Life Cycle Management Applied to Urban Fabric Planning
Xavier Gabarrell, Joan Rieradevall, Alejandro Josa, Jordi Oliver-Solà, Joan Manuel F. Mendoza, David Sanjuan-Delmás, Anna Petit-Boix, and Esther Sanyé-Mengual
Abstract Due to the rapid urbanization and the large contribution of cities to the global environmental impact, urban policies integrate sustainability in the public space design. Current literature has accounted for the environmental impact of the main elements of the urban fabric, although studies have dealt with them individually. This chapter aims to optimize the environmental performance of the urban fabric for supporting planning processes, based on existing life cycle assessment (LCA) data of the main elements of urban fabric: sidewalks, pavements, and the gas, water and wastewater networks. Material selection and lifespan are key issues in the environmental profile of the paved skin, while the installation accounts for the greatest share of the burdens in subterranean networks. The best design consists of concrete sidewalks, asphalt pavements, HDPE (high density polyethylene) gas pipes, PVC (polyvinyl chloride) water pipes, and concrete sewer pipes. Pavements and sidewalks are the most contributing elements to the overall environmental burdens of streets.
Keywords City developments • Life cycle assessment • Life cycle management
• Life cycle thinking • Pavements • Sidewalks • Sustainability
More than 50 % of world's population is concentrated in cities, although they occupy less than 2 % of the Earth's surface. Because of the intense activity of cities, which play an essential role in the global socio-economic development, they consume over 75 % of the world's resources, between 60 % and 80 % of total energy, and are responsible for approximately 75 % of global greenhouse gas (GHG) emissions (Ash et al. 2008; Kamal-Chaoui and Robert 2009; Pacione 2009; UN Population Division 2010; European Union 2011; Lazaroiu and Roscia 2012). Environmental awareness of the urban metabolism has raised due to the rapid urbanization patterns. As a result, policy and planning highlight the importance of promoting environmental strategies that increase the sustainability of cities (UN 2013).
Within cities, public spaces play a key role in supporting daily urban life. According to UN-HABITAT (2013a, b, c, d), four main issues might be considered. First, streets may become a matrix which increases the urban connectivity between people and activities thereby making mobility more efficient. Second, the street pattern hosts urban basic services, such as water supply. Third, public space is a key element for the cultural and political dimensions of cities. Finally, street design might enable the pedestrian and road mobility in a safe manner. Thus, streets are composed of multiple elements from diverse natures that satisfy the different functionalities of the public space (UN-HABITAT 2014).
The urban fabric is in constant change because of new city developments, maintenance and partial renewals due to the intense urban activity. The World Wide Fund for Nature (WWF) accounted for $350 trillion of expenditure on urban infrastructures in the coming decades. Assuming business-as-usual (BAU) conditions, these projects would contribute to around 465 Gt of GHG emissions (WWF 2008). Then, if no environmental criteria are applied in the urban planning design (i.e., aesthetic or economic criteria are prioritized), the global environmental burdens of cities can dramatically increase. Furthermore, the consideration of all the life cycle stages to account for the environmental burdens of urban elements is basic for understanding their environmental performance, as demonstrated by Oliver-Solà et al. (2009a, b, c), Mendoza et al. (2012a, b), Petit-Boix et al. (2014), Sanjuan-Delmás et al. (2014).
The general aim of this chapter is to incorporate the life cycle thinking approach into the design of the urban fabric for supporting planning processes, thereby optimizing the environmental performance of cities. The objective is to identify the best environmental practices by comparing existing LCA data of the main elements of the urban fabric (sidewalks, pavements, and the gas, water and wastewater networks) and to integrate these practices into the environmental impact accounting of the entire street profile.