G-10 Definition of system boundaries for products

Aspect G-10 Definition of system boundaries for products
The system boundaries of product LCA can be different, depending on the goal and scope of the study. If the goal is to create an EPD, then the practitioner is likely to follow the EN 15804 standards. But even for EPD, the system boundaries can vary, depending on the type of data: cradle to gate, cradle to gate with options, or cradle-to-grave. For LCA used in ecodesign, it may be relevant to include the recycling potentials of the products, thus extending the system boundary (a cradle-to-cradle approach) – that is, including Module D if the study complies with EN 15804. Generally speaking, the main issue for any product LCA is to define what to include, especially for the production stage.How can the system boundaries be defined for product 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 practitioner should refer to the ILCD Handbook, or otherwise EN 15804, depending on the goal and scope of his study.For LCA studies that are compliant with EN 15804, the practitioner should be aware that different system boundaries can be selected: cradle to gate, cradle to gate with options, or cradle to grave.

If the results are intended to be used for comparative assertions, then the rules used to define the system boundaries should follow the ILCD Handbook.

Rules from:

EN 15804

6.3.4 System boundaries


Provisions: 6.6 Deriving system boundaries and cut-off criteria (completeness)“I) SHALL – Scope of LCA

II) SHALL – Processes within the system boundary

III) SHALL – Flows across the system boundary

IV) SHALL –System boundary diagram

V) SHALL – List of exclusions

VI) SHALL – part-system and system-system relationships

VII) SHALL – System-external off-setting

VIII) SHALL – Quantitative cut-off criteria”


Provisions: 7.2.3 Identifying processes in attributional modelling

“[…] I) SHALL – Identifying processes within the system boundary

         I.a) Start from central process

         I.b) Foreground system

         I.c) Background system

         I.d) Justify and document exclusion

II) SHALL – Initial processes description”

As an illustration for product LCA, the ILCD Handbook details the different life cycle stages to take into account and the different types of data. It has to be mentioned that the foreground data collection (based on e.g. measured data from company) takes place during the gate-to-gate stage (see below). For the other data (e.g. extraction processes), the data are likely to be based on background data.

Figure 11: Cradle-to-grave, cradle-to-gate and gate-to-gate datasets as parts of the complete life cycle

Different cases can be found in practice. For EPD data, rules from EN 15804 should be applied. These types of EPD system boundary can be found, depending on the goal and scope (e.g. for 1 kg of declared unit for cement, the system boundaries will be only up to the gate of the plant).For E2B EI research projects, product LCA studies may be conducted for the full life cycle. The practitioner is likely to collect foreground data for the gate-to-gate stage among the project partners (e.g. a company involved in the project that would like to assess its new product), whereas for upstream or downstream processes the use of generic data may be sufficient. This last recommendation is also in line with EN 15804.

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