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Tag: Related study phase: Interpretation

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.

G-07 (Buildings) / G-08 (Products) Functional equivalent vs. functional unit vs. declared unit

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Aspect G-07 (Buildings) / G-08 (Products) Functional equivalent vs. functional unit vs. declared unit
Description
 ISO 14040, ISO 14044 and EN 15804 define a functional unit; EN 15804 also defines a declared unit. EN 15978 defines a functional equivalent.What are the differences, and when should which term be used?

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 ISO 14040 and 14044, as the basic LCA standards, define the ‘functional unit’ as the quantification of the performance of a product system, and specify that is used as the reference unit for the LCA and any comparative assertion.The term ‘functional equivalent’ is defined in EN 15978 as denoting the technical characteristics and functionalities of the building that is being assessed.The term ‘functional unit’, as defined in EN 15804, refers to the quantification of identified functions or performance characteristics of products. The function/performance characteristics of the product are defined at the building level. The functional unit is used primarily as the reference unit for the product LCA study.The term ‘declared unit’ is specific to product LCAs, as defined in EN 15804. It is used instead of the ‘functional unit’ if the specific function of a product at the building level is not known. EN 15804 states that the declared unit shall be used if an LCA study does not cover the entire life cycle (‘cradle to grave’), but only certain modules (e.g. only ‘cradle to gate’).The terms should be used in line with the definitions of the standards to allow for improved consistency of LCA studies within the construction sector.
Rules from:

EN 15978

 7.2 Functional equivalent

EN 15804

 5.3 Comparability of EPD for building products
6.3.1 Functional unit
6.3.2 Declared unit

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
o IV.a) Function provided (what),
o IV.b) in which quantity (how much),
o IV.c) for what duration (how long),
o 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
o VII.a) Materials and other application unspecific products
o VII.b) Monofunctional processes
o VII.c) Multifunctional processes
• VII) SHOULD – Highly variable function
• VII) SHALL – Comparative studies
Guidance
 The distinction between functional unit, declared unit and functional equivalent is specific to the European construction sector, as they are defined in the CEN standards. LCA practitioners who are not thoroughly familiar with these standards may find it difficult to understand the details of this differentiation.In general life cycle thinking, and for the practical purpose of conducting an LCA, the differences in definition and understanding are not critical to conducting an LCA study. All definitions essentially require the technical performance of the object of assessment to be quantified, and they require a comparative quantification for the case of comparative assertions and meaningful reference units, if the results of an LCA study are intended to be used elsewhere (e.g. the results of a product LCA to be used in a building LCA).For practical application, it is recommended that the terminology of the standards be used. It is essential for the success of an LCA study to define the relevant functions carefully, and to identify the appropriate reference unit, as this is the essential basis for any comparison and/or reuse of LCA data.

G-35 (Buildings) / G-33 (Products) Normalization of indicators

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Aspect G-35 (Buildings) / G-33 (Products) Normalization of indicators
Description
 According to the ILCD Handbook, the normalization step refers to the expression of indicators (LCIA, midpoints or endpoints) relative to a common reference by dividing the indicator results by the respective reference value. Different normalization factors can be applied in practice to help the interpretation of results in the building sector. How can this issue be considered within this guidance document?

related study objective

 ☒ stand-alone LCA ☒ comparative assertion

related study phase

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

relevant for
new buildings existing buildings building products screening LCA simplified LCA complete LCA
Provisions The normalization of indicators (which are the LCA results of products and buildings) should remain an optional stage, according to ISO 14044. However, in certain circumstances the normalization of results may be very helpful for the LCA practitioner and/or the decision-maker, and assist interpretation of the study results. 
Rules from:
 ILCD:
“Provisions: 6.7 Preparing the basis for the impact assessment […]
Normalisation and weighting: […]
XIII) MAY – Results interpretation: Normalisation and weighting are in addition optional steps under ISO 14044:2006 that are recommended to support the results interpretation (see part 6.3.6)”“
Provisions: 10.3 Three levels of reporting requirements […]IV) SHALL – Main report, with the following aspects […]

IV.e) Life cycle impact assessment results calculation, where applicable: […]

IV.e.vi) data and indicator results reached prior to any normalization, grouping or weighting shall be made available together with the normalized, grouped or weighted results.

IV.e) Life cycle interpretation: […]

IV.f.iv) full transparency in terms of value choices, rationales and expert judgements.
Guidance
 If the normalization step is considered for product or building LCA case studies it should be carried out in line with the ILCD Handbook. The assumptions should be documented as transparently as possible. Two types of normalization of results can be used in practice, answering two types of objective:1) Help to identify the most relevant indicators among the global set of indicators
In this case, the LCA results are scaled to a common geographical reference (e.g. at the European level, or in some national contexts) and for a given time period (e.g. 1 year). Generally speaking, normalization factors are available at the world, European and national levels per indicator per year. Doing this will enable the practitioner to identify the key indicators that are driven by the building sector, and in the specific study. It is a way to identify hotspots, and reduce for example the number of indicators from EN 15804/EN15978 or other indicators available in the ILCD Handbook (if relevant). The main issue is to be able to obtain the normalization factors for each indicator. The LCIA method usually provides normalization factors for the midpoint, such as the global warming potential (GWP), or endpoint indicators.For example, the CML 2002 method provides normalization factors for The Netherlands (1997), Western Europe (1995) and the world (1995). Other impact assessment methods, such as Eco-indicator 99, IMPACT 2002 and ReCiPe, also provide normalization values.

Some of these LCIA methods may be used in a building LCA in addition to the baseline indicators given in the EN 15978/EN 15804 standards. Previous European projects have provided the values for these normalization factors through their online deliverables.

Examples of normalization factors that can be used for the French context (mean impacts per person and per year) can be found below:

Mid-pointindicators Unit equiv-person /year Source
GWP kg eq-CO2 8680 CITEPA
AP kg eq-SO2 62.3 CITEPA
POCP kg eq-C2H4 19.7 CITEPA
EP kg eq-PO43- 38.1 IFEN
Other indicators Unit eq-person Source

Primary energy demand

 MJ 48 670 Observatoire de l’énergie

Water consumption

 m3 339 IFEN

radioactive waste

 dm3 0.51 ANDRA

Other wastes

 kg-eq 10400 ADEME

[Peuportier 2008]

Example of normalization factors that can be used for the European context can be found in the BRE Environmental Profiles Methodology.

A comprehensive set of normalization factors are described in detail in LoRe-LCA.

2) Comparison of LCA results with existing benchmarks

In the building sector, practitioners may be asked to comply with a set of targets for overall environmental performance. For example, an architect or a real estate manager may need to answer the following question: “Does the studied building perform well compared with current best and good practice?” In this particular case, the LCA results can be normalized to existing reference values to compare design alternatives with current practice.

Appendix B provides some first reference values for buildings for Germany and France.

G-36 (Buildings) / G-34 (Products) Weighting of indicators

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Aspect G-36 (Buildings) / G-34 (Products) Weighting of indicators
Description

According to the ILCD Handbook, the weighting step refers to an optional step of the ISO 14044 standard to support the interpretation of the profile as a fully aggregated result. Generally speaking, it is a subsequent step to the normalization of indicators (see aspect ‘normalization’), where each normalized indicator is multiplied by a specific weighting factor that is intended to reflect the relative importance of the various impact categories. Different weighting methods can be applied in practice to help the interpretation of results in the building sector.How can this issue be considered within this guidance document?

related study objective

 ☒ stand-alone LCA ☐ comparative assertion

related study phase

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

relevant for
new buildings existing buildings building products screening LCA simplified LCA complete LCA
Provisions The weighting of normalized indicators (which are the LCA results of products and buildings) remains an optional stage in this guidance document, in accordance with ISO 14044. However, in certain circumstances the weighting of indicators may be asked for by the decision-maker in order to ease the interpretation stage.
Rules from:
 EN 15978
11. Calculation of the environmental indicators“The standard does not present any methodology for the aggregation of the individual indicators.”

ILCD
“Provisions: 6.7 Preparing the basis for the impact assessment […]

Normalization and weighting: […]

XIII) MAY – Results interpretation: Normalisation and weighting are in addition optional steps under ISO 14044:2006 that are recommended to support the results interpretation (see part 6.3.6)”

“Provisions: 10.3 Three levels of reporting requirements […]

IV) SHALL – Main report, with the following aspects […]

IV.e) Life cycle impact assessment results calculation, where applicable: […]

IV.e.vi) data and indicator results reached prior to any normalization, grouping or weighting shall be made available together with the normalized, grouped or weighted results.

IV.e) Life cycle interpretation: […]

IV.f.iv) full transparency in terms of value choices, rationales and expert judgements
Guidance If weighting is chosen in the case study, this should be carried out with regard to the ILCD Handbook. The LCA practitioner should keep in mind that the weighting step in LCA is always a subjective step, which should be documented as transparently as possible. The LCA practitioner should not use weighting indicators in comparative assertions; and, whenever such indicators are used, should include a statement that ‘It should be recognized that there is no scientific basis for reducing LCA results to a single overall score or number.’.In practice, different approaches can be used to weight the indicators.– The first approaches are typically already included in final LCIA methods that are used by LCA practitioners. For example, weighting factors used in the LCIA methods (such as Eco-indicator 99, IMPACT 2002+ and ReCiPe) to go from midpoint to endpoint indicators (reflecting three areas of protection: human health, ecosystem and resources) may be based on different assumptions. For example, the developers of the Eco-indicator99 method, as well as ReCiPe, used the cultural perspective based on [Hofstetter 1998] to adapt the weighting factors, i.e. egalitarian, hierarchical and individualistic perspectives. Thus the midpoint categories, e.g. for the area of protection of human health (such as carcinogenic, respiratory effects, climate change, radiation and ozone depletion) are weighted differently according to each perspective.In the LCA of buildings, the practitioner should be cautious when using a damage indicator (if relevant for the study), as it is based on a series of assumptions.– The second approach uses expert panels. They are defined within an LCA study, and this should be done on a case-by-case basis. Different mechanisms can be used, such as setting the weighting factors by public policymakers or industry panels, broad stakeholder panels, expert panels, and so on [ILCD 2011a]. Examples of weighting in the LCA and construction sector can be found for the European context in the BRE Environmental Profiles Methodology, for example. Other weighting methods are also implemented in some building LCA tools, such as EcoEffect in Sweden.

A comprehensive list of weighting methods is described in detail in the LoRe-LCA project.

G-37 (Buildings) / G-35 (Products) Uncertainty analysis for comparative assertion

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Aspect G-37 (Buildings) / G-35 (Products) Uncertainty analysis for comparative assertion
Description
 An uncertainty analysis measures the variability of the data values: for example, a low variance leads to a high precision. Because of the long supply chain of building products and buildings as a whole, uncertainties are aggregated over the life cycle. Following [Huijbregts 2001], different types of uncertainty can be found in LCA: parameter uncertainty, model uncertainty, uncertainty due to choices, spatial variability, temporal variability, and variability between the sources and the objects. In general, an uncertainty analysis should not be confused with a data quality assessment. Similarly, an uncertainty analysis for a stand-alone LCA should not be confused with an uncertainty analysis for a comparative assertion: in the first case, all the various types of uncertainty mentioned above are present, whereas in the second case, not all of them are present. In a comparative assertion supporting  decision-making, it is important only to ensure that the LCA results remain robust, even if the absolute LCA is uncertain. This is especially true when the differences between two alternatives are less than 20% (a percentage often used by LCA practitioners as the level below which it cannot be stated that A is better than B).In this context, when and how should an uncertainty analysis be performed for comparative assertion 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 building products screening LCA simplified LCA complete LCA
Provisions An uncertainty analysis should be conducted for comparative assertions, and should be considered during the review process. It may be addressed by scenario analyses. For extended studies and in-depth discussions of uncertainty, the rules of the ILCD Handbook should be used. Also, the ongoing scientific discussion may be taken into consideration.
Rules from:
 ILCD
Provisions: 6.5.4 LCI modelling provisions for Situations A, B, and C
I.a.vi) Comparative studies, scenarios, uncertainty calculation:
“Uncertainty calculation shall be performed [for comparative studies], unless it has already been used to derive the reasonably best and worst case scenarios.”
“It is recommended to also perform and report such assumption scenarios and uncertainty calculations for non-comparative LCI and LCA studies.”
ANNEX E: Addressing Uncertainties in LCA16.3 Aggregating uncertainties over the life cycle

“Three main sources of uncertainty have been addressed: stochastic uncertainty, choice uncertainty, lack of knowledge of the studied system”

The ILCD Handbook also provides rules for not mixing the data quality aspects (falling under the term ‘accuracy’) with the other concept of ‘precision’ (or ‘uncertainty’). The graphical illustration in Figure 13 demonstrates this point.

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

I.a.vi) Comparative studies, scenarios, uncertainty calculation:

“Uncertainty calculation shall be performed [for comparative studies], unless it has already been used to derive the reasonably best and worst case scenarios. “

„It is recommended to also perform and report such assumption scenarios and uncertainty calculations for non-comparative LCI and LCA studies.“

ANNEX E: Addressing Uncertainties in LCA

16.3 Aggregating uncertainties over the life cycle

“Three main sources of uncertainty have been addressed: stochastic uncertainty, choice uncertainty, lack of knowledge of the studied system”

The ILCD Handbook also provides rules for not mixing the data quality aspects (falling under the term ‘accuracy’) with the other concept of ‘precision’ (or ‘uncertainty’). The graphical illustration in Figure 13 demonstrates this point.

Figure 15: Concept of precision
Guidance
 1) General guidance for product and building LCA studies
The main difference between LCA studies with comparative assertions and stand-alone LCA studies lies in the fact that some parameters or assumptions are the same in both cases (also called ‘conventional parameters’) so that the number of uncertainty sources may be considerably reduced. In this case, the practitioner should check only whether the LCA results remain robust even if the stand-alone LCA is uncertain on several parameters (e.g. epistemic such as like the linear relations between flows, processes and impacts; the life expectancy of a building etc.).Another problem for the LCA practitioner lies in selecting an adequate method to assess the uncertainty. Various quantitative methods exist in the literature to assess uncertainties, such as Monte Carlo simulation, for example. Other methods, such as fuzzy logic and statistical Bayesian methods, have been developed and applied to LCA by researchers.However, most of these sophisticated numerical methods are currently not implemented in user-friendly LCA software for buildings, so the practitioner typically cannot easily use them.Based on the state of the art of building LCA tools, the best way to conduct an uncertainty analysis is to carry out scenario analyses that assess the most significant parameters of the LCA study. It is then possible to check whether one alternative still remains better than another in the various scenario analyses.The main issue is to identify the parameters, and to define their ranges of variation.

More information on scenarios for LCA in construction can be found in a previous report of the LoRe-LCA European project (FP7), available online.

2) Specific guidance for advanced building LCA studies

LCA may often be used as a decision-making tool to support a comparison of alternatives, e.g. during the building design stage. In this case, it is relevant to have guidelines on how to assess whether the choice of the best alternative from an LCA point of view is robust when using uncertain aspects of the building LCA model. Different steps may be conducted for a detailed analysis:

– Identification and quantification of uncertainties for the key parameters

Uncertainty sources for building LCA studies can be found for the various contributors:

– building products: the LCA data of the building materials, the reference service life of the building products, the quantity take-off;

– energy consumption: the LCA data of the energy processes, value taken from thermal simulation software;

– water consumption: the LCA data of the water processes and treatment, the value determined with a calculation tool.

In addition, uncertainty can be found in the methodological choices made by the practitioner within the LCA software (data used, calculation rules etc.)

These sources of uncertainty may be assessed by defining distribution curves (e.g. log-normal, normal, triangle, Weibull) and then by deriving the relevant statistical parameters (e.g. the confidence interval at 95% or other statistical parameters if relevant).

This may provide relevant information for building LCA practitioners: for example, for a building product, the share of uncertainties linked to the reference service life (RSL), the LCA data or the quantity take-off (if these three sources of uncertainty are relevant for the study). A similar approach can be applied to the operational energy and water impact values.

– Propagation of uncertainties in building LCA results

For a building case study, the relative share of impacts driven by building products, operational energy or water use, etc. can be identified and the corresponding uncertainties assessed.

This approach allows building LCA results to be presented with e.g. a mean value and a standard deviation (as e.g. 10 kg eq-CO2/m²/yr ±1.4 for the GWP indicator of a building).

This is the first step in identifying the sources of uncertainty in building LCA results. If relevant, these uncertainties can be reduced, e.g. by collecting more accurate/precise data.

– Use of distribution curves for the key parameters in comparative assertions

The uncertainties for the key parameters can then be used in a comparative assertion for two building case studies (fulfilling the ISO 14044, ILCD and EeBGuide requirements, e.g. the two buildings shall have the same functional equivalent). This allows the practitioner to assess whether alternative A is better than B when taking uncertainties into account. If the standard deviations of alternatives A and B do not overlap, then the comparative LCA results can be considered robust. If they do overlap, it is not possible to state that A is better than B, given the corresponding uncertainties.

G-38 (Buildings) / G-36 (Products) Sensitivity analysis

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Aspect G-38 (Buildings) / G-36 (Products) Sensitivity analysis
Description
 According to the ILCD Handbook, the goal of a sensitivity analysis is to assess the reliability of the study by adjusting the main parameters to see how this affects the final results. It is part of the interpretation step, and is generally used together with complementary approaches, such as scenario or uncertainty analyses. Sensitivity analysis can be an effective way of predicting the outcome and the impact of a variable on the result. By conducting it, it is possible to make statements with regard to data quality and precision.Within this guidance document, is a sensitivity analysis necessary? How and when can it be conducted, depending on the study type

related study objective

 ☒ stand-alone LCA ☒ comparative assertion

related study phase

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

relevant for
new buildings existing buildings building products screening LCA simplified LCA complete LCA
Provisions A sensitivity analysis should be conducted for LCA studies that include comparative assertions. It may be used for a stand-alone LCA (if relevant to the goal and scope of the study).
Rules from:
 EN 15978:
10.3 Data quality
The significance of the data chosen for the building LCA shall be assessed by means of sensitivity analysis (more information in section 10.3 Data quality of the standard)

ILCD:
Provisions: 9.3.3 Sensitivity check (of accuracy and precision)
ILCD states that “it is useful to structure the sensitivity check along the LCA stages.” The sensitivity of results should be checked in order to improve the quality and the validity of the study. The main goals are:

– sensitivity to significant issues (e.g. LCI flows, LCIA factors, modelling choices and assumptions);

– improvement of robustness of sensitive issues data, parameters, methodological choices;

– report final achievements; potentially revise the goal and scope.
Guidance
 Sensitivity analysis can be considered as an alternative method for assessing the uncertainty in comparative assertions. It is very similar to scenario analysis, as the main focus is to set a range of variation for a given number of parameters of the LCA study.Sensitivity analysis can be conducted for a stand-alone LCA to assess the range of variation of the LCA results. More frequently, it is used to improve the robustness of decision-making. In comparative LCA studies it enables the user to assess whether alternative X remains better than alternative Y when subject to a modification of the LCA modelling parameters or methodological choices (e.g. burden allocated or not to a by-product).The different aspects to consider for the sensitivity analyses depend on the goal and scope of the study.

1) Guidance for building LCA studies

For example, the usual parameters for building LCA, such as the reference study period of the building (RSP), the end-of-life (EoL) scenarios, the transportation distances, the choice of data for building products, energy and water processes (generic, specific) can be submitted to a sensitivity analysis (if relevant to the goal and scope of the study, and if the LCA tool allows such an analysis). For more information about sensitivity analysis guidelines for building LCA, please consult the LoRe-LCA report ‘Methods and guidelines for sensitivity analysis, including results for analysis on case studies’, available online.

2) Guidance for product LCA studies

For product LCA, the sensitivity analysis can be conducted for the choice of data (e.g. generic vs. specific data for the foreground system), the EoL scenarios, the transportation distances for the upstream processes (e.g. raw materials supply) etc.