Every five years, DVRPC performs a regional energy use and CO2 outputs inventory of the Greater Philadelphia region. The inventory looks at energy use and CO2 outputs associated with the residential, commercial, transportation, and other sectors of the region. The inventory does not include energy use or CO2 outputs associated with the production of imports to the region, other than electricity. CO2 outputs are generally reported in metric tons of carbon dioxide equivalent (CO2e) units. 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 GHGs—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.