Towards a green economy

demand for urban infrastructure. Cities can be structured to make use of green grid-based energy systems such as combined heat and power and micro-generation of energy as well as rainwater harvesting, access to clean water and efficient waste management. In short, effective urban planning and governance, as will be shown below, can have significant effects on sustainable urban lifestyles, making the most of urban critical mass and reducing individual patterns of consumption.

Despite a rich debate on the links between physical structure and energy use in cities, there is growing evidence that compact urban environments, with higher-density residential and commercial buildings (as opposed to low density, sprawl-like development) and a well distributed pattern of uses and an efficient, transport system based on public transport, walking and cycling reduce the energy footprint (Newman and Kenworthy 1989; Owens 1992; Ecotec 1993; Burgess 2000; Bertaud 2004). Research has shown that the so-called “compact city” model (Jenks et al. 1996) has lower per-capita carbon emissions as long as good public transport is provided at the metropolitan level (Hoornweg et al. 2011).

This relationship between urban form and energy performance also applies at the local, neighbourhood level. In Toronto, for example, a recent study found that car use and building-related emissions jumped from 3.1 tonnes of CO2

per capita in some inner-city areas to 13.1

tonnes in low-density suburbs located on the edges of the city (Van de Weghe and Kennedy 2007). While the evidence does not identify an ideal size or configuration for green cities, it suggests that highly concentrated urban systems produce public transport efficiencies, and that medium-sized cities tend to perform better than very large or very small cities when it comes to public transport and energy-related efficiency (Ecotec 1993; Bertaud 2004).

Many cities around the world have recognised such structural opportunities for green cities. Copenhagen, Oslo, Amsterdam, Madrid and Stockholm (EIU 2009), together with Curitiba, Vancouver and Portland in the Americas, have all prioritised compact urban development, creating walkable urban neighbourhoods supported by accessible public transport systems. Mumbai, Hong Kong and New York are high density cities where housing, commercial, retail and leisure are in close proximity, thus limiting the length of everyday trips (from home to work). In addition, they possess efficient and extensive public transport networks.

In

Mumbai, these patterns are related to high levels of poverty and overcrowding, while in Hong Kong and New York they combine considerable levels of energy efficiency with high living standards.

Clearly, there is an upper limit for urban densities to deliver environmental benefits without creating

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adverse social outcomes due to overcrowding and strained social infrastructure such as health or educational facilities. But if appropriately designed, cities can accommodate relatively high threshold densities even in low-income scenarios (and not just in highly serviced upper income environments). In their study on high density, low income housing in Karachi, Hasan, Sadiq and Ahmed (2010) concluded that net residential densities of up to 3,000 persons per hectare can be reached without compromising environmental or social conditions.

Technological potential Cities are incubators of innovation due to the close interaction of their residents and workers who benefit from the exchange of ideas and opportunities. In particular, they benefit from the concentration of diverse yet specialised skill-sets in research institutions, firms and service providers that can pilot and scale new technologies in an already highly networked environment. The OECD calculates, for example, that there are ten times more renewable technologies patents in urban than rural areas and that 73 per cent of OECD patents in renewable energy come from urban regions (Kamal-Chaoui and Robert 2009). The fast-growing cleantech clusters in Silicon Valley and the North East of England are both examples of

“nursery cities”, fostering innovative activity

(Duranton and Puga 2001). Silicon Valley business leaders have been working for years to leverage the valley’s innovation advantage in a green economy (Joint Venture Silicon Valley Network 2009). Section 4 illustrates how urban systems can be readily adapted to innovative technologies that support the transition to green cities, especially in the energy sector.

Urban synergy and integration potential Green cities can benefit greatly from synergies between their constituent parts. Recognising,

example, the interrelationship of energy systems and city fabric can lead to particular synergies, as pioneered by the Rotterdam Energy Approach and Planning (Tillie et al. 2009). In New York City, a new mechanism introduced by the Mayor combines the cleaning-up of light-to-moderately

contaminated

brown-field sites with urban re-development (City of New York 2010). Water-sensitive urban design, which helps to retain storm water in public spaces and parks, has increased the reliability of urban water supply in US and Australian cities (see Water Chapter).

An urban setting, which tends to support a diverse and compact pattern of production and consumption is

for

further advantageous to advance the notion of

“industrial ecology” (Lowe and Evans 1995). By optimising and synergising different industrial sectors and resource flows, outputs of one sector that become the input of