Custom emission factors are used when standard emission factor sets such as the US EPA, UK DEFRA, IPCC, or other EF sets do not cover calculation needs. Using custom emission factors also allows for higher accuracy and detail of emissions from specific sources or activities.
How are custom emissions factors used for calculating GHG emissions from FEM/FDM?
Within FEM/FDM, a new set of optional questions were added that allow a facility to enter custom emissions factors (EF) for the following energy sources and their corresponding REFID:
- Purchased Electricity (enghgefelecpurchwquant)
- Chilled Water (enchilledwaterefquant)
- District Heating (ensourcedistrictheatingef)
- Purchased Renewables (ensourcepurchrenewef)
Below is an excerpt from the Energy Use & GHG 2023 Question Level Guidance for FEM2023, outlining how GHG emissions are calculated in the FEM.
The Higg FEM calculates Scope 1 and 2 GHG emissions based on the energy use values entered in the Energy section, as well as the refrigerant use listed in the Air section. Energy use values input into the FEM are converted to a common unit (MJ) and GHG emissions (CO2e) are calculated using the 100-year Global Warming Potential factors for each GHG in the IPCC 5th assessment report, including non-carbon GHGs.
In the FEM, location based emission factors are used by default when market-based emission factors are not provided by the user or required to be input into the FEM. Location-based and market-based emission factors are defined as follows:
- Location-based emission factors use the average emission factor for the energy/emission source (e.g. regional or national emission factors)
- Market-based emission factors consider contractual arrangements under which the organization procures power from specific sources (e.g. fossil fuels, renewable). These emission factors are typically specified in Energy Attribute Certificates (EACs), contracts such as a power purchase agreement (PPA), to purchase electricity from a specified generating facility, or provided as Supplier-Specific Emission Factors.
Custom emissions factors provided by the user are considered "Market-based emission factors" for these calculations.