G-24 Choice of LCI/LCIA datasets for simplified LCA

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Aspect G-24 Choice of LCI/LCIA datasets for simplified LCA
Description
 Different LCI/LCIA data are needed to assess the environmental impacts of buildings. They make it possible to quantify the different impacts related to the building products and equipment, the construction site, the operational energy and water uses, and the deconstruction of the building. Depending on the study type (screening, simplified, complete), different LCI/LCIA data can be used in practice, depending on their availability not only at the European level but also in a national context (average, generic or specific LCI/LCIA data for the building materials, products and processes).How can this be addressed for 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 LCA practitioner or the user of dedicated building LCA tools should use adapted data for the description of the building components in simplified LCA.In contrast with screening LCA, the data should reflect more closely the building element, product or material. They can either represent a full building component (e.g. 1 m2 concrete block wall insulated with wood wool), a building product (e.g. 1 m2 of rockwool) or a building material (e.g. 1 m3of ready-mixed concrete), depending on the need of the practitioner and the stage of the building project. Provisions for the choice of data to use for simplified LCA for the construction site, the operational energy and water uses, and the deconstruction activities are described in the corresponding aspects.Generic LCA data for the building elements cited above should come from available European or national generic LCA databases. It is possible to use average data (e.g. average EPD) if generic LCA are missing, or are less appropriate to the context of the study.

Generic LCA data may represent (if possible and if relevant) the total consumption mix in Europe (if the study is used for European projects) or in every European country, or the production mix in Europe or in every European country, or the production mix of a neighbouring country, using appropriate rules to adapt the generic data to the new context.
Rules from:

EN 15978

 9.4 Type of data for the assessment
The type of LCA data for the assessment referred in EN 15978 to the CEN/TR 15941. The choice of the data will depend on several aspects, including the stage of the building project, the intended use or scope etc. According to EN 15978 the data (bill of quantities, building description of components or the LCA data) may be given in different types: aggregated, specific, generic or average. They describe different levels of specificity concerning the description of the building components as well as the representativeness of the LCA data.

ILCD

 7.5 Developing generic LCI data
7.6. Selecting secondary LCI datasets
7.7 Averaging LCI data
According to the ILCD Handbook, a dataset is a generic dataset if “it has been developed using at least partly other information then those measured for the specific process. This other information can be stoichiometric or other calculation models, patents and other plans for processes or products, expert judgements etc. Generic process can aim at representing a specific process or system or an average situation.”

ILCD also states that “a generic data represents a typical variant of the process or the system, an average dataset represents the average situation for the process or the system, in both cases within a specified geographic region and time. The difference lies in how the dataset is modelled: in the first case the product and its life cycle is specified with typical (or representative characteristics and the inventory is modelled accordingly. In the second case several products (or technology or production plants) are separately modelled and the inventories are subsequently averaged.”

According to ILCD, the supply mix for an average data is the production mix plus the import mix, i.e. the mix of what is available in the country for consumption. This applies to generic such as the consumption mix of reinforcing steel in country A.

Figure 13 presenting the trade relations between countries as a basis for calculating the production, consumption and supply mixes of products [ILCD 2011a]
Guidance
 In practice, the LCA data for a simplified LCA should represent the building elements, products or materials more closely than the data used for a screening LCA. Three different practical recommendations can be given for the use of data on the building elements, the associated LCA data and the currently available generic LCA databases.

1) Practical guidance for the use of data describing the building elements

The data describing the building components can correspond to generic typical components using default values for the major included products (width, thickness etc.). It may be possible to parameterize the thickness of the key included products (e.g. insulation or structural products) for each study or use.

Other data include building products and materials LCA data. These ‘raw’ data usually serve when deriving data for building components or parts of the building. Consistency should be ensured between the different levels of data (part of the building, components, products and materials).

2) Practical guidance for the use of generic LCA data for a European or national context

Examples of generic data on building products representing the ‘consumption mix’ can be found e.g. for the reinforcing steel sold on the French market in [Gomès 2012]. However, generally speaking, generic national data representing the ‘consumption mix’ in the various European countries may be missing. In this case, the use of existing generic LCA data (from neighbouring European countries) or industry-based data (from the national context) can be used as proxy data, using appropriate adaptation or contextualization rules. More guidelines on this topic can be found e.g. in [Hodkova 2012].

3) Practical availability of generic databases in Europe that can be used by the practitioner

The building practitioner may use existing European or national databases to collect generic LCA data to describe the building elements, products and materials, depending on the needs. Examples of such databases can be found e.g. on the LCA resources directory of the European Commission – Joint Research Centre, section ‘Databases’. Generic databases (mainly at the global or European level) include, for example, the ELCD, ESUCO and ecoinvent databases.

Other generic databases developed in some European countries include, for example: the German Ökobau.dat, the Swiss Catalogue Construction/KBOB databases, the French DIOGEN generic LCA database for construction materials used in civil engineering applications, and the various generic databases that are included in LCA software for buildings.

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