County of San Diego 2005/2006 Greenhouse Gas Emissions Inventory

Appendix D:
Community Inventory Methodology
This appendix expands on the description of methodology provided in Section 2, describing in more detail the data
sources and processes used to calculate emissions in the community inventory.
D.1 Overview of Inventory Contents and Approach
The community inventory describes emissions of the major greenhouse gases from the residential,
commercial/industrial, transportation, solid waste, and wastewater sectors. As explained in Section 2, emissions are
calculated by multiplying activity data—such as kilowatt hours or gallons of gasoline consumed—by emissions
factors, which provide the quantity of emissions per unit of activity. Activity data is typically available from electric
and gas utilities, planning and transportation agencies and air quality regulatory agencies. Emissions factors are
drawn from a variety of sources, including the California Climate Action Registry, the Local Governments
Operations Protocol, and air quality models produced by the California Air Resources Board (CARB).
In this inventory, all GHG emissions are converted into carbon dioxide equivalent units, or CO 2 e, per guidance in
the Local Government Operations Protocol (LGOP). The LGOP provides standard factors to convert various
greenhouse gases into carbon dioxide equivalent units; these factors are known as Global Warming Potential
factors, representing the ratio of the heat-trapping ability of each greenhouse gas relative to that of carbon dioxide.
The community inventory methodology is based on guidance from ICLEI’s draft International Local Government
GHG Emissions Analysis Protocol (IEAP), as well as methods utilized in the San Diego County Greenhouse Gas
Inventory produced by the University of San Diego’s Energy Policy Initiatives Center (EPIC)—which evaluated
emissions County-wide, both incorporated and unincorporated—and methods used in ongoing climate change
planning work at SANDAG.
D.1.1 Emissions Sources Included and Excluded
In general, local jurisdictions should seek to measure all emissions of the six Kyoto Protocol greenhouse gases 30
occurring within the jurisdictional boundaries. In practice, this level of detail may not be feasible for the local
jurisdiction. The table below describes sources included in this community inventory, followed by sources that
were excluded:
30 CO 2, CH 4, N 2 O, SF 6 , perfluorocarbons (PFCs) and hydrofluorocarbons (HFCs)
2005/2006 San Diego County Greenhouse Gas Emissions Inventory XV