miércoles, 19 de mayo de 2010
How can sustainable urbanism mitigate city sprawl?
Sustainable urbanism bets, apart from other factors, for a way of living based in traditional cities, while urban sprawl is based on the American New Deal’s growth model. Urban sprawl requires an intensive use of automobile because social activities are fundamentally separated: work, housing and leisure are located in remote places from each other. However, sustainable urban design of the traditional city takes the compactness of urban applications, combining multiple activities in one building. In this way buildings can be used as shops and offices in their ground floors, and the followings as housing. The European historical city model, with its concentration of housing, shops and entertainment venues in the same area, reduces automobile use, which is the most unsustainable urban sprawl element.
Therefore, with a compact city car use and consequent energy expenditure will be lower. While activities are concentrated the height of the buildings increases, but a disproportionate increase in height will overspend materials and facilities whose production and use are highly polluting. That is why sustainable urban typologies should be based on a average density which not overwhelms the city. Again, we must look at the traditional city and its buildings with four/five floors and load bearing structures as an ideal model. Besides, load bearing wall structures are insulated and by using traditional techniques environmental impact is mitigated.
In an urban sprawl model density is very low and green spaces very large, but privately owned. In this way each owner has a small garden plot but can not enjoy great parks. But the compact mode of sustainable urban design can enjoy more public green areas. First, medium density blocks of housing could allow semiprivate courtyards that serve as a direct entertainment for each neighbourhood community. This model has been widely used throughout history and we can find examples in the blocks designed by Ildefonso Cerda for Barcelona Extension in 1859 and Seville old corral style communal homes, to name two Spanish cases. Second level is represented by squares, direct heirs to Roman Forum. Squares, arcades or not, organize the city around a historical landmark: church, market, palace, theatre… allowing social life around it, as the surrounding buildings themselves are also homes. It is essential a pedestrian plaza to allow free development of activities without fear of cars or their concentration when used as a parking. This square concept justifies an urban sustainability that seeks concentration of activities and allow great urban parks. These parks have their origins in the palace gardens which eventually opened to the public: a large green area for use and enjoyment of citizens who find the entertainment that don’t allow small gardens in an urban sprawl. These garden islands within a compact city allow a contact with nature without the need to use the car. Therefore avoids unnecessary trips by concentrating activities in a smaller place.
Another problem about urban sprawl is that for growing it needs to occupy a large amount of land and often these lands are forest or farms. Its transformation into urban areas implies the loss of fertile land and natural areas that could be exploded in a sustainable manner contributing to community development itself.
In conclusion, sustainable urban design can face urban sprawl by implementing a set of common principles to traditional European urbanism, moderate densification, public squares and public parks. In a compact city that combines several activities under one roof you need few time to travel from one point to another and also allow the guideline of each site vernacular architecture will allow a growth that will devour less land and thus mitigate the urban sprawl.