C-03 (Buildings) / C-08 (Products) LCA modelling of landfill/disposal

Aspect C-03 (Buildings) / C-08 (Products) LCA modelling of landfill/disposal
Description
Should general rules be defined regarding what is deposited and which LCA data to use? What is the timescale for modelling the fate of disposed material?

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 This aspect depends on the background database used. LCA practitioners need to adopt the procedures from the background database, and have no specific influence on it.The fate of materials should be based on current practice (as a baseline scenario), and not predicted practice in the future (except for sensitivity analysis purposes).
Rules from:

EN 15978

8.7.5 Scenarios for disposal – Module C4

EN 15804

6.3.4.6 End-of-life stage
6.3.7 Data quality requirements

6.3.8 Developing product scenarios

7.3 Scenarios and additional technical information
7.3.4 End-of-life
ILCD Provisions 7.4.4.2 Modelling waste treatment
I) SHALL – Waste and end-of-life product deposition
I.a) Model waste management completely
         I.b) Modelling discarding of goods into nature
I.c) Modelling waste as output
“Note: the use of generic waste treatment models/processes may be considered to limit time and resources required for data collection.”
Guidance
Within building or product LCA studies, the depositing of material in landfill or other disposal mechanisms is typically not a focus of the study, and is modelled with the use of generic data from background databases. These databases have their own modelling principles concerning the fate of landfilled material. The practitioner cannot influence this aspect, but should understand the way in which landfill processes have been modeled. In some databases, emissions that occur after 100 years are identified separately, and their effect can therefore be considered separately. Databases may also have specific assumptions about the decay rates of biogenic material in landfill and the composition and capture rates for landfill gas, which may not relate to practice in the various Member States, or to current understanding. The practitioner should ensure that this aspect is not neglected. For example, organic materials should not be handled as though they were inert, as this might yield significant errors in the estimation of the fate of deposited material. The practitioner should ensure that the treatment of landfill and incineration processes is considered consistently with the datasets for the production of biogenic material (this should be the case if data are sourced from the same database). Module C4 covers the disposal of end-of-life construction material arising from the demolition of the building. The disposal of end-of-life material arising from the use phase (Modules B2–B5) is included in the individual module where the waste arises.Current landfilling rates and other disposal processes should be used to develop the scenarios for Module C4.The choice of LCA data for landfilling should correspond, as a minimum, to the different types of wastes (inert, non-hazardous and hazardous), although more detailed landfill models are available in many databases. In addition, the time period over which inputs/outputs should be inventoried from the point of disposal in landfill is 100 years [EN 15804 6.3.7]. For biogenic materials, it is of particular relevance to take account of the fate of the biogenic carbon when landfilled, considering the decay rate, the mix of carbon dioxide and methane produced from decay, and the landfill gas capture rate of the landfill. National assumptions for various materials and landfills vary widely.The extent to which biogenic carbon decays into methane at end of life also needs to be considered in LCA studies, although there is little consensus on exactly how much methane will be generated or released in an average landfill. In any event, the greenhouse gases released from biomass degradation will not be balanced by an equivalent amount of sequestered CO2, owing to the increased GWP of methane emission. National EPD programmes may prescribe landfill models, or the percentage of material that will be placed in landfill at the end of life.

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