For electricity, Portfolio Manager applies regional GHG factors to compute the GHGs associated with electric consumption (see page 11 of the GHG Emissions Tech Ref). Unlike the default fuel approach for direct emissions and indirect emissions from district systems, the approach for electricity is based on measured power plant data from utility owners and operators. For the U.S., these regional factors are determined using EPA’s Emissions & Generation Resource Integrated Database (eGRID). For Canada, these factors are obtained from Canada’s National Inventory Report –Greenhouse Gas Sources and Sinks in Canada.
For all other fuels, a national emissions factor is used:
For a more detailed explanation, see the GHG Emissions Technical Reference.