title: A demand-centered, hybrid life-cycle methodology for city-scale greenhouse gas inventories.
abstract: Greenhouse gas (GHG) accounting for individual cities is confounded by spatial scale and boundary effects that impact the allocation of regional material and energy flows. This paper develops a demand-centered, hybrid life-cycle-based methodology for conducting city-scale GHG inventories that incorporates (1) spatial allocation of surface and airline travel across colocated cities in larger metropolitan regions, and, (2) life-cycle assessment (LCA) to quantify the embodied energy of key urban materials--food, water, fuel, and concrete. The hybrid methodology enables cities to separately report the GHG impact associated with direct end-use of energy by cities (consistent with EPA and IPCC methods), as well as the impact of extra-boundary activities such as air travel and production of key urban materials (consistent with Scope 3 protocols recommended by the World Resources Institute). Application of this hybrid methodology to Denver, Colorado, yielded a more holistic GHG inventory that approaches a GHG footprint computation, with consistency of inclusions across spatial scale as well as convergence of city-scale per capita GHG emissions (approximately 25 mt CO2e/person/year) with state and national data. The method is shown to have significant policy impacts, and also demonstrates the utility of benchmarks in understanding energy use in various city sectors.
authors.affiliation: Department of Civil Engineering, University of Colorado Denver, Denver, Colorado, USA. anu.ramaswami@cudenver.edu
authors.forename: Anu
authors.initials: A
authors.lastname: Ramaswami
authors.forename: Tim
authors.initials: T
authors.lastname: Hillman
authors.forename: Bruce
authors.initials: B
authors.lastname: Janson
authors.forename: Mark
authors.initials: M
authors.lastname: Reiner
authors.forename: Gregg
authors.initials: G
authors.lastname: Thomas
mesh_terms: D005740:Gases / Q000032:analysis*; D017752:Greenhouse Effect; D014481:United States; D014484:United States Environmental Protection Agency
chemical_list: D005740:Gases