Methods

Environmental Benchmarking

Life cycle assessment (LCA) (ISO 2006) is a tool for the systematic compilation and evaluation of the environmental aspects and the potential environmental impacts of products systems throughout their life cycle, from raw material acquisition through use until final disposal (UNEP/SETAC 2012). In this sense, the environmental benchmarking of multiple alternatives for urban fabric planning was conducted by reviewing LCA studies on their environmental impacts. To do so, different constructive solutions for sidewalks, pavements, and gas, water and wastewater networks were compared in terms of global warming potential (GWP; kg of CO2 eq.) (IPCC 2007).

The Urban Fabric

Multiple elements compose the urban fabric where daily urban life is supported. In this study, the authors considered the paved skin (sidewalks, road pavement) and the subterranean pipelines that supply basic services (gas, water, wastewater). Figure 22.1 displays a scheme of the urban fabric system. The functional unit of the assessment is a 1 × 8 m street section in a time frame of 50 years, representative of a European medium-sized city. In particular, the scenario considers a street profile located at the city centre where light-weight traffic and pedestrian areas are preferential. Superficial structures such as benches or streetlights were excluded.

Environmental Profile of Urban Fabric Elements

The following section describes the environmental profile of multiple design options for the urban fabric. Once compared, the best practices are assembled to show an optimized design of the paved skin (sidewalks, road pavement) and the subterranean pipelines that supply basic services (gas, water, wastewater) from an environmental point of view.

Fig. 22.1 The urban fabric: profile of the paved skin and subterranean pipelines under assessment

Table 22.1 Global warming potential (GWP) (kg of CO2 eq.) of different pavement solutions for a functional unit of 1 m2 in a time frame of 50 years and renovation scenarios

Pavement designs

Reference service life

High renovation rate (lifespan: 15 years)

Low renovation rate (lifespan: 40 years)

Concrete top-layer

79

129

82

Granite top-layer

109

221

117

Asphalt top-layer

84

84

Note: The reference service life of sidewalks designs are 15 years for asphalt and 45 years for concrete and granite

 
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