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Tag: Study type: Screening LCA

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-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 construction 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 it is characterized?

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 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 build-ings

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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.

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 Life cycle assessment is a flexible methodology that can be applied to all kind 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 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 be also 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?

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 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

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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 existing buildings 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.

G-11 Definition of system boundaries for existing buildings

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Aspect G-11 Definition of system boundaries for existing buildings
Description
 A clear definition of the system boundaries is needed to understand and interpret the LCA results better, as well as to use them for comparative assertions (e.g. choice of design alternatives) or stand-alone LCA (e.g. for benchmarking purposes). How should this system boundary be defined in the case of existing 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 construction products screening LCA simplified LCA complete LCA
Provisions For an existing building, the system boundary should include all stages representing the remaining service life and the end-of-life stage of the building.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.
Rules from:

EN 15978

 7.4.2 Boundary of the product stage (Modules A1 to A3)
7.4.3 Boundaries of the construction process stage (Modules A4 and A5)
7.4.4 Boundaries of the use stage (Modules B1 – B7)
7.4.5 Boundary of the end-of-life stage (Modules C1-C4)
7.4.6 Boundary for the benefits and loads beyond the system boundary (Module D)
The assessment should concern the building and its site. For existing buildings, the main issues are the use stage (B2 to B7) and the end-of-life stage. The system boundary should also include the production and transportation of any component and ancillary products used for maintenance (including cleaning) and transportation of any wastage from maintenance processes and the end-of-life processes.
Guidance
 The rules given in EN 15978 should be applied (see above). The LCA of an existing building can address different goals: for example, to compare different refurbishment scenarios and the current state of the building, or to compare a refurbishment scenario with an operation of demolition/new construction.For an existing building, five possible goals may be considered:

  • Scenario 1: Comparison of a rehabilitation operation with an operation of demolition/new construction.
  • Scenario 2: Comparison of a rehabilitation operation with no rehabilitation.
  • Scenario 3: Comparison of a rehabilitation operation with a reference rehabilitation operation.
  • Scenario 4: Evaluation of the absolute performance of an existing building without modification until demolition.
  • Scenario 5: Evaluation of the absolute performance of a rehabilitation operation.

Thus four different types of operation may be identified:

  • rehabilitation;
  • reference rehabilitation;
  • complete demolition and new construction;
  • maintenance of an existing building (maintaining performance during a given period).

A rehabilitation operation consists of a deconstruction operation (removal of products to change) and a reconstruction operation (adding new products to replace discarded ones). Reference rehabilitation is a generic rehabilitation that implies the use of standard construction materials, designs and processes. It is to be used for comparison purpose with regard to a specific rehabilitation scenario.

Defining the boundaries of the study implies selecting the items or contributors to the environmental impacts relevant to each use. The following contributors should be considered:

  • new building products (those of a new construction after demolition, or those that replace products discarded during rehabilitation);
  • products discarded during the operation;
  • products not discarded during the operation;
  • energy consumption of the building before the operation;
  • energy consumption after the operation;
  • water consumption of the building before the operation;
  • water consumption after the operation;
  • demolition operations;
  • deconstruction operations (discarding of products to be replaced);
  • reconstruction operations (replacement of discarded products);
  • new construction operations.

G-13 (Buildings) / G-12 (Products) Infrastructure machinery and capital equipment for material production, energy, water, waste and transport for screening and simplified LCA

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Aspect G-13 (Buildings) / G-12 (Products) Infrastructure machinery and capital equipment for material production, energy, water, waste and transport for screening and simplified LCA
Description
 Different LCA databases and datasets with different boundaries are available. These databases apply different rules for including or excluding infrastructure in LCA datasets (e.g. owing to database policy or cut-off-rules). Infrastructure, especially related to processes that have a high impact for other datasets (e.g. the production of electricity), can have an environmental impact that should not necessarily be neglected using cut-off rules. The infrastructure covered here comprises not only the capital equipment and machinery (the factories, equipment and machines) that are used to extract and process materials and manufacture products, but also the infrastructure for energy, water, waste and transport processes. Current practices show that the datasets from the various databases do not have the same system boundaries; sometimes infrastructure is included, and sometimes it is excluded.When and how should infrastructure, etc. related to material production capital goods, energy production, waste and transportation be excluded or included?

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 inclusion or exclusion of infrastructure is especially relevant for background data. In general, infrastructure, machinery and capital equipment should not be excluded systematically, but cut-off criteria should be considered depending on the impact categories.In common LCA practice, the LCA practitioner does not have an influence on the database modelling, or on the decision whether or not to include infrastructure in datasets. As a result, this depends directly on which background data to use. Hence, no provision is given on the subject of the general inclusion or exclusion of infrastructure etc. as, owing to restricted data availability, practitioners typically are not free to decide this matter in terms of databases or consistent datasets. For the inclusion or exclusion of infrastructure in the foreground system, the following provisions should be applied:For screening and simplified LCA, capital equipment and machinery may be omitted, owing to the application of provisions from EN 15804 and the corresponding cut-off rules. Examples for cases where these points are important are mentioned in the guidance section below.
Rules from:

EN 15978

 

 7.4.3 Boundaries of the construction process stage (Modules A4 – A5)7.4.3.1 General

7.4.3.2 Boundary of the transport to and from site (Module A4)

ILCD

 6.6.2 Qualitative definition of system boundaries
Systematic exclusion of activity types. ILCD states that “a systematic exclusion of e.g. transport, infrastructures, services, administration activities, etc. is not appropriate unless necessary according to the specific goal of the LCI/LCA study (e.g. if the quantitative relevance of such activity types is to be analysed, the system would be modeled twice, once with and once without them).”
Guidance
 The infrastructure, machinery and capital goods covered here are the capital equipment and machinery (the factories, equipment and machines) that are used to extract and process materials and manufacture products, and also the infrastructure for energy, water, waste and transport processes.According to the ILCD Handbook, a systematic exclusion of e.g. transport, infrastructure, services, administration activities, etc. is not appropriate unless necessary according to the specific goal of the LCI/LCA study. In principle, all quantitatively relevant activities that can be attributed to a system should be included in the system boundaries unless they are quantitatively irrelevant, applying the cut-off criteria.If the practitioner is in the position to (or needs to) collect foreground data on the production of materials or the treatment of waste, then the principle of focusing on the collection of important data (in terms of LCA results) should prevail. To this end, the predefined cut-off rules should be applied.In common LCA practice, however, background datasets are typically accepted as they are. To improve the consistency of a study, it is strongly advised that data from methodologically consistent databases be used. This then means that the consideration of infrastructure is generally consistent within the database. However, the practitioner should check, depending on the goal and scope of the study, whether  the treatment of infrastructure processes in the background data is relevant.Guidance related to cut-off rules should be used for infrastructure as part of the foreground model (i.e. the infrastructure that is directly included by the practitioner). The relevance of processes and inputs depends on the impact categories assessed. As a consequence, the inclusion or exclusion of infrastructure, etc. has to be evaluated with care.From an energy or global warming point of view, it may be possible to leave out the infrastructure related to the production of materials, as previous studies have shown that it represents less than 5% of the impact [Frischknecht 2007]. In other cases, capital equipment and machinery are important, e.g. wind power or water power.The normal assumption is that capital equipment and machinery for a manufacturing process are not significant, and are not considered in LCA. They may potentially be relevant if production output is very small, or the capital equipment has a very short lifespan, or the product has an extremely low impact. This could be reviewed initially by considering the importance of the annualized capital costs relative to the production costs, bearing in mind that environmental impacts are not discounted over time in the way financial costs are. If considered potentially important, the likely service life (length of useful service) for buildings, equipment and machinery would need to be reviewed so that the amount of materials used per annum of production could be considered, and compared with the cut-off criterion of 1% of total mass of inputs for the same period.For renewable energy generation as an energy process, e.g. energy from wind turbines or photovoltaic (PV) cells, the main impact is purely capital equipment, i.e. the manufacture of the turbine and infrastructure or the PV cells. In these instances, the energy processes should include capital equipment.In general it would be good practice to provide information in the background report on the inclusion or exclusion of infrastructure within any secondary datasets used, and its significance if included.

This aspect may need to be revised in a future version of the EeBGuide if additional impact categories such as land use or human toxicity and ecotoxicity are assessed (as mandatory indicators).

G-15 (Buildings) / G-14 (Products) Transport of goods in LCA studies

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Aspect G-15 (Buildings) / G-14 (Products) Transport of goods in LCA studies
Description
 With globalized supply chains, logistic processes occur throughout the life cycle of every product. The most important ones are transport processes, where several possibilities exist for the activity of carrying goods (e.g. by truck, ship or airplane) for the various life cycle stages, e.g. raw materials supply, manufacturing, on-site implementation, end of life. The environmental impacts connected with transport processes depend on several factors, e.g. the transport distance, the load factor or the empty return.How should the transport of goods be considered?

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 Generally speaking, in all LCA studies of a product or a building, transportation processes should be included for every life cycle stage: raw materials supply, manufacturing, transportation to the site, use, and end of life.The EeBGuide provisions are adapted depending on the study types and the corresponding life cycle stages. For screening and simplified LCA studies, transport to the building site and transport to end-of-life facilities are optional, owing to their potentially minor relevance, whereas they should be included for complete LCA. If they are included, the results should be documented separately.The provisions for a specific life cycle stage (e.g. Module A4) supersede the general provision provided here. The practitioner should refer to the provisions for the corresponding aspects: ‘Transport of raw materials to the manufacturer’, ‘Transport of products to the construction site – screening and simplified LCA’, ‘Transport of products to the construction site – complete LCA’, ‘Transport of wastes to landfill, incineration and recycling facilities’.
Other kinds of transport of goods not directly related to a building product may be taken into account for building LCA studies if they are relevant for the goal and scope of the study. If they are included, included, the practitioner should refer to the provisions for the corresponding aspects: ‘Transport of construction machinery to the building site – screening and simplified LCA’,
‘Transport of construction machinery to the building site – complete LCA’.
Rules  from:

EN 15978

 In EN 15978, the conventional life cycle stages take into account the related transportation processes that occur during the production, construction, use and end-of-life phases.
7.4.3.2 Boundary of the transport to and from site (Module A4)
7.4.3.3 Boundary of the construction installation process (Module A5)
7.4.4 Boundaries of the use stage (Modules B1–B7)
7.4.5 Boundary of the end-of-life stage (Modules C1–C4)
7.4.6 Boundary for the benefits and loads beyond the system boundary (Module D)

=> Transport of goods, wastes, construction equipment and construction materials should be included in the different life cycle stages

EN 15804

 In EN 15804, the conventional life cycle stages take into account the related transportation processes that occur during the production, construction, use and end-of-life phases.
6.3.4.2 Product stage
6.3.4.3 Construction stage
7.3.2.1 A4, Transport to the building site
7.3.2.2 A5, Installation in the building
7.3.4 End-of-life

=> Transport of goods, wastes, construction equipment and construction materials should be included in the different life cycle stages
Guidance
 Any life cycle stages (i.e. Modules A1–A3, A4, A5, B and C) should include the related transport processes. The practitioner should be aware that even if a life cycle stage is labelled e.g. A3 ‘Manufacturing’, internal transport of goods can occur. Thus the transport-related impacts theoretically occur for each life cycle stage. For any gate-to-grave information module, additional information to support the generation of LCA data at the building level can be provided by means of a scenario. Module A4 includes only transport from the factory to the construction site. Earlier transport journeys are included in Modules A1 and A2. For example, in an EPD for a steel cladding panel, the transport of iron ore to the steelworks is included, with the extraction of iron ore, and the production of steel sheet via the blast furnace and basic oxygen furnace, in Module A1.  The transport of the steel sheet to the panel manufacturer is included in Module A2, panel manufacture is included in Module A3, and transport from the panel manufacturer to the construction site in Module A4.Transport is generally a significant impact only for materials with very low manufacturing impact, such as aggregates and timber. Also, transport by water has much lower impact than transport by road. Guidance mentioned in the cut-off rules aspect should be adopted for the inclusion of transport processes in the life cycle of a building or a product.Default values for average distances, truck types and load factors should reflect the actual transport. For average LCA data, the use of average values may be sufficiently accurate. Average values can be found in various literature sources e.g. in some transport reports available for each country, or in the documentation of transport LCA datasets from individual databases (e.g. ecoinvent, ELCD, GaBi). Further guidance adapted to the study type and to the life cycle stage is given in the other aspects.

G-16 (Buildings) / G-15 (Products) Accounting for carbon storage/carbon sequestration

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Aspect G-16 (Buildings) / G-15 (Products) Accounting for carbon storage/carbon sequestration
Description
 Some products (e.g. wooden products) take up atmospheric carbon dioxide while producing biomass. Concrete- and lime-based products can also take up atmospheric carbon dioxide through recarbonization during the use phase . By using these materials or products, this fixed CO2 is stored during the service life of the product. It is then released during combustion processes, or in landfill during full or partial decay of the biomass, as either CO2 or methane, which itself may be captured to produce CO2. Owing to the storage of carbon of biogenic origin in some products during the use of these materials, the CO2 stored is not released in today’s ecosphere but at some future date. Usually, 100-year assessment periods for the fate of greenhouse gases are taken into account in LCA studies (use of the indicator global warming potential, GWP100), but, depending on the case, this period can be insufficient to counteract the storage period.In this case, how should the biogenic carbon be taken into account? Should this temporary storage effect be accounted for? Also, the matter of sequestration of carbon in soils and organic matter due to land-use changes is frequently discussed. How should this aspect be treated?

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 As a conservative approach, the storage or sequestration of biogenic carbon as an additional benefit should not be accounted for, as this is a temporary effect. All greenhouse-gas-related environmental impacts should be quantified solely with the use of IPCC’s GWP-100 impact category. This means that the uptake of carbon dioxide into biomass is considered in the inputs to biomass production, and the emissions of biogenic carbon (as carbon dioxide or methane) are considered in the outputs.
Rules from

ILCD

 

 Provisions 7.4.3.7 Future processes and elementary flows
Citation from provisions 7.4.3.7:
“VII) SHALL – Inventory temporary carbon storage and delayed GHG emissions: only if temporary carbon storage in bio-based goods is considered […] delayed emission as CO2 or CH4 shall be modelled analogously to delayed emissions of fossil carbon dioxide and other greenhouse gases” Additional citation from the ILCD Handbook:The uptake of “carbon dioxide” by plants shall be inventoried under “resources from air”. This applies to all photosynthetic organisms.

The ILCD Handbook recommends that for better methodological clarity and flexibility, as well as easier communication, the release of carbon dioxide and methane be additionally differentiated between fossil and biological sources. Both the uptake of carbon dioxide from the atmosphere and the release of both fossil and biogenic carbon dioxide are assigned characterization factors for the impact assessment. The full provision for inventory of temporary carbon storage and delayed GHG emissions can be found in the ILCD Handbook.
Guidance
 This aspect is under intense discussion within various organizations. Different perceptions exist, and various documents propose different solutions to this question. For example, some documents define ‘discounts’ for the temporal storage of carbon in products. Others suggest, for example, reduction factors to be applied to GWP results for a temporal sequestration of carbon in soil and organic matter due to land-use change.In order to be flexible concerning future development of and consensus-building on this aspect, it is helpful to track carbon with a distinction made between biogenic and fossil sources. For example, in the background LCI databases, it is likely that elementary flows will be found such as:Resources: ‘carbon dioxide (resource), in air’Air emissions: ‘carbon dioxide (fossil), in air’ and‘carbon dioxide (biogenic), in air’.This is also valid for methane and carbon monoxide.Further information can be found in the following sources:

  • ISO working group on carbon footprint;
  • PAS 2050.
  • Standard in preparation in CEN TC 175 prEN 16449: ‘Wood and wood-based products – Calculation of sequestration of atmospheric carbon dioxide’ (status: under approval)

The treatment of biomass at the end of life is covered in the aspects of Module C and this should be considered alongside this guidance.