Every five years, DVRPC performs a regional energy use and heat-trapping gases inventory of the Greater Philadelphia region. The inventory looks at energy use and heat-trapping gases associated with the residential, commercial, transportation, and other sectors of the region. The inventory does not include energy use or heat-trapping gases associated with the production of imports to the region, other than electricity.

Heat-trapping gases are generally reported in millions of metric tons (MMT) of carbon dioxide equivalent (CO2e). This measure accounts for other gases, such as methane and nitrous oxide, as well as hydrofluorocarbons and perfluorocarbons, which are emitted in smaller amounts—but are more powerful heat-trapping gases—than carbon dioxide (CO2).

Energy production source data is reported from the U.S. Environmental Protection Agency, Emissions & Generation Resource Integrated Database (eGRID). And weather trends data are from the National Oceanic & Atmospheric Administration's National Centers for Environmental Information.