2.4.2 Simplified LCA

Purposes

A simplified LCA study can be conducted for a quick assessment of a building or a product. The challenge is to adapt the LCA methodology and simplify its use, but to a more advanced LCA stage than for a screening LCA. With a simplified LCA, a pragmatic approach is applied to a building or product LCA. It makes possible studies based on information that is already available, e.g. in the planning process. The simplified LCA lies somewhere between the screening LCA and the complete LCA. It may be adapted by the practitioner or the building stakeholder (e.g. the construction company or the design engineer), and to a given stage of the building planning process. For example, if a construction company conducts a simplified LCA, more precise data can be used for the on-site related impacts, but the study can still rely on the definitions of the screening LCA for the other life cycle stages.

The simplified LCA has to be interpreted as an ‘adapted’ LCA, depending on the effort that the LCA practitioner wants to put in for every life cycle stage and contributor.

Completeness of assessment

The main focus here is on the major contributing input materials, water and energy use. More details should be given, compared with a screening study, in order to increase the representativeness of the study’s results. It is also important to use adapted calculation rules for simplified LCAs (e.g. the possible use of dynamic thermal simulation for assessing operational energy use). More information on the calculation rules can be found in Table 5. The study may consider a more comprehensive set of environmental impact categories than for a screening LCA, for example taken from both EN 15804 and EN 15978, and additional indicators described in the ILCD Handbook (if relevant for the purpose of the study).

Cut-off rules as specified in EN 15978 and 15804 may not apply to simplified LCA studies for buildings, products or services. In early design, for example, not all the input raw materials and components are known in detail, so that some of them have to be omitted. Rather than systematically neglect them, one option is to try to model them using default values . However, life cycle modules, inputs and services should be omitted only if a scientific justification shows their insignificance for the corresponding environmental indicator.

Data representativeness

Compared with a screening LCA, the data used for simplified studies should be more representative of the product, component, element or part of a building under assessment.

Geography

The data used in a simplified study should, as far as practicable, given the existing time and budget constraints, relate to the country where the building or building products are produced or being used. However, as this is not always possible, it is also acceptable to use assumptions, for example using data that represent a country with a similar electric energy grid mix and manufacturing technology. When the goal of the study is to conduct an LCA study within a European project, it is also possible to use average European data, as they are more relevant. The use of global average data should be avoided wherever possible. These provisions do not apply to data on energy, water and waste treatment processes, as national data are preferable (e.g. electric mix, natural gas); or European data can be used if relevant.

Technology

The data should represent the technology used as closely as possible. If no directly applicable dataset is available, a justification for the selection of a dataset should be given.

In the trade-off between the geographical and technological representativeness of data, careful consideration should be given to using the most appropriate data. No general preference can be given here, as this is directly dependent on the geographical and technical parameters.

Precision

Specific, quantitative environmental information on f building elements, products, materials, components or services should be used wherever possible. EPDs of average products may be used, as well as generic LCA data (e.g. if additional impact categories need to be assessed). For other sources of impacts related to the operational energy, water and the construction site, refer to the provisions given in the guidance document.

Consistency

A qualitative assessment of whether the LCA methodology is applied uniformly to the various components and processes should be made in relation to the goal and scope of the study.

Documentation

Use the reporting template provided. The minimum requirements for items reported on can be summarized as follows:

  • Definition of goal and scope
  • Life cycle stages included, and a clear definition of the system boundary
  • Input materials/items included and excluded, with justification, as well as processes for energy, water etc.
  • Overview of calculation rules, and comments on the degree of approximation/uncertainties
  • Impact categories considered (with justification)
  • Limitations
  • Life cycle impact results and interpretation
  • Statement regarding consistency
  • Results
  • Review statement

Communication of LCA report and results

Communication can be internal or external. For external communication purposes, an independent review is needed before publication.

Special precautions have to be taken, if it is intended to conduct comparative assertions on the basis of a simplified LCA. The comparability of the focus areas of a simplified study has to be ensured, and the parameters used and assumptions made for the comparison have to be documented in sufficient detail. The limitations of representativeness have to be estimated, reported and discussed, with regard to the consequences for the comparison.

When performing comparative LCA studies, the same functional equivalent should be used, and similar system boundaries have to be applied to each product system.

Examples of a simplified LCA:

  • Building LCA study for labelling schemes.
  • LCA of a building conducted by a stakeholder (e.g. environmental engineer, construction engineer, etc.) interested in getting a more detailed advanced assessment than from a screening LCA.
  • LCA for developing an environmental fact sheet for a specific product.

2     Methodological approach of the EeBGuide.


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