Article

A Demand-Centered, Hybrid Life-Cycle Methodology for City-Scale Greenhouse Gas Inventories

Department of Civil Engineering, University of Colorado Denver, Denver, Colorado, USA.
Environmental Science and Technology (Impact Factor: 5.33). 10/2008; 42(17):6455-61. DOI: 10.1021/es702992q
Source: PubMed

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.

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    • "Therefore a consumption-based approach to urban environmental sustainability is suggested to add to the possibilities for influencing global issues through local actions (Holden and Norland 2005;Neuman 2005;Eaton et al. 2007;Hoornweg et al. 2011). The logic of a consumption-based evaluation is that urban areas are considered to be responsible for all the direct and indirect environmental impacts of all the products and services the inhabitants consume, regardless of where geographically the environmental impacts take place (Ramaswami et al. 2008;Weber and Matthews 2008;Kennedy et al. 2010). This article discusses the rationale of current urban development policies and practices in their push for the reduction of environmental load as it relates to a consumption-based idea of urban environmental sustainability . "

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    • "Other organizations have constructed accounting systems to deal with different scales, including the GRIP system for the European Metropolis (Carney et al., 2009), the ICLEI system (mentioned above) for cities, and the World Resources Institute/World Business Council on Sustainable Development system for enterprises (WRI/WBCSD, 2009). Based on the research that led to these systems , Ramaswami et al. (2008) accounted for the carbon emission of Denver at three scales, and distinguished between carbon emission inside and outside of the city's boundary. Although the focus and objectives differed among these organizations, they all provided empirical coefficients that can be used in carbon accounting and that have greatly reduced the difficulty of such accounting. "
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