Linking the urban form to environmental and health impacts with a life-cycle approach
Today, over half of the world’s population lives in urban areas, which account for the heaviest consumption of natural resources and significant generation of emissions and waste. Urban planning and design play a central role in promoting sustainable urban development by evaluating and guiding changes in the urban form. Environmental assessments of urban areas are needed to anticipate how different urban form characteristics can affect the environmental performance of urban areas and help urban planners and decision-makers to identify and design strategies toward sustainable development. However, urban areas are complex systems and challenging to evaluate for many reasons: assessments are multidisciplinary in nature; many approaches and indicators can be used to evaluate environmental performance; data requirements can be large; and there are many limitations and uncertainties. There is a need for systematic, integrated and objective frameworks to model, evaluate and compare alternative strategies and scenarios that can promote sustainable urban development.
The overall goal of this dissertation is twofold: to provide insight on key linkages between urban form and environmental impacts of urban areas; and to address critical issues in the application of life-cycle assessment (LCA) to urban systems. The research investigates environmental and health impacts associated with residential buildings and transportation, examining the interaction with the urban form. The research evaluates modeling and parameter choices in the LCA of buildings, the potential significance of user commuting requirements, the comparative environmental and health assessment of commuting modes, and how to adequately address exposure and health effects associated with traffic-related air pollutants
within a LCA framework. These issues are addressed using four case studies drawn from the Lisbon (Portugal) area.
The results show that larger dwelling floor area per occupant can significantly increase energy demand and greenhouse gas (GHG) emissions associated with residential buildings, due to higher construction, use phase and retrofit requirements, but different metrics can provide contrasting results. Energy and GHG emissions associated with commuting can exceed those of residential buildings if housing is located in a car-dependent location. Environmental impacts of different urban transportation modes vary significantly, and future shifts in transportation mode or technology can cause trade-offs between impact categories, e.g., a shift to electric vehicles may decrease GHG emissions and health impacts associated with traffic-related air pollutants, but increase freshwater eutrophication. In addition, it is important to consider local environmental and health impacts, particularly in areas near major roads that are densely populated. On a methodological level, results show the importance of applying a life-cycle perspective in the environmental assessment of urban areas, the varying results and implications of using different impact indicators and metrics, the significance of using system boundaries that encompass the greater urban area in order to avoid missed or shifted impacts, and the need for spatially resolved analyses that more accurately estimate local environmental and health impacts.
Drawing on the approaches and results of this research, recommendations are provided for the evaluation of environmental and health impacts associated with urban areas and the urban form. The proposed approaches extend and can improve the application of LCA to urban systems, by addressing a wide variety of impacts and key methodological issues, identifying potential improvement opportunities, and revealing unintended impacts and trade-offs. The methods can be applied in other cities and different settings, since they use mostly statistical data from national or international sources. The findings obtained for Lisbon may be generalizable since Lisbon’s urban form characteristics and development trends are common to those in many other cities; however, local and site-specific assessments are recommended. The dissertation shows the feasibility of integrating urban and transportation planning in a LCA context that considers environmental and health goals, and it suggests the benefits that can be attained by using this type of tools to develop more sustainable urban forms.
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|Institution||University of Coimbra|