Urban sustainability

London has experienced great changes in its population which in turn has had implications for the land area occupied and needs for inputs and outputs – the basis for any system. Sustainability depends on the nature and balance of the system. If the system grows in total numbers, it will require more inputs and inevitably produce more outputs. If the system reduces or increases in numbers of working age group, other issues will ensue.

© Transport For London

London comprises the following areas:

Inner London
Both inner and outer boroughs are within the administrative and political area of London. Inner London includes the boroughs of the City, Greenwich, Westminster and Camden. Between 1901 and 1981 inner London's population declined in the form of decentralisation to outer suburbs and people seeking lower density housing and a cleaner environment. This was encouraged by government policy to disperse people and jobs beyond the green belt, established in the 1930s to contain sprawl. After 1991 this trend has reversed as regeneration schemes have encouraged more investment and better quality of environment, especially in central and inner London.

Outer London
Outer London includes the suburban developments such as the boroughs of Bromley, Richmond and Barnet. Outer London developed with the growth of the railways and the underground, which subsumed rural areas around London as the conurbation developed. Between 1941 and 1991, the population of outer London declined as people moved further out into the southeast.

Greater London
Greater London is the sum total of inner and outer London. It is the main administrative area now presided over by the Mayor.

Metropolitan Area
This extends beyond the green belt and is the functional area of London. Metropolitan London is the main geographical region based on the 'travel to work' area.

The graph below illustrates the changes in total population in these areas, which London has experienced since 1891.

© Corporation of London

It is critical for a sustainable city to reach a positive balance. Inputs into a city include people and goods, water and energy. Outputs again include people, and goods as well as unwanted products such as sewage, air pollution and refuse.

Sustainability can be measured by having fewer outputs than inputs – for example when efficient recycling and waste reduction is achieved.

The following diagram shows how the spatial area of London, and hence its demands via inputs and outputs, have increased dramatically over time.