input, then additional upstream data for the recycled input must be used. Where the output is more than sufficient to produce the recycled input, then the additional output flow, at the system boundary (end-of-waste state) should be considered as a co-product for co-product allocation.