From the earliest years of human civilization, our fellow global citizens have become increasingly enamored of cities. The Ancient cities of Mesopotamia and Egypt were later eclipsed by those of Athens and Rome and Constantinople (today’s Istanbul). Paris, London, Tokyo and New York City arose to take their ranks among the world’s largest aggregations of humanity. Before the end of the 19th Century, the planet’s greatest aggregations of humanity included such major urban areas as Los Angeles, Moscow, Mexico City, Buenos Aires, Sao Paulo, Osaka and Kolkata (Calcutta).
By 2008, just over half of our planet’s residents made their homes within cities. Before the year 2050 ends, it is likely that more than two thirds of all humans will occupy cities. Thus, over the past century, the major urban areas of the world have seen their total populations swell more than ten-fold. So how do we create sustainable cities for such a tsunami of human growth and sprawl, especially when many of the world’s largest cities may each contain more than 25 million eating, breathing, striving, drinking, energy-consuming, waste-producing individuals?
Despite what many green visionaries and urban utopians might propound, the answer may simply be to improve the cities we already have.
The best green foundation we can begin with is the city that is already built, no matter whether that city is New York or Detroit or Mumbai. That is because the existing city already has a huge store of ‘embedded energy’ — energy used in the past to pave its roads, run its power lines, construct its buildings, erect its bridges, channel its waste, and generate its municipal services. To start anew to create such significant essentials from scratch would consume vast amounts of energy and resources. We are far better off ‘tweaking’ what already exists.
And there are many ways to tweak existing cities. One of these is through recycling and re-purposing of existing city facilities. A shuttered big box retailer may be converted to a new, greener community center, as in North Collinwood, Ohio. An entirely new sustainable mixed-use community may rise from the rubble of a defunct urban airport, as at Stapleton in Denver. Historic warehouse structures may be converted to airy residential lofts and business offices, spiced by a collection of restaurants and bistros, as in Cleveland’s Warehouse District.
A second method is to employ infill development, in which the left-over interstices, alleyways and vacant lots — and in many cases, the remaining air rights — abutting existing structures are employed to create a more effective and efficient mix of uses and occupants. As the costs and values of core real estate in such cities as New York and London rise stratospherically, infill and overlay development become virtually the sole game to play. Such development is heartily green, for it increases the overall density of human interaction, thus simultaneously reducing the incremental environmental, energy and resource costs of that interaction.
Other methods of improving urban sustainability include correlating development to transit networks, thereby placing greater density of human interaction nearer the nodes and trunks of the all-essential transportation networks. When people can get themselves and their necessary goods and services to and from their homes and businesses more efficiently and at lower cost, overall sustainability increases.
Another significant tweak involves applying new technology to older structures and facilities. When every urban roof is either reflective or green, when every urban wall is green or solar-energy-absorptive or well-insulated, and when every dwelling unit makes use of reclaimed building products and water-saving fixturing, we will have gone a long way toward creating the sustainable city of the future.