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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.

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.
  • X) The selected functional unit should reflect well-justified typical or average production/operation/use scenarios.
  • XI) If the system needs to be replaced to meet the required duration of performance, 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.
  • XIII) For comparative meso/macro-level (situation B): the scenarios for each of the analysed alternatives shall apply the modelling guidance of situation A.
  • 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.

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 ILCD handbook.

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
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
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)
  • 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-06 Distinction between the declared unit and the functional unit

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Aspect G-06 Distinction between the declared unit and the functional unit

Description		 The functional unit represents the quantified performance of a product system for use as a reference unit for the LCA study. It is the unit of scale or reference on which the LCA results are based, and relates to the given function of the product. In other cases, the functional unit should be defined according to the future use of the building. A functional unit comprises a function, a quantity, a duration and a quality. The declared unit is used instead of a functional unit when the precise function of the product at the building level is not stated or known, or when the LCA does not cover a full life cycle. It is necessary to distinguish between these two concepts for product LCA, and to give operational guidance.
Related
study objective		 ☒ stand-alone LCA ☒ comparative assertion
Related
study phase		 ☒
goal and scope definition		 ☐
inventory analysis (LCI)		 ☐
impact assessment (LCIA)		 ☐
interpretation		 ☐
reporting
Relevant for
new buildings
existing buildings
construction products
screening LCA
simplified LCA
complete LCA

Provisions		 The practitioner should refer to EN 15804 and the ILCD Handbook for the correct definitions of the functional unit and the declared unit.

The declared unit should be used for raw materials that are not implemented directly in the building, and for non-application-specific products.

In other cases, the functional unit should be defined according to the future use of the building. A functional unit comprises a function, a quantity, a duration and a quality.

Under special conditions (e.g. if a building product has a rather large number of possible applications in a building), then the declared unit, as defined in EN 15804, may be more appropriate than the concept of the functional unit, as the functions provided by a construction product are often closely related to the way that the product is incorporated in the building, and this cannot be known at the point at which the product is assessed.

Rules from
EN 15804 6.3.1 Functional unit
6.3.2 Declared unit
ILCD Provisions: 6.4 Function, functional unit, and reference flowI) 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)

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
ISO 14044 4.2.3.2 Function and functional unit

Guidance		 1) Specific guidance for defining the declared unitThere are two cases when it is relevant to define a declared unit. The first is for raw materials (e.g. cement, gravel) for which a functional unit does not really make sense. The second is for products that can be used in a wide variety of different or simultaneous functions in the building or construction works: for example, a timber section might be used in upper floor construction, in a partition wall, in fencing or in joinery. For each of these functions, the wastage in construction and the service life of the timber might be different. Similarly, a concrete block could be used in either an internal or an external wall, and with thin joint or normal mortar; each of these options will impact differently on the thermal performance of the block in the building or construction works. In this second case, a declared unit is used, allowing the relevant data to be provided and aggregated at the building level, where the function of the product as installed can be considered over the building life. Examples of declared units include:

  • by item, e.g. 1 brick, 1 window (dimensions to be specified), 1 lighting-fitting, 1 radiator;
  • by mass, e.g. 1 kg of cement;
  • by length, e.g. 1 m of pipe, 1 m of a beam (dimensions must be specified);
  • by area, e.g. 1 m2 of wall elements, 1 m2 of roof elements (dimensions must be specified);
  • by volume, e.g. 1 m3 of timber, 1 m3 of ready-mixed concrete.

 

2) Specific guidance for defining the functional unit

For product LCA (e.g. EPD), the functional unit has to be closely defined with the company that commissions the LCA or EPD study.

For cradle-to-gate and cradle-to-site product LCA data, the function of the product within the building or construction works is uncertain, and it is therefore not easy to find a functional unit, which needs to include information on the required functional performance of the product within the building or construction works over the full life cycle. Nevertheless, during discussions on the development of CEN TC 350 the recommended route was to identify reasonable scenarios and include information for one or more of these scenarios. In defining such a scenario, much of the required information to describe a post-gate life cycle stage would originate from the building, and would be related to the product being studied.

The functional unit has a quantity (e.g. 1 m²), a duration (e.g. ‘maintaining the function over 50 years’) and a quality e.g. ‘”to ensure a thermal resistance of 2 m²/W.K’). It is closely connected to the definition of the relevant service life of the product (cf. the corresponding aspect).

For comparative purposes, different, simultaneously applying functions may be relevant. With the definition of the functional unit, all relevant functions should be covered.

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 it 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
    • 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)
  • 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		 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-08 Reference study period

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Aspect G-08 Reference study period

Description		 The reference study period (RSP) is defined as the time period for which the time-dependent characteristics of the object under assessment are analysed. The RSP determines the use phase of the assessed building or product. Maintenance, repair, replacement and refurbishment activities, as well as operational energy and water use, are highly sensitive to the RSP definition, and may contribute differently to the environmental impacts over the life cycle. Depending on the type of building or product to be assessed (e.g. existing or new), how should the reference study period be 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
not applicable for products
screening LCA
simplified LCA
complete LCA

Provisions		 The reference study period is generally not predefined, as there is a multitude of different conventional study periods for buildings all over Europe.
For comparison purposes, a reference study period of 50 years can be assumed as a baseline scenario.
For comparative assertions (comparison of two buildings or building types), the same reference study period has to be applied.

Rules from
EN 15978 7.3 Study reference period
EN 15804 6.3.3 Reference service life (RSL)

Guidance		 For building LCAs, common reference study periods for different European countries and purposes can be found in Annex A. To select an adequate reference study period, it is recommended that conventional values that may have been agreed for a specific country or building type be used, and that this number be used to ensure comparability of the results of the study.

In the EeBGuide, the value of 50 years for the baseline scenario is defined to provide consistency among studies that are set up in a comparative environment, such as research projects of the E2B Initiative. For other comparative studies, other reference study periods may be chosen (if relevant).

G-09 Energy-efficient product definition

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Aspect G-09 Energy-efficient product definition

Description		 What is an energy-efficient product, and how is it characterized?
Study
objective		 ☒ stand-alone LCA ☒ comparative assertion
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		 No specific definition is given. The LCA calculation rules must be appropriate for all building products.

Rules from:
EN 15804 The standard does not refer to energy-efficient products in particular, but the standard can be used to assess any product, component or element used in the building, including the assessment of building-integrated technical systems, as defined in 6.3.4.4.3.

6.3.4.4.3 B6–B7 use stage information modules related to the operation of the building:
B6 Energy use to operate building-integrated technical systems
CEN/TR 15615 Explanation of the general relationship between various European standards and the Energy Performance of Buildings Directive (EPBD) — Umbrella Document.

Guidance		 An energy-efficient building can consist of a whole range of building products and technical equipment; many of the usual ones will not influence energy consumption in use. Conversely, an ‘energy-efficient’ product can be one that increases the energy efficiency of the whole building. However, in the EeBGuide there is no existing differentiation between these different types of product in terms of assessing their life cycle impact, and product LCA data can be provided for building services equipment such as heating, air conditioning, transportation and lighting.

Energy-using products (EuP) are now covered alongside energy-related products in the EcoDesign Directive.

Energy-related products (ErP) are products such as windows and insulation, or products with thermal mass, which have an impact on the energy use of the building, but do not directly use energy themselves, and which are not part of the building-integrated technical system. These are also covered by the EcoDesign Directive.

In all cases, the particular use of the products in the building, and the design of the building, are key to understanding the performance of the product, and the operational performance of the building can only be assessed at the building level.

G-09 Object of assessment with regard to energy-efficient buildings

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Aspect G-09 Object of assessment with regard to energy-efficient buildings

Description		 Life cycle assessment is a flexible methodology that can be applied to all kinds of product or building. It is important to specify whether the LCA methodology has to be adapted in terms of system boundaries or cut-off rules when applying it to an energy-efficient building.How should the object of assessment be defined for energy-efficient buildings?
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		 Life cycle assessment is a flexible methodology that can be applied to all kinds of building, whatever their environmental performance or energy efficiency. For this reason, the definition of the object of assessment does not need to explicitly define specific levels of energy efficiency.
The current and forthcoming definitions of an energy-efficient building may, however, support an LCA approach (i.e. from cradle to grave), as opposed to a focused assessment that looks only at the environmental aspects linked to operational energy use.

Rules from
EN 15978 7. Specification of the object of assessment

Guidance		 The energy efficiency of buildings during their operational stage generally does not influence the definition of the object of assessment, as for a building LCA this generally refers to the building’s entire life cycle. For this purpose, it is recommended that national definitions across Europe be referred to, such as the German ‘passive houses’ or French ‘low energy buildings’ (BBC) and ‘positive energy buildings’ (BEPOS).The main information concerning the object of assessment should be considered in the functional equivalent; other, secondary information may also be reported regarding the scope of the study.

G-10 Definition of system boundaries for products

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Aspect G-10 Definition of system boundaries for products

Description		 The system boundaries of product LCA can be different, depending on the goal and scope of the study. If the goal is to create an EPD, then the practitioner is likely to follow the EN 15804 standards. But even for EPD, the system boundaries can vary, depending on the type of data: cradle to gate, cradle to gate with options, or cradle-to-grave. For LCA used in ecodesign, it may be relevant to include the recycling potentials of the products, thus extending the system boundary (a cradle-to-cradle approach) – that is, including Module D if the study complies with EN 15804. Generally speaking, the main issue for any product LCA is to define what to include, especially for the production stage.

How can the system boundaries be defined for product LCA?
Study
objective		 ☒ stand-alone LCA ☒ comparative assertion
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 practitioner should refer to the ILCD Handbook, or otherwise EN 15804, depending on the goal and scope of his study.

For LCA studies that are compliant with EN 15804, the practitioner should be aware that different system boundaries can be selected: cradle to gate, cradle to gate with options, or cradle to grave.

If the results are intended to be used for comparative assertions, then the rules used to define the system boundaries should follow the ILCD Handbook.

Rules from:
EN 15804 6.3.4 System boundaries
ILCD Provisions: 6.6 Deriving system boundaries and cut-off criteria (completeness)
“I) SHALL – Scope of LCA
II) SHALL – Processes within the system boundary
III) SHALL – Flows across the system boundary
IV) SHALL – System boundary diagram
V) SHALL – List of exclusions
VI) SHALL – part-system and system-system relationships
VII) SHALL – System-external off-setting
VIII) SHALL – Quantitative cut-off criteria”

Provisions: 7.2.3 Identifying processes in attributional modelling
“[…] I) SHALL – Identifying processes within the system boundary
   I.a) Start from central process
   I.b) Foreground system
   I.c) Background system
   I.d) Justify and document exclusion
II) SHALL – Initial processes description”

As an illustration for product LCA, the ILCD Handbook details the different life cycle stages to take into account and the different types of data. It has to be mentioned that the foreground data collection (based on e.g. measured data from company) takes place during the gate-to-gate stage (see below). For the other data (e.g. extraction processes), the data are likely to be based on background data.

Figure 11: Cradle-to-grave, cradle-to-gate and gate-to-gate datasets as parts of the complete life cycle

Guidance		 Different cases can be found in practice. For EPD data, rules from EN 15804 should be applied. These types of EPD system boundary can be found, depending on the goal and scope (e.g. for 1 kg of declared unit for cement, the system boundaries will be only up to the gate of the plant).

For E2B EI research projects, product LCA studies may be conducted for the full life cycle. The practitioner is likely to collect foreground data for the gate-to-gate stage among the project partners (e.g. a company involved in the project that would like to assess its new product), whereas for upstream or downstream processes the use of generic data may be sufficient. This last recommendation is also in line with EN 15804.

G-10 Definition of system boundaries for new buildings

Written on .

Aspect G-10 Definition of system boundaries for new buildings

Description		 A clear definition of the system boundaries is needed for improved understanding and interpretation of the LCA results, as well as to enable them to be used for comparative assertions (e.g. choice of design alternatives) or stand-alone LCA (e.g. benchmarking purposes).How should this system boundary be defined for new buildings?
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
not for existing buildings
not for construction products
screening LCA
simplified LCA
complete LCA

Provisions		 For a new building, the system boundary should include all stages of the life cycle. This includes all the upstream and downstream processes needed to establish and maintain the function(s) of the building, from the acquisition of raw materials to their disposal, or to the point where materials exit the system boundary, either during or at the end of the building life cycle.
For the inclusion of specific contributors (e.g. transport of people, water consumption etc.), the definition of the system boundaries is directly linked to the goal and scope definition (see the corresponding aspects).
EN 15978 gives clear rules for setting the system boundary of a building. These rules follow the ‘modularity principle’: that is, where processes influence the building’s environmental performance during its life cycle, they should be assigned to the module in the life cycle where they occur. The system boundary for new buildings should be defined according to EN 15978 and the different study types (screening, simplified or complete).

Rules from
EN 15978 7.4.2–7.4.6 boundaries
“The system boundary determines the unit processes that are taken into account for the object of assessment.
For a new building, the system boundary shall include the whole life cycle.”

Guidance		 The rules given in EN 15978 should be applied (see above). This covers the entire building life cycle as defined with regard to the study type used. The system boundaries include the entire building and its foundations, the building’s curtilage in the building’s site and connected exterior works. In addition, the study type’s definitions should be applied.