Whole life carbon
To acquire an overall understanding of a material's or a building project's total carbon impact it is necessary to assess carbon emissions across the entire/whole life cycle.
The definition of Whole life Carbon (WLC) as stated by the Low Energy Transformation Initiative (LETI) is:
Whole Life Carbon (WLC) emissions are the sum total of all asset related GHG emissions and removals, both operational and embodied over the life cycle of an asset including its disposal (Modules: A1A5 Upfront; B1-B7 In Use; C1-C4 End of Life). Overall Whole Life Carbon asset performance includes separately reporting the potential benefit from future energy recovery, reuse, and recycling (Module D).
The life cycles of a product or building are grouped as follows:
Product stage comprises emissions incurred through raw material supply (A1), transportation (A2) and manufacture (A3) and is sometimes referred to as Cradle-to-Gate emissions.
Construction process stage comprises the transportation from manufacturer to site (A4) and the emissions associated with construction (A5). Together with product stage these combined stages (A) are sometimes referred to as Cradle-to-Practical Completion or Upfront Embodied Carbon.
Use stage (B) includes emissions related to multiple aspects of use of an asset. This includes Use (B1); Maintenance (B2); Repair (B3) and Replacement (B4); Refurbishment (B5) Operational Energy use (B6) and Operational water use (B7).
End of Life stage (C) relates to emissions associated with the Demolition (C1) Transport (C2); Waste processing (C3) and Disposal (C4)
Cradle-to-Grave emissions are Stages A, B and C together.
Whole Life Carbon assessment also includes Module D, which is currently defined as the benefits and loads beyond the systems boundary of the project. This relates to the reuse, recovery and recycling potential of the elements of an asset and is sometimes referred to as the circular economy module.
At a product or material level WLC emissions are represented by the Global Warming Potential (GWP) parameter in an Environmental Product Declaration (EPD). With figures provided at each of the relevant stages.