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Tag: Related study phase: Inventory analysis (LCI)

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 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 (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-24 Collecting foreground and background data for product LCA

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Aspect G-24 Collecting foreground and background data for product LCA
Description
 Different data need to be collected for a product LCA study. The most important data collection is usually the production stage especially for highly complex manufacturing processes. The data can be based on industry or companies involved in the project else on secondary sources e.g. background databases providing average datasets.

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 practitioner should follow ILCD Handbook provisions as well as EN 15804 if more relevant and specific for the goal and scope of the study.The provisions of this aspect is linked to the “definition of system boundaries for product LCA”.
Rules from:

EN 15804

 6.3.6 Selection of data

CEN/TR 15941,

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

ILCD

 The ILCD Handbook provides very useful guidance on this topic. See below the references of the rules (and the quotation of the rules where relevant). Note that the rules from ILCD concerning the definition of system boundaries for products are reported in the corresponding aspect.
Provisions 6.8.2 Technological representativeness
“I) SHALL – Good technological representativeness (…)
III) SHALL – Different technologies for attributional and consequential modelling           III.a) Attributional modelling

          III.a.i) Foreground system: (…) technology-specific primary data. (…) Secondary data of the actual suppliers/downstream actors should be preferred to other (third party) secondary data.

          III.a.i) Background system: average technology as market consumption mix data should be used (…)

          III.c) Using not fully representative data: (…) use justifiable only if this is not relevantly changing the overall LCIA results compared to using fully representative data”

Provisions 6.8.3 Geographical representativeness

“I) SHALL – Good geographical representativeness (…)

II) SHALL – Different technologies for attributional and consequential modelling

          II.a) Attributional modelling

          II.a.i) Foreground system: (…) site or producer/provider specific data  (…) supplier-specific data for the products that connect the foreground with the background system. Generic data of geographical mixes can be used also in parts of the foreground system if for the given case justified as being more accurate, precise, and complete than available specific data (especially for processes operated at suppliers).

          II.a.ii) Background system: average market consumption mix data (…)”

Provisions 6.8.4 Time-related representativeness

“I) SHALL – Good geographical representativeness (…)

II) SHALL – Specific seasonal or diurnal situation?

III) SHOULD – Time-related representativeness of future processes: (…) fully time-representative future data should be used (…). If this is not possible:

          III.a) Best Available Technology (BAT) and recent data (…)”

Provisions 6.9 Types, quality and sources of required data and information

“I) MAY – Overview of the principles types of data and information

II) SHOULD – General requirements on data and data set quality

III) SHOULD – Potential sources for the required data, data sets and information

          III.a) Well documented data

          III.b) Pre-verified data”

Provisions for the foreground system of an analysed system

Provisions 7.3 Planning data collection

“I) SHALL – Identify newly required, study-specific unit processes

II) SHALL – Average and generic data

III) MAY – Identify data and information sources

IV) MAY – SI units

V) SHOULD – Multi-annual or generic data to be preferred?

VI) MAY – Relevance-steered data collection:

(…) Building on existing experience that sufficiently reflects the analysed process or system and that is of high quality is an essential guide. (…) PCR can represent this experience (…).”

 

Provisions 7.4.2.4 Types of input and output flows to collect

“I) SHALL – Types of input and output flows

          I.a) Input of “consumed” products

          I.b) Input of wastes

          I.c) Input of resources from nature

          I.b) Emissions to air, water, soil

          I.b) Other input and output side interventions with the ecosphere

          I.b) Output of wastes

          I.b) Output of valuable goods and services provided by the  process, as product flows”

Provisions 7.4.2.6 Reference amount of the reference flow

Provisions 7.4.2.7 Representativeness regarding operation conditions

“I) SHALL – Full operational cycle of the process, if required

II) SHOULD – One full year as data basis:

for measured data of operated process

III) SHOULD – For parameterised processes”

Provisions 7.4.2.11 Interim quality control

Provisions 7.4.2.11 Emission of particles to air

“I) SHALL – Inventory only poorly water soluble compounds as particles

II) SHOULD –  Differentiate particles size classes

III) SHALL – Inventory particles additionally as the substances they are composed of”

Provisions 7.6 Selecting secondary LCI data sets

“I) SHALL – Use consistent secondary data sets

II) SHOULD – Quality-oriented selection of secondary data sets

III) MAY – Prefer pre-verified data sets

IV) MAY – Prefer well-documented data sets”

Provisions 7.8 Modelling the system

“(…)

II) SHALL – Complete system model (…)

V) SHALL – Use consistent data to fill gaps

(…)”

ISO 14044

 4.2.3.6 Data quality requirements
Guidance
 ILCD guidance should be followed. It needs to be precised that the data collection is a very time consuming step in the LCA. However, this step is highly linked to the overall quality of the study. The practitioner may face different challenges for collecting foreground or background data in practice.Generally speaking, the foreground data collection at the manufacturer plant should follow consistent rules (e.g. see ILCD provisions 7.4.2.8 Checking legal limits; provisions 7.4.2.11 Interim quality control).
General guidance for product LCA studies
The data collection should be conducted depending on the goal and scope of the study.Specific guidance for EPD studies

Depending on the EPD program, some already pre-verified background data may be made available for the practitioner. If so, there is no need to comprehensively review the background data as they are supposed to meet the quality guidelines and goal and scope of the PCR (e.g. EN 15804).

It is very important to comply as much as possible to the specific rules given in the PCR (EN 15804 but also national implementation). One key issue is to know where we need to stop collecting data from the manufacturer. Usually, he controls only the gate-to-gate processes. However, under some circumstances, he may also be responsible of upstream process e.g. extraction of clay. In that context, it may be relevant to collect primary data for this process instead of using secondary data available in background databases.

For the gate-to-gate stage (under the control of the manufacturer), the data collection is function of the type of EPD.

For single manufacturer’s EPD, data can be taken from 1 production site or averaged across more than one the production sites.

For group of manufacturer’s EPD, data are taken from different companies (their data may be already averaged internally if they have more than one production site). They need to be averaged (horizontal averaging according to the ILCD). In that case, it is very important to make sure that the different companies have similar environmental impacts for the production of the product. PCR (in every national context) may provide more specific rules than EN 15804 to calculate these group of manufacturer’s EPD. This issue being to make sure that the declaration is representative of the companies with a limited variability. By requesting a low variability on the final results (e.g. 10% for GWP, 20% for acidification) it leads to differentiate different group of companies that have different technologies and related environmental impacts. Otherwise, the issue is to have a company that has higher impacting production process being hidden under the “average” value thanks to the more efficient/less impacting production processes.

Guidance for E2B EI research projects

Within E2B EI research projects, some confidentiality reasons may lead the use only of generic data for both foreground and background system. In some cases, where the company is keen on giving the gate to gate information for the LCA study, the modelling will be more representative of the product.

The limits encountered during the data collection step should be part of the LCA report. The interpretation of results should be made according to the quality of data collected during the inventory analysis.

G-21 Background databases in LCA studies

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Aspect G-21 Background databases in LCA studies
Description
 According to the ILCD Handbook, the background system comprises those processes that are not under the direct control or decisive influence of the producer of the good. For attributional modelling these are typically processes for both the upstream and downstream parts of the entire life cycle of a product. For comparative assertions, the use of consistent background data is crucial. Generally, a product or a building process tree always includes intermediate flows (according to ISO 14044), such as energy, electricity, transport and raw materials. These processes may be modelled using background data available in generic databases.
In this context, which database should be used for background data in an LCA study? Which database should be chosen, or which rules should be defined for the use of a database for comparative assertions?

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 All data used in an LCA study should be modelled with a uniform methodology. This can typically be achieved by using a public or commercially available background database and modelling the foreground system in a consistent way.For comparative studies (in simplified or complete LCA studies), it is highly recommended, or even essential, to use datasets that are consistent, e.g. consistent within one database. If this is not possible (e.g. because of data gaps or incomplete documentation), any other data should comply with the methodological rules of the database used for the study.
Rules from:
 ILCD
9 Life cycle interpretation
Provisions:
9.3.4 Consistency check
Guidance
 In general, the LCA practitioner should use consistent data from a single source. For European research projects, the use of European databases such as ecoinvent, GaBi, ELCD or ESUCO may be appropriate. The mixing of background data from different databases should be avoided for comparative assertions. This is especially true if data from different databases are not used similarly in the compared models, or if the methodological rules and the quality guidelines do not match between the mixed data.However, in practice the mixing of background data can occur. For example:– if one background dataset (e.g. raw material production, or energy supply) is more representative for the context of the study than the one in the main database being used;– for EPD databases where no mandatory background database is provided. In this case the background data provider should ensure that the use of their data does not lead to bias in the comparative assertions (as the practitioner cannot influence the background data).In general, the use of different background data is not a problem; it is more the adaptation of data in terms of methodology and cut-off rules that can be a problem (for the LCA study). Some databases providing unit process data can easily be adapted to the goal and scope of the LCA study, and to the other background data that cannot be modified, but some databases cannot be adapted in this way.If the lack of specific datasets in a background database leads practitioners to combine data from different literature sources, they need to decide whether it is more important to use a consistent but roughly estimated dataset (and possibly data that are not relevant for the context of the study), or to use a dataset that may be better in terms of representativeness, but which is methodologically inconsistent with the alternative data.In this context, one possible solution is to use data quality indicators for assessing both the representativeness of the data and the consistency of the methodology, compared with the goal and scope of the study: for example, is the dataset compliant with the national context in terms of representativeness?

G-22 (Buildings) / G-23 (Products) Data quality

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Aspect G-22 (Buildings) / G-23 (Products) Data quality
Description Generally speaking, the data quality in LCA refers to the relevance of generic or specific LCA data in accordance with the goal and scope of the study. Depending on the background data sources (literature, industry data), and the boundaries and context of the study (e.g. for which purposes or countries are the data being used?), the data quality can be very different within one study. Although data may be of good quality for context Y, this will not necessarily be the case for context Z, as the requirements (e.g. geographical representativeness) may be different. The practitioner should keep in mind that data quality is always a relative concept. In order to point out this aspect as transparently as possible, the quality of the data has to be justified in the context of its use.How should the quality of the LCA data be described, and can the practitioner ensure that data of a specific quality are needed and produced?

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 The data quality of LCA studies should at least meet the requirements of EN 15978 and En 15804, and the documentation, nomenclature, method and review should be implemented accordingly.
Rules from
 EN 15978
10.3 Data quality
Different criteria are given in EN 15978, e.g. technological, geographical and temporal coverage (the data should be not older than 10 years). The data should be based on a one-year average (if relevant); check the plausibility and the significance of the data in the final result.

EN 15804
6.3.7 Data quality requirements

ILCD

6.8 Representativeness and appropriateness of LCI data provisions
6.8.2 Technological representativeness
Provisions 6.8.3 Geographical representativeness
Provisions 6.8.4 Time-related representativeness

12 Annex A: Data quality concept and approach

12.1 Introduction and overview
In the ILCD Handbook, two approaches are defined – 1) data quality in a stricter sense; and 2) the data quality documentation and review:

1) ILCD overall data quality indicators include: technological, geographical, time-related representativeness, completeness, precision/uncertainty, methodological appropriateness and consistency.

2) Data quality documentation aspects cover: documentation, review, nomenclature (e.g. same list of elementary flows)

12.2 Data quality aspects
The ILCD Handbook defines ‘accuracy’ as a term covering all the related data quality aspects, such as:

“Representativeness (technological, geographical, time-related)
Completeness
Methodological appropriateness and consistency”

The ILCD Handbook also provides rules for not mixing the data quality aspects (falling under the term ‘accuracy’) with the other concept of ‘precision’ (or ‘uncertainty’). A graphical illustration (see Figure 11) illustrates this point.

Figure 11: Concept of precision

ISO 14044
4.2.3.6.2. Data quality requirements
Guidance
 In current practice it is usually not possible to choose datasets for quality reasons, but for availability in the construction sector. The practitioner should keep in mind that data quality is crucial for the LCA study. The most appropriate data should be chosen (in terms of representativeness and consistency) as far as possible. Documentation of the used datasets and the quality level is needed as far as possible.The ILCD Handbook provides some recommendations on data quality, depending on the relative significance of the data in the final results. A graphical illustration (see Figure 12) illustrates this point.Figure 12: Focusing efforts on key data

For product LCA, the user of commercial software can also find information on data quality in the documentation for the LCI data used for the process tree of his LCA study.

For building LCA, in dedicated LCA software, information on data quality may not be currently available. The practitioner should, however, be cautious when using LCA data (check whether a methodological report is available, check whether  a critical review or verification was done, assess whether the data are relevant for the context of the study etc.).

In practice, the data quality assessment should be conducted according to the goal and scope of the LCA study. For instance, an LCA study of a building within a European project may require the use of generic European datasets from available LCA databases (ecoinvent, ELCD, ESUCO etc.). By contrast, a screening LCA study in a national context may require the use (if available) of generic national LCA data on building materials, and on components sold on the national market (i.e. representing the ‘consumption mix’ according to ILCD).

For building LCA, the data quality assessment can be conducted at two levels:

– a data quality check for the entry data (depending on the goal and scope of the study) by means of data quality indicators, e.g. A, B, C, D that may be based on the Pedigree matrix [Weidema 1996];

– a data quality check for the LCA results for buildings (depending on the contribution analysis). In this case, if a building material accounts for 1% of, say, the acidification potential indicator, and the data are not very precise or accurate (e.g. generic data, randomly selected), it does not matter. Conversely, if a key building material (e.g. reinforced concrete) accounts for 45% of, say, the GWP indicator, and the data are not of high quality, the practitioner should possibly refine the LCA data, as it is sensitive to the results. These examples are also valid for LCA data on energy and water processes (e.g. fuel, electric mix, water treatment processes), as they may also drive most of the impacts of a building.

G-23 Choice of LCI/LCIA datasets for screening LCA

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Aspect G-23 Choice of LCI/LCIA datasets for screening LCA
Description
  Different LCI/LCA data are needed to assess the environmental impacts of buildings. They make it possible to quantify the different impacts related to the building products and equipment, the construction site, the operational energy and water uses, and the deconstruction of the building. Depending on the study type (screening, simplified, complete), different types of data can be used in practice, depending on their availabilities at the European level but also in a national context (average, generic or specific LCI/LCIA data for the building materials, products and processes).How can this be addressed for screening LCA?

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 The LCA practitioner or the user of dedicated building LCA tools should use adapted data for the description of the building components in screening LCA.They can either represent a major part of the building (e.g. statistical data, such as a specified level of kWh/m² for the interior walls), a full building component (e.g. 1 m2 concrete block wall insulated with wood wool), a building product (e.g. 1 m2 of rock wool) or a building material (1 m3of ready-mixed concrete), depending on the need of the practitioner and the stage of the building project. Provisions for the choice of data to use for screening LCA for the construction site, the operational energy and water uses, and the deconstruction activities are described in the corresponding aspects.
Generic LCA data for the building elements cited above should come from available European or national generic LCA databases where the building is built. It is possible to use average data (e.g. average EPD) if generic LCA are missing, or are less appropriate to the context of the study. Generic LCA data may represent (if possible and if relevant) the total consumption mix in Europe (if the study is used for European projects) or in every European country, or the production mix in Europe or in every European country, or the production mix of a neighbouring country using appropriate rules to adapt the generic data to the new context.
Rules from:
 EN 15978
9.4 Type of data for the assessment
The type of LCA data for the assessment referred in EN 15978 to CEN/TR 15941. The choice of the data will depend on several aspects, including the stage of the building project, the intended use/scope etc. According to EN 15978 the data (bill of quantities, building description of components, or the LCA data) may be given in different types: aggregated, specific, generic, or average. They describe different levels of specificity concerning the description of the building components as well as the representativeness of the LCA data.

ILCD

7.5 Developing generic LCI data

7.6. Selection of secondary LCI datasets

7.7 Averaging LCI data

According to the ILCD Handbook, a dataset is a generic dataset if “it 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 judgements etc. Generic process can aim at representing a specific process or system or an average situation.”

ILCD also states that “a generic data represents a typical variant of the process or the system, an average dataset represents the average situation for the process or the system, in both cases within a specified geographic region and time. The difference lies in how the dataset 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 technology or production plants) are separately modelled and the inventories are subsequently averaged.”
Guidance

In practice the data for a screening LCA can be based on generic assumptions, as they are used only for obtaining a rough estimate of the environmental impacts of a product system. Three different practical recommendations can be given for the use of data on the building elements, the associated LCA data and the currently available generic LCA databases.

1) Practical guidance for the use of data describing the building elements

The data describing the part of the building can be estimated using either the statistical results of a comprehensive study of newly constructed buildings, or a sample of representative buildings.

The data describing the building components can correspond to generic typical components, using default values for the main included products (width, thickness etc.). It may be possible to parameterize the thickness of the key included products (e.g. insulation or structural products) for each study or use.

Other data include building products and materials LCA data. These ‘raw’ data usually serve when deriving data for building components or part of the building. Consistency should be ensured between the different levels of data (part of the building, components, products and materials).

2) Practical guidance for the use of generic LCA data for a European or national context

Examples of generic data on building products representing the ‘consumption mix’ can be found, for example, for the reinforcing steel sold on the French market in [Gomès 2012]. However, generally speaking, generic national data representing the ‘consumption mix’ in the various European countries may be missing. In this case, the use of existing generic LCA data (from neighbouring European countries) or industry-based data (from the national context) can be used as proxy data, using appropriate adaptation/contextualization rules. More guidelines on this topic can be found e.g. in [Hodkova 2012].

3) Practical availability of generic databases in Europe that can be used by the practitioner

The building practitioner may use existing European or national databases to collect generic LCA data to describe the building elements, products and materials, depending on the needs. Examples of such databases can be found e.g. on the LCA resources directory of the European Commission – Joint Research Centre, section Databases’.Generic databases (mainly at the global or European levels) include, for example, ELCD, ESUCO and ecoinvent.

Other generic databases developed in some European countries include, for example: the German Ökobau.dat, the Swiss Catalogue Construction/KBOB databases, the French DIOGEN generic LCA database for construction materials used in civil engineering applications, and the various generic databases that are included in LCA software for buildings.

G-24 Choice of LCI/LCIA datasets for simplified LCA

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Aspect G-24 Choice of LCI/LCIA datasets for simplified LCA
Description
 Different LCI/LCIA data are needed to assess the environmental impacts of buildings. They make it possible to quantify the different impacts related to the building products and equipment, the construction site, the operational energy and water uses, and the deconstruction of the building. Depending on the study type (screening, simplified, complete), different LCI/LCIA data can be used in practice, depending on their availability not only at the European level but also in a national context (average, generic or specific LCI/LCIA data for the building materials, products and processes).How can this be addressed for simplified LCA?

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 LCA practitioner or the user of dedicated building LCA tools should use adapted data for the description of the building components in simplified LCA.In contrast with screening LCA, the data should reflect more closely the building element, product or material. They can either represent a full building component (e.g. 1 m2 concrete block wall insulated with wood wool), a building product (e.g. 1 m2 of rockwool) or a building material (e.g. 1 m3of ready-mixed concrete), depending on the need of the practitioner and the stage of the building project. Provisions for the choice of data to use for simplified LCA for the construction site, the operational energy and water uses, and the deconstruction activities are described in the corresponding aspects.Generic LCA data for the building elements cited above should come from available European or national generic LCA databases. It is possible to use average data (e.g. average EPD) if generic LCA are missing, or are less appropriate to the context of the study.

Generic LCA data may represent (if possible and if relevant) the total consumption mix in Europe (if the study is used for European projects) or in every European country, or the production mix in Europe or in every European country, or the production mix of a neighbouring country, using appropriate rules to adapt the generic data to the new context.
Rules from:

EN 15978

 9.4 Type of data for the assessment
The type of LCA data for the assessment referred in EN 15978 to the CEN/TR 15941. The choice of the data will depend on several aspects, including the stage of the building project, the intended use or scope etc. According to EN 15978 the data (bill of quantities, building description of components or the LCA data) may be given in different types: aggregated, specific, generic or average. They describe different levels of specificity concerning the description of the building components as well as the representativeness of the LCA data.

ILCD

 7.5 Developing generic LCI data
7.6. Selecting secondary LCI datasets
7.7 Averaging LCI data
According to the ILCD Handbook, a dataset is a generic dataset if “it 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 judgements etc. Generic process can aim at representing a specific process or system or an average situation.”

ILCD also states that “a generic data represents a typical variant of the process or the system, an average dataset represents the average situation for the process or the system, in both cases within a specified geographic region and time. The difference lies in how the dataset 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 technology or production plants) are separately modelled and the inventories are subsequently averaged.”

According to ILCD, the supply mix for an average data is the production mix plus the import mix, i.e. the mix of what is available in the country for consumption. This applies to generic such as the consumption mix of reinforcing steel in country A.

Figure 13 presenting the trade relations between countries as a basis for calculating the production, consumption and supply mixes of products [ILCD 2011a]
Guidance
 In practice, the LCA data for a simplified LCA should represent the building elements, products or materials more closely than the data used for a screening LCA. Three different practical recommendations can be given for the use of data on the building elements, the associated LCA data and the currently available generic LCA databases.

1) Practical guidance for the use of data describing the building elements

The data describing the building components can correspond to generic typical components using default values for the major included products (width, thickness etc.). It may be possible to parameterize the thickness of the key included products (e.g. insulation or structural products) for each study or use.

Other data include building products and materials LCA data. These ‘raw’ data usually serve when deriving data for building components or parts of the building. Consistency should be ensured between the different levels of data (part of the building, components, products and materials).

2) Practical guidance for the use of generic LCA data for a European or national context

Examples of generic data on building products representing the ‘consumption mix’ can be found e.g. for the reinforcing steel sold on the French market in [Gomès 2012]. However, generally speaking, generic national data representing the ‘consumption mix’ in the various European countries may be missing. In this case, the use of existing generic LCA data (from neighbouring European countries) or industry-based data (from the national context) can be used as proxy data, using appropriate adaptation or contextualization rules. More guidelines on this topic can be found e.g. in [Hodkova 2012].

3) Practical availability of generic databases in Europe that can be used by the practitioner

The building practitioner may use existing European or national databases to collect generic LCA data to describe the building elements, products and materials, depending on the needs. Examples of such databases can be found e.g. on the LCA resources directory of the European Commission – Joint Research Centre, section ‘Databases’. Generic databases (mainly at the global or European level) include, for example, the ELCD, ESUCO and ecoinvent databases.

Other generic databases developed in some European countries include, for example: the German Ökobau.dat, the Swiss Catalogue Construction/KBOB databases, the French DIOGEN generic LCA database for construction materials used in civil engineering applications, and the various generic databases that are included in LCA software for buildings.
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