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Tag: Related study objective: comparative assertion

B-20 Operational energy demand for existing buildings – Boundaries and scenarios

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Aspect B-20 Operational energy demand for existing buildings – Boundaries and scenarios
Description
 Several parameters can influence the results of the energy demand at the operational stage of buildings. Among others, the selection of uses (i.e. building-related or non-building-related uses) has a major significance on the energy demand. European standards (EN 15804/EN 15978) recommend that priority be given to taking building-related uses into account; however, it is obvious that non-building-related appliances significantly influence the energy needs of building-related uses (e.g. the thermal gain of appliances decreases the level of heating demand). Moreover, the global gain obtained by technology mixing building energy uses and non-building-related uses (e.g. appliances such as dishwashers and washing machines using domestic hot water produced by solar thermal panels) can be taken into account only if all operational energy uses are also considered into the assessment. The following section aims at providing guidance for screening, simplified and complete LCA 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 existing buildings, measured historical data consumption should be used, if available and applicable. Building-related uses and non-building-related uses may be taken into account according to the goal and the scope of the study.
Rules from:
 EN 15978:
7.4.4.7 Boundaries for operational energy use
8.6.5 Scenarios for operational energy use – Module B6
Guidance
 For existing buildings, if measured historical data consumption are available and applicable (i.e. the objective and the scope of the study are consistent with available data, and future changes in the existing building will not impact on the energy uses), they should be used to calculate the energy demand.Note: the level of detail of energy measurement should allow its use for LCA assessment (i.e. the breakdown of the operational energy demand should be available for each energy carrier). When measured data are available for each energy carrier, building-related and non-building-related uses should be accounted for, as energy monitoring usually does not permit uses to be differentiated. This applies to screening, simplified and complete LCA. For the calculation of energy demand of building-related uses, methods and tools developed by EPA-NR projects may be used.

B-21 Operational energy demand for new buildings – Consideration of user behaviour

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Aspect B-21 Operational energy demand for new buildings – Consideration of user behaviour
Description
 Several parameters influence the results of the energy calculation demand at the operational stage of buildings. Among others, user behaviour may have a major significance on the energy needs. The following section aims at providing guidance for screening, simplified and complete LCA of 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 stand-alone LCA, scenarios may reflect statistical, conventional or specific user behaviour.For comparative assertions, behaviour scenarios for the calculation of energy use should be identical for each alternative. Any deviation between scenarios should be reported and justified.
Rules from:
 EN 15978:
8.6.5 Scenarios for operational energy use – Module B6
Guidance
 For stand-alone LCA, sensitivity analysis should be carried out in order to estimate the significance of the use of a specific scenario instead of a conventional one.

B-22 Operational energy demand for existing buildings – Consideration of user behaviour

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Aspect B-22 Operational energy demand for existing buildings – Consideration of user behaviour
Description
 Several parameters influence the results of the energy calculation demand at the operational stage of buildings. Among others, user behaviour may have a major significance on the energy needs. The following section aims at providing guidance for screening, simplified and complete LCA of existing buildings, and the possibility of taking user behaviour into account regarding the goal and the scope of the study.

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 existing buildings, if measured consumption data are available and applicable for the LCA analysis, user behaviour should be taken into account. Otherwise, the same guidance as for new buildings should be applied.
Rules from:
 EN 15978:8.6.5 Scenarios for operational energy use – Module B6
Guidance
 For stand-alone LCA of existing buildings, if measured historical consumption data are available and applicable (i.e. the objective and the scope of the study are consistent with available data, and future changes in the existing building will not impact on the energy uses), they should be used to calculate the energy demand.Otherwise, scenarios should reflect statistical or conventional user behaviour. Scenarios reflecting specific user behaviour may be used, but sensitivity analysis should be performed in order to provide evidence of the significance of this deviation. For comparative study of refurbishment alternatives for existing buildings, four different types of operation should be considered:

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

A rehabilitation operation consists of a deconstruction operation (removal of products) 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.

If historical data and/or energy monitoring and reflecting user behaviour (e.g. number of users, occupancy scenario etc.) are available, and if they are applicable (i.e. alternatives for refurbishment do not consider a change of use or other major modification of building systems or occupancy) , then scenarios derived from such data should be used to calculate the energy demand for each alternative.

Otherwise, scenarios should reflect statistical or conventional user behaviour. The same scenario should be used for each alternative.

B-23 Operational energy calculation – Allocation of energy production for on-site systems connected to grid”

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Aspect B-23 Operational energy calculation – Allocation of energy production for on-site systems connected to grid”
Description
 Current new buildings may not only be energy-efficient, but can also produce energy on site in multiple ways.The energy produced on site may not only be consumed inside the building, but can also be exported. When energy is produced on site by grid-connected systems (photovoltaic, wind turbines, boiler connected to heating grid etc.), how is this calculated? How are the impacts allocated for both product aspects (e.g. PV cells) and operational energy production?

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 principles for the calculation of exported, imported and on-site energy production should be consistent with the provisions of EN 15978 (see especially reference cases, annex B).

  • Additional provisions for grid-connected systems: the boundaries (i.e. energy uses included) for the calculation of energy demand and exported energy should be homogeneous.
  • The calculation of exported energy and energy consumed on site should consider simultaneity between the consumption and the production.

The method for allocating environmental impact for product aspects and operational aspects should be consistent with the guidance in EN 15978.
Rules from:
 EN 15978:
7.4.4.7 Boundary of the operational energy use (Module B6)
8.6.5 Scenarios for operational energy use (Module B6)Annex B (informative) Exported energy – Case studiesILCD:

6.8.4 Time-related representativeness

Guidance
 The methods for energy calculation should be consistent with the reference cases proposed in annex B of EN 15978.Supplementary recommendations are proposed for on-site energy-producing systems that are connected to the grid (case 3 of EN 15978), as follows.Boundaries for the calculation
The boundaries chosen for calculation of the energy demand should be consistent with those for calculation of the exported energy: if only building-related uses are included, the amount of energy that does not supply the uses considered should be considered as exported energy. Then two situations may be considered:

  1. Including only building-related uses in the scope of the assessment: other non-building-related uses are not accounted. The exported energy will be calculated without considering the energy demand for non-building-related uses, because these are considered to be beyond the system boundary.
  2. Including both building-related uses and non-building-related uses in the scope of the assessment: the two uses are taken into account for the calculation of exported, imported and on-site consumed energy.

Timescale for the energy calculation

For simplified and complete LCA, an hourly scale should be used in order to take into account simultaneity between energy demand and the on-site energy production.

The annual exported energy, imported energy and on-site energy consumption for the considered energy carrier i may be calculated as follows:

 where:

  • Energy production i,h is the amount of energy produced by building on-site systems at hour h for energy carrier i.
  • Energy demand i,h is the amount of  energy needed for the considered building energy use at hour h for energy carrier i.

Allocation of environmental data

Rules should be consistent with EN 15978 for both product and operational aspects.

For imported energy (Module B6) and exported energy (Module D) more representative environmental data should be used. For example. for electricity, hourly environmental data should be used in preference to monthly or annual average data. See the corresponding aspect ‘Dynamic LCA data for assessing the impact of electricity consumption’.

 

B-24 Dynamic LCA data for assessing the impact of electricity consumption

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Aspect B-24 Dynamic LCA data for assessing the impact of electricity consumption
Description
 Energy sources for electricity production may vary significantly according to the season (winter or summer months), the day (weekdays, weekends) and the time within a day. Environmental impacts are strongly influenced by the decision to use annual energy data (i.e. average LCA data) or energy data based on a shorter period (monthly, daily or hourly).

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 Annual average datasets for electricity production should be used in the baseline scenario. Deviating data can be analysed in additional scenarios with transparent documentation and a sensitivity analysis.
Rules from:
 EN 15978:
Not mentioned
Guidance

Dynamic LCA data can be produced by using the hourly data provided by electricity suppliers in each national context. For example, in France, RTE provides hourly data, broken down by source: fossil, hydropower or nuclear energy Based on these proportions, and LCI/LCIA data corresponding to each energy source, dynamic LCA data can be calculated. (Note: the LCI/LCIA data statically aggregate elementary flows.)

Such dynamic LCA data can also be linked to models to predict the environmental impacts in a dynamic way (although very few LCA tools for buildings currently provide such assessment). More detailed information on this aspect can be found e.g. in a French PhD thesis by G. Herfray [Herfray 2011] or in [LoRe-LCA 2011]

B- 25 Assessment of operational water use in screening LCA

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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

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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

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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-09 Modelling of water use

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Aspect B-09 Modelling of water use
Description
 Is B7 relevant at a product level? How should the operational water use be modelled?

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 general, the user has to decide whether  this aspect is important for the product; the consideration of operational water use in Module B7 is necessary only for complete LCA studies.
Rules from:

EN 15804

 6.3.4.4.3 B6–B7 use stage information modules related to the operation of the building
Guidance
 The regulated water use of building-integrated technical systems is determined by the design and use of the building.Attention should be paid to avoid double counting between the product and the building scale.

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

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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).