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Tag: Study type: Simplified LCA

2.3 Procedure for choosing provisions from both CEN TC 350 standards and the ILCD Handbook

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The ILCD Handbook was written by a panel of scientific researchers and experts in LCA, whereas the CEN TC 350 standards were written by a panel of building stakeholders as well as LCA experts. The level of detail varies considerably between the CEN standards (around 50 pages) and the ILCD Handbook (around 1000 pages in total). The main differences between the ILCD and CEN TC 350 standards can be found in their terminology and provisions. For example, EN 15804/EN 15978 proposed new terms such as the ‘functional equivalent’ of a building to adapt the ‘functional unit’ term defined in ISO 14040 and in the ILCD for the building sector. As a result, these documents may often conflict in the definition, the level of detail and finally the provisions to adopt for each LCA step, and for each life cycle stage. A systematic procedure was therefore adopted in the EeBGuide for choosing the basis of the guidance included for each aspect.

As mentioned above, the EeBGuide tries to combine provisions and guidance from the EN 15804 and EN 15978 standards and the ILCD Handbook (see Figure 5). If cases of contradictory approaches appear in the reference sources, then the EeBGuide always tries to state a provision or guidance transparently for both the standard and the ILCD Handbook. As far as possible, the EeBGuide provisions follow the European standards [EN 15804] and [EN 15978] closely. If the standard does not mention a certain aspect, or if it is not very clear on that aspect, provisions and guidance from the ILCD Handbook are provided. Where no existing guidance is available, other provisions are proposed by the EeBGuide.

Figure 5: Procedure for adaptation from the CEN TC 350 standards and ILCD Handbook

Guidance can include links to further interesting or important information, or to examples, or present an interpretation of the standard or the ILCD Handbook. This interpretation is not meant to be a provision, but rather a means to share LCA experiences from LCA practitioners and experts.

2     Methodological approach of the EeBGuide.

2.4.2 Simplified LCA

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Purposes

A simplified LCA study can be conducted for a quick assessment of a building or a product. The challenge is to adapt the LCA methodology and simplify its use, but to a more advanced LCA stage than for a screening LCA. With a simplified LCA, a pragmatic approach is applied to a building or product LCA. It makes possible studies based on information that is already available, e.g. in the planning process. The simplified LCA lies somewhere between the screening LCA and the complete LCA. It may be adapted by the practitioner or the building stakeholder (e.g. the construction company or the design engineer), and to a given stage of the building planning process. For example, if a construction company conducts a simplified LCA, more precise data can be used for the on-site related impacts, but the study can still rely on the definitions of the screening LCA for the other life cycle stages.

The simplified LCA has to be interpreted as an ‘adapted’ LCA, depending on the effort that the LCA practitioner wants to put in for every life cycle stage and contributor.

Completeness of assessment

The main focus here is on the major contributing input materials, water and energy use. More details should be given, compared with a screening study, in order to increase the representativeness of the study’s results. It is also important to use adapted calculation rules for simplified LCAs (e.g. the possible use of dynamic thermal simulation for assessing operational energy use). More information on the calculation rules can be found in Table 5. The study may consider a more comprehensive set of environmental impact categories than for a screening LCA, for example taken from both EN 15804 and EN 15978, and additional indicators described in the ILCD Handbook (if relevant for the purpose of the study).

Cut-off rules as specified in EN 15978 and 15804 may not apply to simplified LCA studies for buildings, products or services. In early design, for example, not all the input raw materials and components are known in detail, so that some of them have to be omitted. Rather than systematically neglect them, one option is to try to model them using default values . However, life cycle modules, inputs and services should be omitted only if a scientific justification shows their insignificance for the corresponding environmental indicator.

Data representativeness

Compared with a screening LCA, the data used for simplified studies should be more representative of the product, component, element or part of a building under assessment.

Geography

The data used in a simplified study should, as far as practicable, given the existing time and budget constraints, relate to the country where the building or building products are produced or being used. However, as this is not always possible, it is also acceptable to use assumptions, for example using data that represent a country with a similar electric energy grid mix and manufacturing technology. When the goal of the study is to conduct an LCA study within a European project, it is also possible to use average European data, as they are more relevant. The use of global average data should be avoided wherever possible. These provisions do not apply to data on energy, water and waste treatment processes, as national data are preferable (e.g. electric mix, natural gas); or European data can be used if relevant.

Technology

The data should represent the technology used as closely as possible. If no directly applicable dataset is available, a justification for the selection of a dataset should be given.

In the trade-off between the geographical and technological representativeness of data, careful consideration should be given to using the most appropriate data. No general preference can be given here, as this is directly dependent on the geographical and technical parameters.

Precision

Specific, quantitative environmental information on f building elements, products, materials, components or services should be used wherever possible. EPDs of average products may be used, as well as generic LCA data (e.g. if additional impact categories need to be assessed). For other sources of impacts related to the operational energy, water and the construction site, refer to the provisions given in the guidance document.

Consistency

A qualitative assessment of whether the LCA methodology is applied uniformly to the various components and processes should be made in relation to the goal and scope of the study.

Documentation

Use the reporting template provided. The minimum requirements for items reported on can be summarized as follows:

  • Definition of goal and scope
  • Life cycle stages included, and a clear definition of the system boundary
  • Input materials/items included and excluded, with justification, as well as processes for energy, water etc.
  • Overview of calculation rules, and comments on the degree of approximation/uncertainties
  • Impact categories considered (with justification)
  • Limitations
  • Life cycle impact results and interpretation
  • Statement regarding consistency
  • Results
  • Review statement

Communication of LCA report and results

Communication can be internal or external. For external communication purposes, an independent review is needed before publication.

Special precautions have to be taken, if it is intended to conduct comparative assertions on the basis of a simplified LCA. The comparability of the focus areas of a simplified study has to be ensured, and the parameters used and assumptions made for the comparison have to be documented in sufficient detail. The limitations of representativeness have to be estimated, reported and discussed, with regard to the consequences for the comparison.

When performing comparative LCA studies, the same functional equivalent should be used, and similar system boundaries have to be applied to each product system.

Examples of a simplified LCA:

  • Building LCA study for labelling schemes.
  • LCA of a building conducted by a stakeholder (e.g. environmental engineer, construction engineer, etc.) interested in getting a more detailed advanced assessment than from a screening LCA.
  • LCA for developing an environmental fact sheet for a specific product.

2     Methodological approach of the EeBGuide.

3.1.1 Implementation of the study type definitions

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Table 5 gives specific information about how the three LCA study types (screening, simplified and complete) are currently implemented within the EeBGuide framework. Screening describes the first approach, where most of the information on the building is still very rough (e.g. within the design stage): thus default values of generic assumptions need to be chosen and used. In a simplified LCA study, detailed data are used, and a greater number of life cycle stages are addressed. Complete LCA reflects the most comprehensive and detailed application of the LCA methodology. For each level, Table 5 highlights those modules that are mandatory, optional because of their minor relevance, or optional because of currently missing data. The term ‘mandatory’ here specifically relates to projects of the Energy-Efficient Buildings Initiative (E2B EI). For other projects, or for the secondary audience of EeBGuide, this can be considered as a guideline.

Note: The term ‘product’ refers to building-related products, construction materials, components and services.

Table 5: Implementation of the different study types for buildings

3     How to use this guidance document

3.1.1 Implementation of the study type definitions

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Table 5 gives specific information about how the three LCA study types (screening, simplified and complete) are currently implemented within the EeBGuide framework. Screening describes the first approach, where most of the information on the building is still very rough (e.g. within the design stage): thus default values of generic assumptions need to be chosen and used. In a simplified LCA study, detailed data are used, and a greater number of life cycle stages are addressed. Complete LCA reflects the most comprehensive and detailed application of the LCA methodology. For each level, Table 5 highlights those modules that are mandatory, optional because of their minor relevance, or optional because of currently missing data. The term ‘mandatory’ here specifically relates to projects of the Energy-Efficient Buildings Initiative (E2B EI). For other projects, or for the secondary audience of EeBGuide, this can be considered as a guideline.

Note: The term ‘product’ refers to building-related products, construction materials, components and services.

Table 5: Implementation of the different study types for buildings

G-01 Goal definition for building and product LCA

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Aspect G-01 Goal definition for building and product LCA
Description
 According to ISO 14040-44 and the ILCD Handbook, the goal definition of a study is a key LCA requirement, as it guides all the detailed aspects of the scope definition, which then determine the LCI and LCIA provisions. Special attention should be paid to this first step of the LCA methodology, which will influence the study results and determine their applicability. Generally speaking, the goal definition should be documented in detail.How can the practitioner set up the goal of the study? Are there special cases where the effort of goal definition can be simplified in regard to product or building LCAs?

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 goal definition for a building or product LCA study should be defined according to the ILCD Handbook (e.g. by defining the context and the intended use of the assessment).The documentation should also be in line with ISO 14044, EN 15978 and EN 15804.
Rules from:

EN 15978
  • 6 Purpose of the assessment
  • 7 Specification of the object of assessment

EN 15804
  • 5.1 Objective of the PCR

ILCD

 5 Goal definition – identifying purpose and target audience 
Provisions: 5.2 Six aspects of goal definition

  • I) SHALL – Intended applications
  • II) SHALL – Limitations of study
    • II.a) Impact coverage limitations
    • II.b) Methodological limitations
    • II.c) Assumption limitations
  • III) SHALL – Reasons for study
    • III.a) Internal
    • III.b) External
    • III.c) Database developer perspective
  • IV) SHALL – Target audience of study
  • VI) SHALL – Comparisons involved?
  • VII) SHALL – Commissioner

Provisions: 5.3 Classifying the decision context

  • Provisions 5.4: Need for flexibility versus strictness
  • I) SHALL – Product-group and process-type specific guides and PCRs
    • I.a) Need for specific guides and PCRs
    • I.b) Specific guides and PCRs overrule ILCD Handbook

Provisions 5.5: Optionally extending the goal

  • I) MAY – Extending the goal?

15 Annexe D: Avoiding misleading goal and scope definition and results interpretation
Guidance
 Goal definition is a crucial aspect of each LCA study. The practitioner should note that this step has implications for all the following general aspects: scope of the study, life cycle inventory analysis, impact assessment, interpretation, reporting and critical review, as well as all the life cycle stage aspects of products and buildings (i.e. aspects for Modules A, B, C and D according to EN 15804/EN 15978). As a result, it is directly connected to all the provisions/guidance provided in the EeBGuide.Guidance for specific aspects of the goal definition are given in the other EeBGuide aspects ‘Comparative assertions,’, ‘Classifying the decision context as situation A, B and C for building and product LCA’ and ‘Future technical development and innovation’.The goal of the study needs to be defined at the beginning of the study and should – with regard to the relations mentioned below – clearly state the objective of the study. Typically, a study cannot adequately address several different goals, but should address one single goal. If several goals are pursued when conducting LCA studies, e.g. within one research project, separate studies – possibly based on a common basic product model – should be conducted.

1) General guidance: need for flexibility versus strictness
The goal definition applied in the building sector should be handled with care, as many different uses of LCA can be found. This general guidance follows ILCD ‘Provisions 5.4: Need for flexibility versus strictness’.One the one hand, when the purpose of the study is to make an EPD or to produce a building LCA for certification purposes, there is a need to ensure that consistent rules are applied. This is called ‘strictness’ by the ILCD Handbook. These goal definitions are likely to be related to situation A (i.e. attributional LCA; see the corresponding aspect ‘Classifying the decision context as situation A, B and C for building and product LCA’). In this context, the goal is typically predefined (e.g. ‘to conduct a building LCA for certification purposes’); however, for a research-project-related building LCA, for instance, the goal will have to be defined directly by the LCA practitioner.On the other hand, when the purpose is to perform comparative assertions of policy options, e.g. for the different future grid mix options due to the use of renewables, there is a need for flexibility. In this example, several scenarios can be conducted including different LCI modelling principles. These goal definitions may be related to situation A or B (see the corresponding aspect ‘Classifying the decision context as situation A, B and C for building and product LCA.’).

2) Practical guidance for building LCA studies

The goal definition needs to clarify the core objective of a building LCA. This goal may be predefined, e.g. by a building certification system, to provide the building LCA for certification purposes. In general, the practitioner needs to define the study’s goal individually.

This definition of the goal serves as the basis for the identification of the study’s scope, which in turn yields the coverage of different contributors to include in the LCA study, such as the building products (Modules A, B, C, D), construction site (Module A5), energy consumption (Module B6), water consumption (Module B7), transport of people (during the use phase of the building) etc.

For building LCA, the EN 15978 guidance should be used by LCA practitioners to define the goal and scope of their study according to the purpose of the assessment. Three applications are identified in EN 15978:

  • assistance in a decision-making process, e.g. comparison of design alternatives;
  • declaring performance with respect to legal requirements;
  • documenting the environmental performance of a building, e.g. for use in labelling.

3) Predefined goal for product and building LCA studies according to EeBGuide study types

The definition of the goal of a study within the context of this guidance document is also broadly predefined through the use of the three study types (screening, simplified and complete LCA). The reporting templates of the EeBGuide also help regarding documentation of the goal of an LCA study.

However, the study type (e.g. screening LCA) may be adjusted, depending on the practitioner. This is the reason why the provisions and guidance for the corresponding aspects remain flexible. For example, for the choice of LCA data for a screening LCA, the EeBGuide recommends using different types of data. Architects may prefer to use building components (e.g. 1 m2 of wall, with the possibility of changing the width of structural and insulation products), whereas a construction company may prefer quantifying the impacts of a building design at the level of materials (e.g. kg of steel, or m3 of concrete).

4) Practical guidance for product LCA studies within E2B EI research projects

Within E2B EI research projects, it may be interesting to extend the goal of the project, if relevant. For example, for a product LCA, the primary goal may be to develop a product system model as well as delivering a full LCA study for a specific purpose, such as identifying the environmental impacts of a building design or of a novel product.

In some cases, however, the goal might be required to be extended to secondary applications, e.g. developing an EPD for the corresponding product, or providing the LCA study for building certification purposes. In this case, the same life cycle model can be used if it is suitable according to the relevant PCR (e.g. EN 15804), or to the set of LCA calculation rules of the relevant building certification scheme. The main advantages of extending the goal from the beginning of the study is to reduce the additional effort in e.g. data collection, methodological choices (e.g. use of parameters), reshaping of the product model etc.

However, this type of extension of the goal might be difficult to achieve for innovative products where no detailed PCR exist. In such cases the study should at least comply with the major requirements of the core European PCR (e.g. EN 15804) if the secondary goal is to provide an EPD. In addition, the definition of several goals for a study may make it difficult for the practitioner to meet all the study’s objectives. A trade-off needs to be found between reduced effort through integration of secondary goals and increased effort due to e.g. increased flexibility required of the product model, or multiple results.

G-02 Classifying the decision context as situation A, B, and C for building and product LCA

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Aspect G-02 Classifying the decision context as situation A, B, and C for building and product LCA
Description
 The ILCD Handbook distinguishes between different decision contexts for LCA studies. This distinction is part of the goal and scope definition of an LCA study, and has major implications for further definitions of system boundaries and modelling principles, etc. According to the ILCD Handbook, situation A modelling is defined as ‘micro-level decision support’, whereas situation B is characterized as ‘meso- and macro-level strategic (‘policy’) decision support’. Thus situation A refers primarily to product- or process-related decision support studies, whereas situation B applies to strategic decision support studies. It is important for practitioners, to understand under which situation an LCA study has to be established. In addition, the differentiation of when to use situation A or situation B might be unclear in the building sector.

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 Situation A (attributional LCA) should be used for individual product or building LCA studies that do not have a major influence on the background system (such as the energy supply).Situation B (consequential LCA) should be used in modelling specific cases where macroeconomic systems are significantly affected through the use and the dimension of the assessed technology. If an LCA study is believed to be related to situation B, the ILCD Handbook and LCA literature should be consulted for guidance on how to proceed.
Rules from:

ILCD:

5.3 Classifying the decision context as Situation A, B, or C

Table 7: Combination of two main aspects of the decision context: decision oriented and type of consequences in background system or other systems [ILBD 2010a]

Provisions: 5.3 Classifying the decision context

Provisions: 6.5.4 LCI modelling provisions for Situations A B, and C

 

Some examples of situation A, B and C modelling are mentioned in the ILCD Handbook.

Situation A refers to single product assessments that will not change the background system (e.g. when it refers to a limited share of the total production of an industrial sector). The most relevant application of situation A (micro-level decision support) are:

  • ecodesign/simplified LCA;
  • development of specific, average, generic unit process or LCI results for the identified intended applications under situation A;
  • development of Product Category Rules;
  • development of a life-cycle-based Type III environmental declaration (EPD) for a specific good.

Situation B refers to life-cycle-based decision support that will have consequences outside the analysed system boundaries via market mechanism changes. The most relevant applications of situation B (meso/macro-level decision support) are:

  • policy development (e.g. spreading renewable energy technologies or not; forecasting unconventional technology development in the future);
  • policy information (e.g. identifying product groups with the largest environmental improvement;);
  • development of specific, average, generic unit process or LCI results for the intended applications identified under situation B.

 

For unclear situations, the ILCD Handbook gives the following advice:

“In this situation, the guiding criteria shall be whether the consequences of the analyzed decision alone are big enough to overcome related thresholds and/or other constraints and result in large-scale consequences in the installed production capacity outside the foreground system. Then: Situation B. If not: Situation A.”

The last option is to use situation C “Accounting” if the LCA is not intended to be used as for decision support. Situation C1 (“including interactions with other systems”) is distinguished from situation C2 (“excluding interactions with other systems”). “The most relevant applications are e.g. for C1:

  • Monitoring of environmental impacts of a nation, industry sector (only for situation C1);
  • Policy information (identifying product groups with the largest environmental impact);
  • Corporate or site environmental reporting”
Guidance
 Most of the LCA studies published in the building sector have used the LCA approach called attributional modelling (or situation A in ILCD). This type of modelling is the most familiar to the LCA practitioner. Alternative modelling choices are available, especially consequential modelling (or situation B in ILCD). This modelling approach assesses the consequences of the introduction of a new technology or new processes by looking at the marginal effects. The questions addressed are different in these two modelling approaches.An attributional LCA assesses the environmental impact of one quantity unit or one piece of a product. Any scaling-up of the environmental impacts of this product is linear. This means that the environmental and technical consequences (and possibly also the economic consequences) of the life cycle of the assessed system are seen not to have significant impacts on other technical systems, products, etc. This is often seen as a feasible simplification in the process of modelling parts of the real world.A consequential LCA, by contrast, assesses the environmental impacts of products or technologies with consideration of the indirect effects, i.e. by assessing the consequences of the assessed life cycle on other systems. As an example, the assessment of biofuel might include the consequences of increased pressure for the available land in tropical forests due to energy crop harvesting, or include the assessment of consequences of a shift of technologies due to the reduced availability of one rare earth.

Conducting a consequential LCA may result in special requirements for LCA background data, and typically increases the options or choices within the assessed system. As a consequence, the LCA practitioner is required to make an increased number of assumptions, which may reduce the significance of a result.

The European standards EN 15804 and EN 15978 do not consider consequential LCA. It may be valid for specific cases to conduct a consequential LCA, but for the most common applications of LCA in the building and construction sector an attributional LCA should be the method of choice. If a consequential LCA is conducted, the LCA practitioner needs to fully understand the related methodologies, and therefore make him or herself thoroughly familiar with the corresponding literature.

1) Guidance for the choice between attributional and consequential LCA in the building sector

The practitioner should use attributional LCA (situation A in the ILCD Handbook) for the following applications:

  • development of PCR or EPD of building products and technical equipment;
  • LCA used for ecodesign of an individual product or building.

The practitioner may use consequential LCA (situation B in the ILCD Handbook) for the following applications:

  • building sector policy development (e.g. assessment of the marginal effects of a widespread development of renewable energies or new technologies for products; orientation of new environmental regulations).

Situation C is unclear in the ILCD Handbook, as it is intended not to have a decision support. However, even an internal LCA study in a company always has support, such as benchmarking, or improvement potentials. Generally speaking, most of the time the LCA practitioner in the building sector will rely on situations A or B.

Whereas a single product or building does not change the background system very much (situation A), this will no longer be the case when all the building sector is considered. For example, in France, where many buildings are heating by using electricity, this leads to a winter peak demand when thermal power plants are turned on, resulting in increased CO2 emissions [Peuportier 2008]. Assessing the entire building stock should relate to a situation B decision context. Under the specific goal and scope, situation B may be used for individual systems that are large enough to potentially influence the background system.

2) Guidance for studies complying with goal and scope definition according to EN 15804/EN 15978

EN 15978 and EN 15804 relate solely to attributional LCA studies. As a result, provisions and guidance that are in line with these standards in terms of scope definition and inventory analysis refer only to situation A (attributional modelling) in the EeBGuide.

3) Specific guidance and current limits for consequential LCA

The use of situation B needs appropriate LCI data. Usually, the practitioner may rely on background databases (providing consequential datasets). The practitioner can refer to the provision ‘6.5.4 LCI modelling for Situations A, B, and C’ for more guidance and rules.

In the LCA community, there is no commonly agreed understanding on how to decide which type of decision context situation should be applied. This is especially true for medium-scale systems (e.g. a neighbourhood or a district) for which no strict recommendations are given in the ILCD Handbook. In these cases, the use of a situation A or B should be justified by providing evidence e.g. on the possible modifications on the background system.

As the distinction between attributional and consequential LCA is currently a much-discussed topic, the practitioner may also be interested in referring to the recent review articles published by [Frischknecht 2010], [Earles 2011] and [Zamagni 2012]. According to [Zamagni 2012] there are still several issues to address in consequential LCA, including the selection of appropriate data, the identification of market mechanisms, and the affected processes that should be included in the system boundaries. The authors state that scenario modelling can be a useful approach in dealing with present mechanisms and future developments. Scenarios can be predictive (what will happen?), explorative (what can happen?), or normative (how can a specific target be reached?).

G-03 Future technical developments and innovation

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Aspect G-03 Future technical developments and innovation
Description
 This aspect includes the possibility of considering the effects of future developments with regard to technologies, materials and end-of-life options (e.g. scenarios on energy recovery, or recycling) within a building LCA. In the current business world, technologies and production techniques are changing rapidly. In contrast, building and product LCAs are based on today’s available technology (the precautionary principle). Some major technical systems may change significantly within the coming decades. Hence a modelled option may be preferable, based on today’s general conditions, but may not be the preferable option under future conditions.How can technical developments and innovation be dealt in product or building LCA studies?

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 EPDs for building products, and building-level LCA assessments, are based on the attributional LCA approach, and the European standards developed for the industry are clear that they should be considered on the basis of current practice. EN 15978 mentions that technologies should be rated by economical and technical feasibility. EN 15804 emphasizes that the scenarios should be practical, and be based on today’s technology. This reflects the baseline scenario.Where relevant, alongside EPD and building-level LCA studies, the effect of changes of production techniques, materials etc. may be shown by a separate scenario within a sensitivity analysis. All assumptions have to be documented, and should be based on reliable sources. For comparative assertions the consideration of future developments should be avoided or, where they are considered, they must be treated in the same way for both product systems.Future developments may be described within separate scenarios, where:

  • the assumptions made are justified;
  • the assumptions are documented transparently;
  • a sensitivity analysis has been conducted and reported by comparison with the baseline scenario;
  • the external review comments on this assessment of future developments are included.

The above restrictions are valid for EPD, and in ILCD the comparative goal justifies certain limitations. In some circumstances, however, the goal of the LCA for a product or building may be to understand the effect of a future development and its implications – for example, what is the implication of a changing energy mix for a highly insulated building or an energy-using product? In these circumstances it can be appropriate to consider the effects of future technology. If this type of LCA is undertaken, it must be very clearly stated that the study differs from a more usual EPD or building LCA.
Rules from:

EN 15978

8.7.4 Scenarios for waste processing for reuse, recycling and energy recovery – Module C3

EN 15804

 6.3.8 Developing product level scenarios

ILCD

 Provisions: 7.4.3.7 Future processes and elementary flows
Guidance
 In every study, a baseline scenario reflecting current technology should be assessed. According to EN 15804 and EN 15978, it is important that scenarios for the use and EoL stages be based on today’s technologies. Scenario-based quantifications can be provided as accompanying information, and may be included in the assessment.To assess the impacts of future technological developments, separate scenario modelling may be carried out, if significant impacts on today’s decisions may be expected as a result of future technology shifts.Such developments could be, for example:

  • a shift in the energy mix over a building’s life cycle;
  • a shift in the energy efficiency of the building envelope;
  • new technologies to recycle construction waste.

Third-party forecast studies or – if this is within the focus of the research – the practitioner’s own forecast studies should be used as the basis for deriving assumptions for future technology shifts.

Any assumptions made, and the resulting modelling consequences, should undergo a third-party review.

Back to 5.2.  Goal and Scope

G-04 Comparative assertion for building or product LCA

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Aspect G-04 Comparative assertion for building or product LCA
Description

Comparative assertion is an environmental claim regarding the superiority or equivalence of one building product (or one building design) compared with a competing building product (or an alternative building design) that performs the same function. Usually, the comparison of alternative products, systems or buildings is the main goal of a comparative LCA study. Different aspects have to be taken into account to conduct a meaningful and robust comparative assertion. One of these is the functional equivalence between the systems under comparison (see the ‘functional equivalent’ aspect), but there are other aspects that need to be considered, such as the system boundary, the background database, the life cycle inventory, and the life cycle impact assessment methodology applied.

How can a comparative assertion be made in building LCA applications?

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 a comparative study, it must be ensured that the systems being compared are equivalent in function. According to ISO 14044 and ILCD, the same functional unit, system boundary, data quality requirements and allocation procedures have to be applied.

EN 15978 provides the practitioner with rules to be considered in the comparison of two buildings. The comparison also has to use the same environmental indicators, using those defined in the standard and in the ILCD Handbook.

The provisions of EN 15804 may be used under very specific conditions to compare cradle-to-grave product alternatives (cf. guidance).

 
Rules from:
 EN 15978:

Purpose of the assessment

EN 15978 states that it can be used for “assistance in a decision-making process, for example: comparisons of the environmental performance of different design options”.

EN 15804:

5.1 Objective of the PCR

EN 15804 states that the “declarations based on this standard are not comparative assertions.”

ISO 14040:

4.3 Key features of an LCA

5.2 Goal and scope definition

6 Reporting

7.2 Need for critical review

ISO 14044:

4.2.2 Goal of the study

4.2.3 Scope of the study

4.2.3.7 Comparison between systems

4.4.5 LCIA intended to be used in comparative assertions intended to be disclosed to the public

5.3 Further reporting requirements for comparative assertion intended to be disclosed to the public

ILCD:

6.10 Comparison between systems

6.10.3 Considered alternatives, the functional unit, and assumptions

6.10.4 Methodological, assumptions and data consistency

6.10.5 Data quality requirements

6.10.6 Identical parts of the compared systems

6.10.7 Scenarios in support of comparisons

6.10.8 Carbon footprint studies and other selected comparisons

 

Main provisions for all comparative studies (summary of the ILCD Handbook):

I) ISO 14044:2006 provisions for comparison assertions shall also be applied to non-assertive comparative studies.

II) All aspects of the goal and scope definition shall be addressed consistently especially for: LCI model, assumptions, data quality.

III) Uncertainty and accuracy calculation shall support this analysis.

IV) The completeness/cut-off (in%) shall be met for mass and energy, next to the overall environmental impact.

V) The excluded processes that are identical for all alternatives may be left out of all models.

VI) An LCIA shall be performed for LCA studies intended to support comparative studies (for public communication).

VII) If only one impact category (e.g. carbon footprint) is considered for those studies, it shall highlight that the comparison is not suitable to identify environmental preferable alternatives. This applies unless it is demonstrated that the two compared systems do not differ in other relevant environmental impacts to a degree that would change the main conclusions.

 

Main provisions for studies with similar functional equivalent (summary of the ILCD Handbook):

VIII) The compared systems shall have the same functional unit.

IX)  The study should include potentially environmentally better market relevant and available alternatives, as otherwise the study would be considered misleading.

X) The selected functional unit should reflect well-justified typical or average production/operation/use scenarios; it shall be agreed with the affected stakeholders.

XI) If the system needs to be replaced to meet the required duration of performance of the compared functional unit, the replacement should consider that potentially a newer system will replace the initially used model.

XII) For comparative micro-level studies (Situation A), each compared scenario shall be complemented with assumption scenarios of reasonably best and worst cases. Uncertainty calculation shall be performed.

XIII) For comparative meso/macro-level (situation B): the scenarios for each of the analysed alternatives shall apply the modelling guidance of situation A, except for processes affected by large-scale consequences of the analysed decision.

XIV) Involvement of interested parties in review.
Guidance
  

For building LCA applications, comparative assertions are typically conducted to choose among design alternatives.

The major focus of the LCA practitioner has to lie on defining two alternatives that are truly comparable. Therefore special attention should be directed to identifying all functions that a design alternative has. This may include technical functions, e.g. structural functions, and building physical functions, such as ensuring specified quality levels of the indoor environment, but also architectural and aesthetic functions. Therefore design alternatives should always be agreed within the planning team, including the architect, structural engineers, building physics and energy performance experts. If the functions of two design alternatives are not truly comparable, the planning team should identify additional solutions to ensure comparable features, and these should be included in the comparative LCA study.

Users who are not LCA experts typically use dedicated LCA tools for comparing their building’s design alternatives. Such tools may support the choice of adequate – comparable – design alternatives, and assist in conducting the LCA study, especially with regard to the comparability of background data, etc. (see below).

 

1) Practical guidance when comparing building design alternatives

Because design software contains built-in methodological decisions (functional unit, system boundaries, cut-off criteria, etc.), as well as built-in databases, it is generally important not only to apply generally uniform methodological decisions, but also to use the same software when comparing two building design alternatives.

Concerning the background database used for the comparative assertions, the user can look at the methodological report or user manual of the LCA software for buildings to check for consistency according to the ICLD handbook.

Useful information on the use of LCA in the design of buildings can be found in one of the deliverables of the LoRe-LCA European project (FP7), available online.

 

2) Comparative assertion for product LCA based on EN 15804 in E2B EI research projects

Under specific conditions, it may be possible to compare a regular product and an innovative product following EN 15804 provisions, if the product model is from cradle to grave. All the other provisions of EN 15804 should be applied, if necessary, to comply with the comparative assertion rules according to ILCD; otherwise use the ILCD provisions if no provisions exist in the EN 15804 standard.

G-05 Scope definition for building and product LCA

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Aspect G-05 Scope definition for building and product LCA
Description

According to [ISO 14040], [ISO 14044], and the ILCD Handbook, the scope definition of a study is the step where the main requirements related to methodology, quality, reporting and review in accordance with the goal of the study (i.e. based on the reasons for the study), the decision context, the intended applications, and the addressees of the results [ILCD 2010c] are stated. Examples of requirements include the function, functional unit and reference flow definitions, derivation of system boundaries, and cut-off criteria (completeness).

How can the practitioner set up the scope of the study? Are there special cases where the effort of scope definition can be simplified in regard to product or building LCAs?

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 scope definition of a study should be defined according to the context and the intended use of the assessment.

The documentation should also be in line with ISO 14044, EN 15978 and EN 15804.
Rules from:
 EN 15978:

6 Purpose of the assessment

7 Specification of the object of assessment

EN 15804:

6.2 Life cycle stages and their information modules to be included

6.3 Calculation rules for the LCA

ILCD:

6 Scope definition – what to analyse and how

Provisions 6.2.1 Consistency of methods, assumptions, and data

Provisions 6.2.2 Reproducibility

Provisions 6.3 Types of LCA deliverables and intended applications

Provisions 6.4 Function, functional unit, and reference flow

Provisions 6.5.4 LCI modelling provisions for situations A, B and C

Provisions 6.6 Deriving system boundaries and cut-off criteria (completeness)

Provisions 6.7 Preparing the basis for the impact assessment

Provisions 6.8.2 Technological representativeness

Provisions 6.8.3 Geographical representativeness

Provisions 6.8.4 Time-related representativeness

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

Provisions 6.10 Comparison between systems

Provisions 6.11 Identifying critical review needs

Provisions 6.12 Planning reporting

ISO 14044:

4.2 Goal and scope definition
Guidance

1) General guidance for product or building LCA studies

This step is closely linked to the goal definition. It is recommended that the LCA practitioner does not start from ‘zero’, but rather follows EN 15804 and EN 15978 if the scope definition within these standards is relevant for the context of the study. If not, it is recommended that the ILCD guidance on how to define the different aspects of the scope be used (see the rules from ILCD).

2) Practical guidance for product and building LCA studies according to the scope definition of EN 15804/EN 15978

The scope of the study defines the various contributors to include in the LCA study, such as the building products (Modules A, B, C, D), construction site (Module A5), energy consumption (Module B6), water consumption (Module B7), and transport of people (during the use phase).

The inclusion of any module depends on the goal definition, the stage of the project, and the LCA practitioner. Generally speaking, all the provisions for scope definition in EN 15804 and EN 15978 should be applied.

3) Predefined scope of product and building LCA studies according to EeBGuide study types

The definition of the scope of a study within the context of this guidance is also broadly predefined through the study type (screening, simplified or complete LCA). Provisions for aspects such as the completeness of the assessment (e.g. adapted calculation rules, system boundaries and cut-off-criteria), data representativeness and type (e.g. use of default values), documentation and communication help the definition of the scope. The reporting templates of the EeBGuide also help regarding documentation of the goal and scope of an LCA study.

G-06 (Buildings) / G-07 (Products) Functional equivalent

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Aspect G-06 (Buildings) / G-07 (Products) Functional equivalent
Description
 According to [EN 15643-1], the functional equivalent is a representation of the required and quantified functional and/or technical requirement for a building or an assembled system (part of works), which is used as a basis for comparison. Usually, assessments of individual objects form part of the decision-making process regarding, for instance, whether to build a new building or refurbish an existing building, or which are the most appropriate design options. In such cases comparison should be made only on the basis of functional equivalents. For this reason, in comparative studies between different systems/options, it is essential to define the functional equivalent.How should the functional equivalent be correctly defined?

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 At the building level, the functional equivalent should be defined with regard to EN 15978. it needs to include the building type, relevant technical and functional requirements, the pattern of use and the required service life. Other specific requirements or conditions may be relevant for inclusion in the information on the functional equivalent.The functional equivalent concept may be used at the sub-building level. EN 15804 defines the rules for the functional unit to ensure that the comparison is consistent (e.g. for assembled systems or components). In such cases the basis for the comparison is the entire building, ensuring that the same functional requirements are met.
Rules from:

EN 15978

 

 7.2 Functional equivalent

EN 15804

6.3.2. Functional unit

5.3 Comparability of EPD for building products

ILCD

 Provisions: 6.4 Function, functional unit, and reference flow

  • I) SHALL – Identify system or process
  • II) MAY – Photos, specifications
  • III) SHALL – Identify function(s) and functional unit(s)
  • IV) SHALL – Functional unit, details
    • IV.a) Function provided (what),
    • IV.b) in which quantity (how much),
    • IV.c) for what duration (how long),
    • IV.d) to what quality (in what way and how well is the function provided (what)
  • V) MAY – Obligatory and positioning properties
  • VI) SHALL – Measurement methods
  • VII) SHOULD – Alternatives and complements to the functional unit
    • VII.a) Materials and other application unspecific products
    • VII.b) Monofunctional processes
    • VII.c) Multifunctional processes
  • VII) SHOULD – Highly variable function
  • VII) SHALL – Comparative studies
Guidance
 In practice, a building has many different functions, and it is important to define correctly what is included in the functional equivalent. ISO and CEN standards dealing with the sustainability of buildings propose that the reference flow (which is conventionally called the ‘reference unit’) be differentiated from the functional unit (which is conventionally called the ‘functional equivalent’).In EN 15978, the reference unit (i.e. the expression of the results in terms of m² or number of people) is differentiated from the functional equivalent, which includes various aspects related to the characteristics of the building. At the building level, EN 15978 defines the functional equivalent, whereas at the product level, EN 15804 defines the functional unit.

  • Example of the functional equivalent of a building:

Type of building: Office building; 4000 m² net floor area

Use: net floor area heated or cooled to specified temperature level

Relevant technical and functional requirements: heated and cooled rooms with a temperature range between 20°C and 26°C; air change rate of 30m³/(h*person); lighting level 300 lux; see also specifications in national standards.

Pattern of use: 200 workers; working time from 07.00 am till 06.00 pm, 5 days per week, 48 weeks per year.

Design service life: 50 years

  • Example of the functional equivalent of an assembled system:

Type of system: Transparent solar thermal collector

Use: production of thermal energy in kWh per façade area in m². Relevant technical and functional requirements: U-value of 1.0 W/(m²K); function as shading device, reducing solar gains inside the building;

Design service life: 20 years

More information regarding the definition of the functional equivalent is linked to benchmarking criteria. Such concepts are much more developed in another European project (FP7) called ‘SuPerBuildings’. Interested practitioners can look at the online deliverable D5.2 ‘Benchmarking criteria for sustainable buildings in Europe’ on the website of the project.