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B- 25 Assessment of operational water use in screening LCA

Aspect B- 25 Assessment of operational water use in screening LCA
Description
The operational water use assessment includes water used during the operation of the building, together with their associated environmental impacts and aspects, including the production of drinking water and the wastewater treatments. Moreover, a link between domestic hot water and energy use should 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 The assessment of the water consumption during use phase should be included into the LCA studies in order to be consistent within the overall assessment methodology (use of a “net fresh water” indicator for different life cycle phases). Moreover, usually, the water consumption during use phase is the most important, compared to the other phases of the life cycle.It should be assessed using statistical data for screening (see guidance). The upstream and downstream processes linked to the operational water use should be modeled using generic LCA data.
Rules from:

EN 15978:

 

7.4.4.8 Boundary of the operational water use (Module B7)

EN 15978 states that the boundary of the operational water use should include water used during the normal operation of the building together with associated environmental impacts due to its treatment (before and after use). This include drinking water, water for sanitation, domestic hot water, irrigation, water for heating, cooling, ventilation and humidification and other specific water use (e.g. fountains, swimming pools, saunas). Water consumption of not building-related equipment (e.g. dishwashers, washing machines) could be included within the assessment. This issue should be reported separately.

EN 15804:

7.3.3.3 B6, use of energy and B7, use of water

Guidance
In order to calculate the water consumption for screening LCA, a methodology based on the statistical data on water consumption at building scale may be used (e.g. in France the average water consumption is about 50 m3/person/year for 2.3 person/dwelling [INSEE, 2006], i.e. 115 m3/dwelling/year). To volume of consumed water, environmental impacts linked to the production/adduction, respectively wastewater treatment should be associated.For the screening or simplified LCA only the most representative technologies should be considered by using a generic LCA data available in background LCI databases (e.g. ELCD, GaBi or Ecoinvent).

Additional guidance:

Some of the labeling schemes (e.g. DGNB) also use a water indicator which is based on average water consumption of the sanitary system, rainwater and grey water use. Such an indicator may be of help to calculate operational water use for simplified LCI (module B7).

Any comparative assertion should be supported by a sensitivity analysis of different parameters and hypothesis considered during the assessment, especially on the user behaviour. The baseline scenario should be development by using default values for all the parameters. The default values should be defined based on statistics on the most common values of the moment. Therefore regular update is necessary (as the different equipments characteristics evolve relatively fast).

B-26 Assessment of operational water use in simplified LCA

Aspect B-26 Assessment of operational water use in simplified LCA
Description
The operational water use assessment includes water used during the operation of the building, together with the associated environmental impacts and aspects, including the production of drinking water and wastewater treatment. A link between domestic hot water and energy use should also 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 Assessment of the water consumption during the use phase should be included in the LCA studies in order to be consistent within the overall assessment methodology (the use of a ‘net fresh water’ indicator for the various life cycle phases). Water consumption during the use phase is usually the most important, compared with the other phases of the life cycle.Operational water use may be assessed using a top-down approach for simplified LCA (see guidance). The upstream and downstream processes linked to the operational water use may be modelled using generic LCA data.
Rules from:

EN 15978

7.4.4.8 Boundary of the operational water use (Module B7)EN 15978 states that the boundary of operational water use should include water used during the normal operation of the building together with the associated environmental impacts due to its treatment (before and after use). This includes drinking water, water for sanitation, domestic hot water, irrigation, water for heating, cooling, ventilation and humidification, and other specific water uses (e.g. fountains, swimming pools and saunas). Water consumption of non-building-related equipment (e.g. dishwashers, washing machines) could be included within the assessment. This issue should be reported separately.

EN 15804

7.3.3.3 B6, use of energy and B7, use of water
Guidance
In order to calculate the water consumption for simplified LCA, a methodology based on a top-down approach could be followed. It consists in estimating the total consumption by taking into account the economies that can be achieved by using some water saving devices (e.g. dual-flush toilet systems) compared with the average water consumption (e.g. 50 m3/year/person, i.e. 115 m3/dwelling/ year) or the extra consumption due to some specific systems (e.g. fountains, swimming pools, saunas).In addition to the volume of water consumed, the environmental impacts linked to the production, respectively wastewater treatment should also be considered.For screening and simplified LCA only the most representative technologies should be considered by using generic LCA data available in background LCI databases (e.g. ELCD, GaBi or Ecoinvent).

Additional guidance

Some of the labelling schemes (e.g. DGNB) also use a water indicator that is based on the average water consumption of the sanitary system, rainwater and greywater use. Such an indicator may be of help in calculating operational water use for simplified LCI (Module B7).

Any comparative assertion should be supported by a sensitivity analysis of the various parameters and hypotheses considered during the assessment, especially regarding user behaviour. The baseline scenario should be developed by using default values for all the parameters, defined according to statistics on the most common current values. Regular updating is therefore necessary (as the various equipment characteristics evolve relatively quickly).

B-27 Assessment of operational water use in complete LCA

Aspect B-27 Assessment of operational water use in complete LCA
Description
The operational water use assessment includes water used during the operation of the building, together with the associated environmental impacts and aspects, including the production of drinking water and wastewater treatment. A link between domestic hot water and energy use should also 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 Operational water use should be assessed using a bottom-up approach (see guidance). The upstream and downstream processes linked to the operational water use should be modeled using specific LCA data (e.g. EPD based on industry), or else may be modeled with generic LCA data (e.g. if no specific data are available, or if the impact categories do not match the goal and scope of the study). Assessment of the water consumption during the use phase should be included in the LCA studies in order to be consistent within the overall assessment methodology (the use of a ‘net fresh water’ indicator for the various life cycle phases). Water consumption during the use phase is usually the most important, compared with the other phases of the life cycle.
Rules from:

EN 15978

7.4.4.8 Boundary of the operational water use (Module B7)EN 15978 states that the boundary of operational water use should include water used during the normal operation of the building together with the associated environmental impacts due to its treatment (before and after use). This includes drinking water, water for sanitation, domestic hot water, irrigation, water for heating, cooling, ventilation and humidification, and other specific water uses (e.g. fountains, swimming pools and saunas). Water consumption of non-building-related equipment (e.g. dishwashers, washing machines) could be included within the assessment. This issue should be reported separately.

EN 15804

7.3.3.3 B6, use of energy and B7, use of water
Guidance
In order to calculate the water consumption for complete LCA, a methodology based on a bottom-up approach should be used. It consists in estimating the total consumption by taking into account the characteristics of each water consumption device (e.g. 6 L flushing system), the use factor (use frequency) and all the other influencing parameters (e.g. dwelling surfaces, external use, etc.). The bottom-up approach is the most suitable, since it allows a finer sensibility analysis, and hence more efficient performance improvements/optimization.In addition to the volume of water consumed, the environmental impacts linked to the production, respectively wastewater treatment should also be considered.For a complete LCA, all types of water used to produce domestic water (whether for drinking or not) should be considered, i.e. public grid water (drinking water), rainwater, underground water, surface water and greywater. The particular national regulations on the use of different types of water should be specified (i.e. rainwater or greywater). For example, in France rainwater use was regulated in 2008.The French regulation allows the use of rainwater for only two uses indoors (WCs and floor washing), and experimentally for washing machines.For each type of technology, specific LCA data (e.g. EPD on waste water treatment provided by the industry) may be used in a complete LCA. If the practitioner intends to assess impact categories outside the scope of a PCR (e.g. EN 15804), the corresponding EPD on waste water treatment may not be suitable. In this special case only, generic LCA data may be used (assuming that the full inventory is available, and makes it possible to calculate the various impact categories available, e.g. in the ILCD Handbook).

Any comparative assertion should be supported by a sensitivity analysis of the various parameters and hypotheses considered during the assessment, especially regarding user behaviour. The baseline scenario should be developed by using default values for all the parameters, defined according to statistics on the most common current values. Regular updating is therefore necessary (as the various equipment characteristics evolve relatively quickly).

B-28 (Buildings) / B-10 (Products) Accounting of different types of waste water treatment

Aspect B-28 (Buildings) / B-10 (Products) Accounting of different types of waste water treatment
Description
The environmental impacts are different for the various methods of waste water treatment. The system boundaries for waste water treatment considered within the studies (e.g. public sewage system, on-site treated water) and the classification of waste water treatment need to be consistent.

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 This aspect should be modelled only when it is a special focus of the study, or for a complete LCA, unless it is believed to be a dominant contributor to the environmental impacts of the assessed system. In this case, the real situation should be modelled, and alternative scenarios can be developed as sensitivity analyses. These scenarios should be documented as transparently as possible.
Rules from:

EN 15978

8.6.6 Scenarios for operational water use (Module B7)According to EN 15978, For building studies, water use (treatment and supply) and waste water treatment should be considered in Module B7.  Energy to heat or cool water used would be included in Module B6.

EN 15804

6.3.4.4.3 B6 – B7 use stage information modules related to the operation of the building:According to EN 15804, Module B7 deals with operational water use within the building.  As such, in product LCA it would be included only where building integrated technical system products have an operational water demand. Additionally, the impacts of waste water treatment should be considered for the water used.Product-related water use and waste water treatment during the extraction or manufacturing process should be included in Modules A1–A3, during construction in Module A5 and from maintenance (e.g. cleaning) in Module B2.
Guidance
In general, waste water treatment as part of material production is included in background datasets. The use of generic waste water treatment data from background databases may ease the assessment of this aspect, and should typically be sufficient for construction-related LCA studies (except for studies that include processes with significant pollution of waste water, such as varnishing processes with high waste water runoff).Regarding the way to treat wastewater in an improved model e.g. for a complete LCA, all types of wastewater treatment should be considered: 1) on-site treatment (different technologies); 2) public sewage system (combined sewer system, both rain and grey/blackwater or separate sewer system); 3) combined technologies (e.g. one technology for on-site treatment and one technology for the  public sewage system). Specific LCA data representative of each technology should be used (if available).

B-29 Building services

Aspect B-29 Building services
Description
Should building services (e.g. energy service companies, landlords, etc.) and energy performance contracting be considered in LCA and, if so, how?

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 Relevant for LCA studies are the upstream energy supply mechanisms, which need to be adequately reflected, and the energy demand of a building. Any business models of how the energy is provided are only of relevance if the technical energy supply is affected.
Rules from:

EN 15978

7.4.4 Boundaries of the use stage (Modules B1–B7)

7.4.4.1 General

EN 15804

6.2.4 B1–B5, Use stage, information modules related to the building fabric

6.2.5 B6-B7, Use stage, information modules related to the operation of the building

Guidance
Different economic models, e.g. of energy supply and its technical consequences, could be assessed by means of scenario analysis. For an LCA study, it is not the economic model behind an operation that is not the decisive point, but the technical consequences of different economic models.

B-31 (Buildings) / B-11 (Products) Distinction between Modules B2, B3, B4 and B5

Aspect B-31 (Buildings) / B-11 (Products) Distinction between Modules B2, B3, B4 and B5
Description
Modules B2 to B5 cover the impacts related to the service life of building and building parts, whether it is a light modification, such as a small maintenance operation or an important retrofit (rehabilitation).It is sometimes difficult to determine which module a specific operation should be attributed to. The present aspect proposes a common definition of these modules, plus recommendations on how to use them at the product and building scale.

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 Standards EN 15804 and EN 15978 provide definitions and examples of aspects B2 to B5. The LCA practitioner should refer to these standards.B2 – Maintenance encompasses all actions related to maintaining a product or building part – i.e. replacement or reparation of a used, damaged or worn part of the product (a part, but not the entire functional unit) in a state in which it can perform its functions [EN 15978]. According to EN 15978, this applies to planned actions, and should include:

  • preventive and regular maintenance operations;
  • cleaning operations.

Maintenance actions are part of the ‘intended use’ definition that should be provided with a product’s reference service life (see EN 15804, annex A and 7.3.3.2 Reference service life). The reference service life (RSL) is valid under a specific set of conditions, notably the in-use environment (e.g. UV, heat, humidity, etc.), and proper implementation and maintenance that comply with the producer’s recommendations and with state-of-the-art practices. The RSL should be used to calculate the number of replacements. See the aspects: ‘Definition of the service life of a building product’ and ‘replacement frequency’ for additional information.

B3 – Repair encompasses all actions related to returning a product or building part to an acceptable condition in which it can perform its required functional and technical performances [EN 15804], including:

  • corrective, responsive or reactive treatment of a construction product;
  • replacement of a broken component or part because of damage (replacement of a whole element should be assigned to replacement).

The example given in EN 15978 and EN 15804 is a window with a broken pane.

–> Although the distinction between the maintenance and repair modules is not straightforward, the example given for repair falls outside the scope of the intended use that defines reference service life.

B4 – Replacement covers the replacement of a whole construction element [EN 15804], including the production and installation of a new (and identical) construction element. Examples given in EN 15978 include replacement of a partition wall, and replacement of a boiler or heating system.

–> The replacement module is distinguished from the maintenance and repair modules by the fact that a complete component or part is replaced (maintenance include the replacement of subcomponents, and repair the replacement of damaged parts). Although this ultimately depends on the breakdown of the building into subcomponents, it seems reasonable to understand it as the replacement of a complete functional unit such as defined in the EPD.

B5 – Refurbishment covers concerted programmes of maintenance, repair and/or replacement activity across a significant part or whole section of the building [EN 15804]. Examples provided include: ‘a major change of the internal layout (partitioning)’, a ‘change of the technical system related to heating’ and ‘modification for the purpose of a […] change of use’ [EN 15978].

–> The refurbishment module addresses important modifications that would impact on several building components, and modify building performances and/or functions.

All these aspects are related to the notions of durability and service life planning, as described in the ISO 15686 series. Relations between the type of operations and performance of a given product or building part could be represented as follows:

Figure 18: Example of performance over time relation depending on operations [EN 15804]

This figure is shown only for explanation purpose, and many other cases are possible, such as:

  • performance stability over the reference study period;
  • overall decrease of performance despite maintenance operations;
  • failure at implementation.

Furthermore, “service life planning can only address foreseeable changes. Since service life planning is concerned with foreseeable risks, it is not applicable to the estimation of obsolescence […] or to defective performance resulting from unforeseeable events or processes” [ISO 15686-1, part B.8.2.].

In the case of sound statistical feedback on the replacement rate of a specific product for a given country or region, it is unlikely that a clear distinction between the causes of replacement could be easily made. In that specific case, replacement causes would naturally encompass all cases: i.e. premature failure, failure due to foreseeable ageing (i.e. RSL) and obsolescence. The figure below presents a hypothetical distribution of replacement rate according to the main causes of replacement (including building deconstruction).

Figure 19: Replacement rate [EN15804]

 

Rules from:

EN 15978

7.4.4.1 General
8.6.3 Scenarios for maintenance, repair, replacement

EN 15804

6.3.3. Reference service life
6.3.4.4.2  – B4 Replacement
Annex A
Guidance
As the distinction between Modules B2 to B5 is not straightforward, it is recommended that the following principles be applied when developing product and building LCA. These principles are based solely on the distinction between the causes of end of life:–> For end of life related to performance decrease over time (e.g. aging, decay, degradations, etc.):

  • causes related to foreseeable events (i.e. related to reference service life) in a defined set of conditions lead to maintenance and replacement scenarios;
  • causes related to unforeseeable events lead to repair scenarios.

–> For end of life related to modification of expectations regarding the building’s performance level or functionalities (e.g. obsolescence, such as modification of activities inside the building, modification of regulation, etc.):

  • causes lead to refurbishment scenarios.

B2 – Maintenance:

For product LCA, this module should cover all operations necessary to maintain the performance of products, or to return them to their original level, including scheduled replacement of parts and subcomponents. Example include: scheduled replacement of boiler parts; scheduled replacement of light bulbs from luminaires; repainting of a wall, door or window frame; replacement of small elements of roofing, such as tiles (e.g. a certain number of tile per 10 years per square metre), etc.

For building LCA, maintenance should take into account maintenance modules as provided within EPD, as well as additional information if needed (e.g. current or state-of-the-art practices, recommendations, etc.).

–> Maintenance should be understood as the set of operations performed under normal conditions. This applies in a given context (e.g. maintenance of a product could change, depending on the climate). Product modification and operations caused by accidents, improper installation or handling, unforeseeable events (such as flood), etc. should be covered by the repair module (see below).

–> Maintenance scenarios at the building scale should be consistent with the building’s physical structure: maintenance of a given component should take into account the influence of neighbouring components (e.g. accessibility).

B3 – Repair:

For product LCA, the repair module should not be included in the baseline scenario.

For building LCA, the repair module should not be included in the baseline scenario. The repair module may cover all operations related to product modification outside the scope of the maintenance module – that is, outside the scope of normal conditions, including improper use of a product, unforeseeable events such as flood or vandalism, etc.

–> For existing buildings, repair scenarios could be based on the history of the building (i.e. examples based on previous reparation);

–> For new buildings, repair scenarios could be used to assess the environmental impacts of a specific risk (e.g. the impact of reparation due to flood, the impact of improper installation that causes damage, etc.).

B4 – Replacement:

Replacement is necessarily related to the reference service life. Replacement occurs at the end of life of a product: that is, when it does not meet its initial performance requirements (modification of the requirements after product installation should be considered as obsolescence, and be covered by a specific scenario: see below). The number of replacements is further described in the aspect ‘Replacement frequency’.

–> It is recommended that replacement caused by events that are outside the scope of condition defined by the reference service life be treated as repair.

For product LCA, replacement covers the replacement of the whole functional unit by a new one after RSL. The boundaries of replacement include [EN 15978]:

  • production of the replaced component and ancillary products;
  • transportation of the replaced component and ancillary products, including production impacts and aspects of any losses of materials during transportation;
  • the process of replacing the components and ancillary products;
  • waste management of the removed component and of ancillary products;
  • the end-of-life stage of the removed component and of ancillary products.

Most of these may be similar to other modules for cradle-to-grave product LCA, for instance:

  • The transport scenario of the new component may be similar to A4 – Transport.
  • The replacement process may be similar to C1 – Deconstruction.

–> If no differences arises from a comparison between a replacement scenario and an installation scenario (including related production, transport, end of life, etc.) then a replacement scenario is not necessary. In any case, it should be clearly stated whether or not the assumptions regarding B4 modules are similar to those used for other modules (e.g. the replacement process is different from the initial implementation because of the building structure, etc.).

For building LCA, replacement should include:

  • replacement modules as described in cradle-to-grave EPDs (or cradle-to-gate EPD with corresponding option);
  • additional LCA data to cover components without EPD.

–> Replacement scenarios at the building scale should be consistent with the building physical structure. Replacement of a given component should take into account the influence of neighbouring components (e.g. accessibility, possible replacement of other components, etc.).

B5 – Refurbishment

For product LCA, no refurbishment module need be included in the baseline scenario, as this is highly dependent on information at the product scale.

For building LCA, the refurbishment module should not be included in the baseline scenario if the building service life is equivalent to the reference study period. Additional refurbishment scenarios may be developed. For example:

  • to assess the modification of building functions (e.g. switching from a commercial building to habitation);
  • to assess the effect of an expected regulation that would affect the buildings.

–> A refurbishment(or deconstruction/new construction) scenario should be developed if the service life of the building is less than the reference study period.

It is recommended that a refurbishment scenario be developed when long reference study periods (>100 years) are being considered, as modification of the building use is expected over such a period of time. Refurbishment scenarios could also be developed if the reference study period is longer than the reference service life of the load-bearing components and structural elements.

Additional recommendations:

The progressive loss of performance of some components will have an impact on the overall performance of the building (e.g. loss of performance of insulation may lead to an increase of energy demand for heating). If sufficient data are available, these aspects should be addressed using a sensitivity analysis.

According to NEN 15804 (Annex A), Reference service life “could be based on empirical, probabilistic or statistical data and shall always taking into account the intended use (description of use) as described in ISO 15686-1, -2, -7 and -8” [EN 15804, Annex A].

8.1. Overview

This chapter addresses aspects that are related to life cycle stage C. All the aspects of this chapter provide provisions, rules and guidance for the goal and scope definition and the inventory analysis steps according to [ISO 14040] and [ISO 14044]. The following list describes the aspects addressed in Module C.

8.  Aspects concerning Module C

Back to EeBGuide Guidance Document Part B: BUILDINGS

C-01 Demolition/deconstruction – screening and simplified LCA

Aspect C-01 Demolition/deconstruction – screening and simplified LCA
Description
The deconstruction and demolition stage involves quantification of the impact related to the end of life of the constructed system. For example, if it is a reinforced concrete building, deconstruction activity will consist mainly in separating the reinforcing steel from the concrete. During this operation, energy is consumed, and pollutants are emitted to the air. In this context, should the demolition and deconstruction stage be considered in the context of a screening or simplified 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 demolition and deconstruction aspects may be included for screening and simplified LCA. Generic data should be taken from LCA databases if available.
Rules from:
EN 15978:

8.7.2 Scenarios for deconstruction – Module C1

EN 15804:

6.2.6 C1-C4 End-of-life stage information modules

Guidance
Depending on the goal and scope of the study, this aspect may be neglected, owing to its minor relevance.The practitioner may use ratios based on the materials impact (e.g. 3% for GWP in the case of concrete) if the purpose of the assessment is to obtain a rough estimate of the end of life for specific impact categories.Very few LCA data are currently available in every national context. One option is to use existing generic LCA data on the impact of demolition and the deconstruction process (e.g. the impact of sorting the reinforcing steel from the concrete at the end of life of the building). Such generic LCA data can be found e.g. in the Ecoinvent database.

The practitioner should be aware that the data on demolition process may not be fully adapted to the context. Another option is to define generic data with stakeholders (collection of specific data).