D-01 Inclusion of reuse, recovery or recycling potentials (Module D) in building or product LCA

Aspect D-01 Inclusion of reuse, recovery or recycling potentials (Module D) in building or product LCA
Module D describes the net benefits related to exported energy and secondary materials, secondary fuels or secondary products resulting from reuse, recycling and energy recovery that take place beyond the system boundary for both products and buildings. Displaying Module D separately is a very recent outcome of expert discussions. Before, in some life cycle studies, Modules C (end of life) and D were presented jointly in one life cycle stage, and different approaches were used in other situations such as the use of recycled material. As this is not necessarily done any more, under what circumstances is it necessary or mandatory to include Module D in the life cycle results?

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 EN 15978 for building level calculation states [8.8] that “If relevant and available, Module D addresses the net environmental benefits or loads resulting from reuse, recycling and energy recovery”, and [12.6] “The communication from the report may be simplified according to the following rules: [...] if relevant information is provided at the product level on Module D, this information should be reported.”The first point states that Module D should be included if it is relevant, and data are available. The second suggests that if any product used in the building provides data for Module D, this must be reported at the building level, although this is not a mandatory requirement of the standard (‘should’, not ‘shall’).

In general, Module D should be reported both on the product and at the building level, but it is clear from both EN 15804 and EN 15978 that Module D is provided “to help with transparency on the benefits and loads of processes beyond the system boundary of the object of assessment”. Deviating from EN 15978 for benchmarking purposes with other studies where recycling credits have been included, Module D may be included in the building life cycle, but other aspects of system boundary and treatment of recycling (such as use of the cut-off approach for inputs) may render such comparisons invalid.

Rules from:

EN 15978

7.4.6 Boundary for the benefits and loads beyond the system boundary (Module D)

EN 15804

6.2.7 D Benefits and loads beyond the system boundary, information module


ILCD uses different approaches for the system boundaries and the benefits of recycling, and Module D is therefore not discussed.
If Module D data are not provided by manufacturers within the EPD, default values can be used, or values estimated by the building assessor. As these values may be worse than the calculated values for the product, this could be an incentive for producers to provide data at a product level.It could be argued that Module D is not relevant to the life cycle assessment of both products and buildings, as it is outside the system boundary, although the TC 350 standards state that Module D can be provided as part of the building assessment information to provide additional transparency on benefits and loads beyond the system boundary.

The benefits of exported energy (for example from excess generation from integrated renewable, or from the capture of landfill gas from disposal in C4) must be reported in Module D, and this must be reported separately from any other flows, but Module D is an optional module for any product EPD, and at the building level EN 15978 states regarding Module D that “Where a material flow exits the system boundary and has an economic value or has reached the end-of-waste stage and substitutes another product, then the impacts may be calculated” [7.4.6], and 8.1 states “If information on Module D is communicated in a building assessment”, which shows that it is not a requirement that it be communicated. It is clear that Module D does not need to be calculated for all materials; only where this is defined at a product level must it also be considered in Module D at the building level. However, depending on the relevance of and attitude to the information provided in Module D, practitioners are free to generate data within Module D for products that have not provided this information within their EPD, subject to the normal rules for scenarios regarding current practice.

The system boundary for the building life cycle may be extended to include Module D if full life cycle results are assessed in a context where credits due to system expansion are typically accounted for. This is, for instance, the case in the German Sustainable Building labelling system (DGNB). The practitioner should be very clear that changing the system boundary of the object of assessment may introduce the possibility of double-counting benefits or loads, and should ensure this does not occur.

The other use of Module D is to assess design for dismantling or recycling building alternatives.

Back to 7 Aspects concerning Module D

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