G-39 (Buildings) / G-37 (Products) Scenario analysis

Aspect G-39 (Buildings) / G-37 (Products) Scenario analysis
Scenario analyses usually refer to future conditions that cannot be fully known by the time the LCA study is conducted. However, the uses of scenarios can meet different goals. Scenarios can look backwards or forwards, and can be linked to different applications. For example, a product is likely to be handed differently in each building. In this context, the use of scenarios may be very helpful in provide complementary results.Within this guidance document, is a scenario analysis necessary? How and when can it be conducted, depending on the study type?

related study objective

stand-alone LCA comparative assertion

related study phase

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

relevant for

new buildings existing buildings building products screening LCA simplified LCA complete LCA
Provisions Scenario analyses may be conducted if relevant for the goal and scope of the study. They should be conducted for individual assumptions and choices in order to explain the impacts of such choices. For these cases, a scenario analysis should be conducted against the baseline scenario (see Chapter 2).
Rules from:
EN 15804
7.3 Scenarios and technical information
Provisions: 9.3.3 Sensitivity check (of accuracy and precision)
A scenario is addressed for each life cycle stage in EN 15804 and EN 15978. However, in addition to the chosen scenario for each life cycle stage it may be useful to assess alternative scenarios.A scenario analysis is closely related to a sensitivity analysis for key parameters. For example, in a scenario analysis, the practitioner may need to look at different building alternatives or reference study periods. The different aspects to consider for the scenario analysis depend on the goal and scope of the study. For example, the scenario analysis can be predictive (forecast, what-if), explorative (external or strategic) or normative (preserving or transforming) [LoRe-LCA 2011].

1) Guidance for building LCA studies

Different aspects can be considered for a scenario analysis, such as the reference study period of a building, the service life of building products, renovation scenarios, energy demand during the use phase, and user behaviour. For more information about scenario analyses for building LCA, please consult the LoRe-LCA report ‘Report on scenario for LCA in constructions’, available online.

2) Guidance for product LCA studies

For product LCA, scenario analysis can be done e.g. for an EPD that is likely to have different impacts in the implementation and use phases. Examples of such products include floor coverings. Having different scenarios enables the building practitioner to select the more appropriate scenarios for the building LCA case study.

3) Specific guidance in EeBGuide reporting templates

Scenario analyses are part of the reporting template for products and buildings case studies. In addition to the baseline scenario, the LCA practitioner is invited to conduct scenario analysis on a relevant set of parameters.

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