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Author: Anh-Migrate

2.2 Reference documents for the EeBGuide

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The EeBGuide refers to several sources that provide rules and guidance for LCA practitioners. The first such source is the original ISO standards on life cycle assessment, i.e. [ISO 14040] and [ISO 14044]. In addition, the ILCD Handbook provides extended guidance on LCA in general. The ILCD series of technical guidance documents for LCA have been developed to support LCA practitioners in the planning, performance and documentation of complete and detailed LCAs. The recommendations given in the handbook are in line with the requirements of ISO 14040 and ISO 14044. Other important sources of guidance for the LCA practitioner are [EN 15804] and [EN 15978], which define LCA of building products and buildings more specifically. These European standards were developed by the CEN technical committee on sustainability of construction works (CEN TC 350). Other reference documents considered for setting provisions and rules were the ISO standards on service life planning (the ISO 15686 series), and various scientific reports and articles.

2     Methodological approach of the EeBGuide.

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.

2.3.1 EeBGuide provisions for different goal definition: strictness vs. flexibility

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LCA has been developed as a flexible system that can be adjusted to answer different kinds of question [CALCAS 2009]. In this context, standardization is always a difficult task, as it is done under a specific goal definition (e.g. EN 15804 is developed for giving rules for EPD). According to [CALCAS 2009], standards contribute to the harmonization of terms and procedures that are needed for comparison (as practised by rating agencies or consumer agencies). Thus standardization is often not helpful for the optimization of specific processes. Individual concepts that address the specific problems and goals are often more appropriate for such cases.

The practitioner should be aware that for some key aspects, such as goal definition, following the ILCD Handbook may lead to provisions that are different from those in the EN 15804/EN 15978 standards. Hence it is very important to distinguish the different provisions found in the EeBGuide. Although some provisions can be used for all studies, others may be used only under the goals and scope of the EN 15804/EN 15978 standards. For example, most of the time provisions for product LCA are in line with EN 15804.

The EeBGuide has two related objectives when choosing provisions from both CEN TC 350 standards and the ILCD Handbook. First, it is structured in line with the EN 15804 and EN 15978 standards (Modules A, B, C and D), so the provisions (based either on ILCD or EeBGuide) provides consistent rules for implementation of the two standards in practice. This is the ‘rigid’ part of the EeBGuide, which enables it to be in line with more operational projects such as the SBA Common Metrics. Such a perspective is more likely to fall under the secondary audience, e.g. for EPD and building certification purposes (but not only these).

Second, it is structured according to the life cycle steps of the LCA framework. It clearly defines provisions for the different goals and scope of building and product LCA studies. Here, the intention is to detail the different definitions of goal and scope that may be found in practice, for example in comparing two innovative products in an E2B EI research project, or assessing the introduction of a new technology into the market by the use of consequential modelling. This is the ‘flexible’ part of the EeBGuide. Such a perspective is more likely to fall under the primary audience, as E2B EI projects (but not only these).

2     Methodological approach of the EeBGuide.

2.4 Use of three study types

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LCA studies can be undertaken to meet a multitude of different goals, and often different goals are addressed in one single study. Depending on its goals, the study will have a different scope and level of detail. Generally speaking, LCA is an iterative process, as illustrated in the ILCD Handbook (see Figure 6).

Figure 6: LCA as an iterative process [ILCD 2011a]

In the construction sector, LCA studies cannot be completed with the same level of detail as in other sectors. Users such as architects and design engineers require user-friendly tools that can be adapted to the specifics of a building project, and to their needs. An architect during an architectural competition may conduct a screening LCA for supporting his/her design alternative (first iteration in Figure 6), whereas at a more advanced stage of the building project a complete LCA may be required (third iteration in Figure 6). These different iterations will often not necessarily be performed by the same stakeholder. In each case the data, methodology and results need to be adapted to the goal of the study, and to the stakeholder’s requirements.

Within this guideline, three different LCA study types have been defined: screening, simplified and complete (see Table 5). Each LCA study for products (i.e. products, materials, components or services) or buildings can be conducted at these different levels of detail, depending on, for example, the goal and scope of the assessment, the experience of the practitioner (architect, LCA expert), the data availability, or the state of development of the product or building being assessed. These levels of detail have several implications for the following aspects:

–       Completeness of the assessment

  • System boundaries (e.g. selection of building components included, and inclusion of selected life cycle stages or information modules)
  • Calculation rules (e.g. for energy and water consumption)
  • Life cycle impact assessment (LCIA) (e.g. for number of indicators to be used)
  • Interpretation for building-level applications of the LCA results (e.g. comparability)

–       Data representativeness (e.g. use of specific or generic LCA data, input data based on estimations or on precise calculations)

–       Documentation of LCA results

–       Communication of LCA report and results

For building assessments, the aim of both screening and simplified LCAs is to simplify the completion of a building LCA study by the practitioners, for example, in the early design stages. Several aspects need to be adapted (e.g. data types and calculation rules) to streamline the LCA of buildings. For example, default values and adapted calculation rules can be used for estimating the impacts of the building components, water and energy consumption. It is also possible to adapt the system boundaries in screening and simplified LCA, for example by omitting details such as joints or individual services during the use stage.

In this guidance, as far as possible, for screening and simplified LCA the insignificance or irrelevance of a life cycle stage, or a contributor (e.g. deconstruction activities), or an indicator (e.g. ADP, GWP, POCP) should be justified by the scientific evidence for each aspect (e.g. by a comparison between a full building LCA study and a simplified one omitting one of these aspects). As far as possible, the EeBGuide supports this approach of justified, sound simplification, as shown in previous studies e.g. [Kellenberger 2009]. It enables the LCA methodology for the building sector to be streamlined, while maintaining the precision of the results as far as possible, and adapting the LCA methodology to the needs of the building stakeholders.

As a result, the EeBGuide provides mainly guidance on the data types (e.g. use of default values in early design stages) and calculation rules for both screening and simplified LCA. The final choice of omitting life cycle stages or LCIA indicators is left to the practitioner.

Note: However, it is strongly recommended that LCA studies be performed with more than one LCIA indicator, and covering several life cycle stages; the results of single-stage or single-indicator studies can be misleading, and the approach does not match life cycle thinking. Issues such as burden shifting can occur, but may not be detected, and it is the core objective of the LCA methodology to obtain a comprehensive view of the environmental performance of a technical system. As the EeBGuide is related primarily to energy-efficient buildings and products, the inclusion of at least PENRT (total use of non-renewable primary energy resources) and if relevant the GWP (global warming potential) and PERT (total use of renewable primary energy resources) is strongly recommended.

The complete LCA approach is proposed for the more advanced phases of a building project. In this case, precise calculation rules have to be followed, and comprehensive system boundaries have to be used in developing a complete LCA study.

The following section explains the different study types in more detail.

Focused assessment

The concept of life cycle assessment generally has two basic connotations:

If a practitioner concludes from the goal and scope of a study that the assessment should cover only selected life cycle stages or selected information modules, or that only one single indicator should be assessed, then the practitioner is free to do so. For example, aspects such as specific building components or services can be considered without requiring an in-depth analysis of the entire building. However, under these circumstances such a study cannot be referred to as ‘life cycle assessment’ within the context of this guidance, but should be denoted as a focused assessment.

It is strongly recommended that the calculation methods and applicable provisions given in this document be used for the elements selected for assessment, to ensure the minimum comparability for such studies.

Examples of focused assessment:

  • study focused mainly on operational energy use (B6), in order to show the results of different energy supply systems.
  • study for a facility management company, focusing on maintenance (B2), repair (B3, B4) and operational water use (B7).

2     Methodological approach of the EeBGuide.

2.4.1 Screening LCA

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Purpose

A screening LCA study may serve for an initial (quick) overview of the environmental impacts of a building or a product. The challenge is to adapt the LCA methodology and simplify the use of LCA at the early design stage. With a screening LCA, it is not possible to retrieve detailed results on the environmental performance of a building or a product, and comparative assertions according to ISO 14044 cannot be based on it. Comparisons can be made internally, but these comparisons should not be published. This type of study yields an estimate of the environmental performance, which can be helpful in the early stages of design (e.g. for an architect’s draft design0 in of a research project (e.g. to identify environmental hotspots that require an additional, in-depth assessment).

Completeness of assessment

A screening study would typically focus on the main contributors to the system under assessment, including (but not limited to) the input materials, water and energy use, and the transportation of users (if relevant). In screening LCA, to avoid misleading results, care is needed to ensure that omitted building products are not significant for the chosen environmental indicators. It is also important to use adapted calculation rules for screening LCA (e.g. the use of statistical data for assessing impacts of water consumption). More information on the calculation rules can be found in Table 5.

Cut-off rules, as specified in EN 15978 and EN 15804, and in the ILCD Handbook, may not apply to screening LCA studies for buildings or products. For example, in the early design stages not all the input raw materials and components are known in detail, which means that some of them are omitted. Rather than systematically neglect them, one option is to try to model these omitted processes using default values. Generally speaking, life cycle modules, inputs and services should be omitted only if their insignificance for the corresponding environmental indicator can be scientifically justified.

A screening study might focus on one single indicator or several, and most studies should include PENRT (total use of non-renewable primary energy resources) and if relevant the GWP (global warming potential) and PERT (total use of renewable primary energy resources). As a general rule, a set of between five and seven additional relevant core LCIA indicators can be used (see the corresponding aspect in section 5). They may be taken from either EN 15804 or EN 15978, and from additional indicators described in the ILCD Handbook (if relevant for the purpose of the study).

Data representativeness

In comparison with the other study types, a screening study is likely to be based on generic assumptions, according to the goal and scope of the study. For example, if the goal is to conduct an LCA study within a European project, then the use of generic assumptions for the EU context may be sufficient. However, if the goal is (as in most cases) to conduct an LCA study that is representative within a national context, then generic assumptions for the national context are appropriate. Five major areas related to the representativeness of data can be considered: geography, technology, age, time and precision. It is also important to ensure consistency within the data used.

Geography

The data used in a screening study should, as far as is practical, given the existing time and budget constraints, relate to the country from which the building or product originates, and in which it is built or produced. However, as this is not always possible, it is also acceptable to use assumptions from a neighbouring country (with a similar context), or average European data, or even average global data. In this case, the data used, and their limitations, should be highlighted in the documentation. These provisions do not apply to data on energy, water and waste treatment processes, as national data are preferable (e.g. electricity mix, natural gas) but, otherwise, European data can be used if relevant.

Technology

The data used should represent the technology used as closely as possible. For example, if different heating systems are to be assessed from a product or building perspective, or if a comparison of bearing structures from reinforced concrete against timber framing is intended, then the data should reflect an equivalent state-of-the-art technology.

Precision

Average environmental quantitative information on the building or product may be taken from generic LCA data, or from default values for major components. For other sources of impacts related to the operational energy and water, and to 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 the goal and scope
  • Life cycle stages included
  • Main input materials/items included, as well as processes for energy, water etc.
  • Overview of calculation rules, and comment on degree of approximation/uncertainties
  • Impact categories considered
  • Life cycle impact results and interpretation (conclusions)
  • Statement regarding consistency
  • Results

Communication of LCA report and results

Screening LCAs are for internal communication purposes only (e.g. during an architectural competition), not public comparative purposes. A statement about the uncertainty of the results due to the screening process must be included.

Examples of screening LCAs:

  • Building LCA study to identify environmental optimization potentials in the early design stages (for an architect or stakeholder, helping to improve the building design).
  • Supporting documentation for an architectural competition.
  • Comparison of a, innovative new product and an existing one (e.g. within a company).

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.

2.4.3 Complete LCA

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Purpose

A complete LCA study reflects the regular approach to LCA, following ISO 14040/14044. It meets the requirements of ISO 14044, and reflects the basis for comparative assertions and other external communication. It covers the entire building’s or product’s life cycle, and yields a comprehensive view of the environmental performance of the building or product. This type of study serves to identify environmental hotspots, and gives assurance concerning the contribution to environmental impacts from individual life cycle stages, building elements, products, components or services. It is recommended that this type of study be used to provide relevant decision support for the detailed design of a building.

Completeness of assessment

Complete LCAs should ideally consider the whole life cycle – that is, from cradle to grave (Module A1 to C4), as well as Module D (if relevant to the goal and scope of the study) – and should consider a comprehensive set of environmental impact categories taken from both EN 15804/EN 15978 and additional indicators described in the ILCD Handbook (if relevant for the purpose of the study).

When a complete LCA is undertaken, to understand the impact of a building over its full life cycle (cradle to grave), care must be taken to review the relevant scenarios that may be applicable to the use phase. Very different assumptions on service life, energy in use, patterns of use, disposal and recycling may be appropriate, leading to more than one scenario evaluation to reflect different practice and impacts. In addition, hundreds of different products are used in the construction of buildings, and it may be very challenging to obtain quantitative environmental information about their production, transportation, service life, recyclability, etc.

The assessment should accurately represent the quantification of the building and scenarios used. In EN 15804 and EN 15978 the following criteria for exclusion of inputs and outputs are defined:

  • “1% of renewable and non-renewable primary energy usage and
  • 1% of the total mass input of that unit process.
  • The total of neglected input flows per module, e.g. per Module A, B, C or D shall be a maximum of 5% of energy usage and mass.”

In the ILCD Handbook these criteria for exclusion of inputs and outputs are defined more strictly as an iterative approach to get as close to 100% as possible.

For a complete LCA the recommendations of the ILCD Handbook should be followed. The definition of the cut-off rules mentioned in EN 15804 and EN 15978 could possibly generate misleading results in specific cases (e.g. in studies with a focus on toxicity). Therefore the EeBGuide stresses that the cut-off rules have to be defined in accordance with the goal and scope of the study.

Whenever LCI data are available for describing, for example, a raw material (for a product LCA) or LCA or EPD data on a building product (for a building LCA), it should be taken into account in the study. Cut-off rules aim only at easing the process of doing an LCA, for example by neglecting plastic bags for an upstream raw material (for a product LCA), or for neglecting minor components in a building (but ensuring that the simplification does not bias the results). For more information, see the cut-off aspect in the guidance document.

In practice, LCA practitioners may face significant challenges to meet these requirements for buildings, as extensive documentation of the building products used in a construction project is required. To-day, such extensive documentation is not generally state-of-the-art for typical construction projects. Experience shows that the situation may be improved significantly if the project developer/investor, the architect and the construction company cooperate from the early design stages onwards, to establish extensive and automated documentation systems for the construction materials and specific products used.

Data representativeness

For a complete LCA, stricter requirements must be considered to ensure an appropriate level of data representativeness. ISO 14044 provides a full list of the rules in the following areas:

  • Time-related coverage: the period over which the data should be collected, and how recent this data must be.
  • Geographical coverage: the geographical area from which data should be collected in order to meet the requirements of the goal and scope of the study.
  • Technology coverage: the LCI data should reflect the technology applicable to the product, component, element or part of the building under study.
  • Precision: a measure of the variability of the data values.
  • Completeness: the percentage of flow that is measured or estimated.
  • Representativeness: a qualitative assessment of the degree to which the dataset reflects the true population of interest (i.e. geographical coverage, time period and technology coverage).
  • Reproducibility: a qualitative assessment of the extent to which information about the methodology and data values would allow an independent practitioner to reproduce the results reported in the study.
  • Sources of the data.
  • Uncertainty of the information (e.g. data, models and assumptions).

Geography

LCI data should represent the country in which the material is sold, or in which the process or activity is taking place (wherever it occurs in the life cycle).

Technology

LCI data should reflect the technology applicable to the product, component, element or part of the building under study.

Precision

Specific descriptions of the products (component, element, or part of the building) should be used. Specific EPDs may be used (e.g. if the chosen indicators are covered by the EN 15804/EN 15978 list of indicators), as well as specific 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 should be made of whether the study methodology is applied uniformly to the various components of the analysis.

Documentation

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

  • Definition of the goal and scope
  • Life cycle stages included, and a clear definition of the system boundary
  • Input materials/items included, and any excluded, with justification (cut-off rules)
  • Impact categories considered (with justification)
  • Assumptions and comment on degree of approximation/uncertainties
  • Main assumptions and limitations
  • Life cycle impact results, broken down by life cycle stage and module
  • Statement on consistency
  • Interpretation and conclusions
  • Review statement

Communication of LCA report and results

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

Most complete LCAs will be conducted for producing LCA studies of buildings for the detailed design and assessment stages. If a complete LCA is to be used to provide a comparative assertion intended to be disclosed to the public, then there are further requirements set within ISO 14044, and the LCA will require critical review by a panel of interested parties.

Examples of a complete LCA:

  • Comparative LCA study of different buildings or building designs.
  • Selection of the most appropriate construction strategy for the refurbishment of a building’s envelope.
  • Detailed identification of the environmental hotspots of a product or a building.

2     Methodological approach of the EeBGuide.

2.5 Use of a baseline scenario

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Deviations in the final results of product and building LCAs may arise from the use of different sets of parameter values, depending on the goal and scope and according to the study type definitions (see previous section). This can be an issue when comparing the outcomes of research projects. As a result, the methodological approach for the guidance document includes the use of a baseline scenario. A common set of parameter values for all European research projects is highly useful for supporting and providing consistency in comparisons.

The EeBGuide suggests some parameters some as a baseline scenario (see Table 1). The use of these parameters is suggested, but is not mandatory for all LCA studies conducted either within E2B EI projects or externally (LCA tool development, certification schemes). Even within E2B EI projects, such a reduced list of parameters does not guarantee comparable results among different project results. Differences may occur from, for example, different choices of LCA data, or from different modelling approaches for the energy consumption assessment, as the EeBGuide cannot recommend the choice of, say, only one LCA database or one dynamic thermal simulation software package to be used in E2B EI research projects. The provisions and guidance included in the guide help overcome this issue, but they cannot ensure total comparability of all LCA studies performed in the various E2B EI projects. In addition, the baseline scenario is goal and scope dependent, and a set of parameter values cannot be proposed for all situations (e.g. stand-alone LCAs, comparative assertions).

 

Table 1: Selected standard set of parameter values for the baseline scenario

Parameter

Standard parameter value

Reference study period

50 years

LCA data for electricity consumption

European (annual) average datasets or national (annual) average data if more relevant for the study

Future technological developments (Modules B, C and D)

No future technological developments are assessed; currently used technology is the basis for the assessment

Average transportation distance in Europe for Module A4

300 km

Carbon storage

Carbon sequestration is not considered explicitly

End-of-life scenarios (Modules C and D)

Use contemporary percentages for each building material (do not use a probabilistic scenario)

 

If comparable results are sought between different E2B EI research projects, practitioners should select a standard set of parameter values for their studies that is as uniform as possible. This includes the parameters listed above (adaptations are possible, if relevant), and the definition of the system boundaries for the building elements, operational energy and water use.

Note: the parameter choices given in Table 1 are neither ‘correct’ nor scientifically proven to be the best values, but rather represent a set of definitions to form a common basis for different studies. Therefore, in general, no scientific proof is given for these values. If available, reference to a third-party source is provided. If not, the values or decisions for these parameters have been defined by this guidance’s authors.

Additional in-depth work is needed to determine a comprehensive set of parameter values for the baseline scenario for product or building LCA studies with specific goals and scopes. The EeBGuide partners believe that this is the only way to move towards comparable results among different LCA studies. To that end, contributions from projects such as SBA Common Metrics, Superbuildings and OpenHouse can be very helpful.

3.1 Structure of the guidance document

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This guidance document is structured in two parts: one dedicated to the LCA of building products, and the other to the LCA of buildings. Both documents contain a general section covering the implementation of study types, and guidance on how to conduct LCA studies in general. Within the general section, and within sections for the various life cycle modules, important aspects that require consideration when conducting an LCA study are noted, along with provisions and guidance on these aspects. Some of these aspects are common to products and buildings, but others are specific to either products or buildings.

Within the context of this document, the word ‘building product’ is used for everything that is not a whole building (e.g. building parts, elements, components, products, services).

Also, in this guidance no specific definition is given for an energy-efficient building. Generally speaking, it corresponds to the current best practice in Europe, reflected by energy-efficient labels such as Passivhaus in Germany, BBC-Effinergie in France, or the new thermal regulation (e.g. RT 2012 in France). As a result, the aspects defined in EeBGuide apply for all kinds of energy-efficient building in Europe.

Each document is structured according to the life cycle stages of a building from cradle to grave, as given in the EN 15804 and EN 15978 standards, and shown in Table 2. The conventional terms used in EN 15804 and EN 15978 reflect one possible way to depict the building life cycle. For example, the standard chose to exclude Module D (accounting for the recycling potential) from the system boundary of a building. This should be interpreted only as a conventional term. Under the specific goal and scope of a study (e.g. design for recycling LCA studies), the use of Module D or other modelling scope may be needed if relevant. However, the EeBGuide partners believe that it makes sense to follow the conventional terms in EN 15804 and EN 15978 for describing the life cycle of a building or a product, in order not to reinvent or redefine such aspects.

 

Table 2: Modular information for the different stages of the building assessment, according to EN 15978 and EN 15804

Building assessment information
Life cycle stage modules Description
Building life cycle information PRODUCT stage A1 Raw material supply
A2 Transport
A3 Manufacturing
CONSTRUCTION PROCESS stage A4 Transport
A5 Construction, installation processes-installation-process
USE stage B1 Use
B2 Maintenance
B3 Repair
B4 Replacement
B5 Refurbishment
B6 Operational energy use
B7 Operational water use
End-of-life stage C1 Deconstruction, demolition
C2 Transport
C3 Waste processing
C4 Disposal
Supplementary information Benefits and loads beyond the system boundary D Reuse, recovery and/or recycling potential

 

The guidance document uses a substructure for the general aspects common to both levels (products and buildings) that corresponds to the usual LCA framework – goal and scope definition, life cycle inventory analysis (LCI), life cycle impact assessment (LCIA), interpretation, reporting – according to the ISO 14040 and ISO 14044 standards as well as the ILCD Handbook. This structure helps experienced users who are not directly familiar with the EN 15804/EN 15978 structure to navigate quickly through the document.

For each important aspect defined in the EeBGuide (see section 2.1), a template reporting the relevant information is provided. It includes the description of the aspect, the rules from EN 15804/EN 15978, the ILCD Handbook and other sources (if relevant), and the main provisions and guidance. Table 3 presents the different parts of the template.

Table 3: Example of the template document for each important aspect in the EeBGuide

Overview of the template for reporting each important aspect
Name of the aspect
Description of the aspect
Related study objective – stand-alone LCA
– comparative assertion
Related study phase – goal and scope definition
– life cycle inventory (LCI) analysis
–life cycle impact assessment (LCIA)
– interpretation
– reporting
Relevant for (study type) – screening LCA
– simplified LCA
– complete LCA
Relevant for (product/building) – new buildings
– existing buildings
– building products
Provisions
Rules from – EN 15978
– EN 15804
– ILCD Handbook
– ISO 14044
Guidance

For improved orientation, icons are used for assisting navigation through the document; these are listed in Table 4.

Table 4: Description of the icons used

Description of icons
Icon Meaning
  Description of the aspect:
The aspect of concern is described, and the critical points are highlighted; typical questions within this context may be provided.
  Provision on the aspect:
How to address the aspect of concern is given here.
  Reference to standards or reference document:
Further references to standards such as ISO 14040, ISO 14044, EN 15978 or EN 15804 as well as the ILCD Handbook are provided.
  Guidance on the aspect:
Guidance is given on aspects for which there is no single solution, or where additional explanations are helpful.
  General:
Aspects that do not relate to a single life cycle stage, but cover several stages or are independent of individual life cycle stages, are grouped in the ‘General’ section.
  Life cycle stage A according to CEN TC 350 (EN 15804 and EN 15978):
Aspects that relate to life cycle stage A (product and construction) are grouped here.
  Life cycle stage B according to CEN TC 350 (EN 15804 and EN 15978):
Aspects that relate to life cycle stage B (use) are grouped here.
  Life cycle stage C according to CEN TC 350 (EN 15804 and EN 15978):
Aspects that relate to life cycle stage C (end of life) are grouped here.
  Module D according to CEN TC 350 (EN 15804 and EN 15978):
Aspects that relate to issues beyond the life cycle studied (benefits and loads beyond the system boundaries) are grouped here.
  New buildings:
Aspects that relate to new buildings are mentioned here.
  Existing buildings:
Aspects that relate to existing buildings are mentioned here.
  Products:
Aspects that relate to products, materials, components and services are mentioned here.
  Screening:
Aspects are sorted by the study type that they apply to. This icon symbolizes whether an aspect is important for a screening LCA (see Table 5 for the definition of ‘screening’).
  Simplified:
Aspects are sorted by the study type that they apply to. This icon symbolizes whether an aspect is important for a simplified LCA (see Table 5 for the definition of ‘simplified’).
  Complete:
Aspects are sorted by the study type that they apply to. This icon symbolizes whether an aspect is important for a complete LCA (see Table 5 for the definition of ‘complete’).
  Applicable:
If the icon has a black background, the aspect is relevant for that scope (e.g. the aspect is relevant for new buildings).
  Can be applied:
If the icon has a grey background, the definition can be relevant for that aspect (e.g. the aspect is applicable to existing buildings, but if needed can also be applied to new buildings).
  Not applicable:
If the icon has a grey background and is crossed, the definition is not relevant for that aspect (e.g. aspect does not concern new buildings).

 

Every aspect consists of four parts. First it is briefly described, and the main issue is explained. Then, wherever possible, a provision is given for the issue relating to the aspect. This refers mainly to the European standards (EN 15978, EN 15804) or the ILCD Handbook. This provision is mandatory for European research projects, but if applied in other contexts, it provision can serve as guidance or an information source. Then links to further literature are provided for every aspect, and finally operational guidance is given for every problematic aspect.

3     How to use this guidance document

3.1.1 Implementation of the study type definitions

Written on .

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