The sustainable city

For milleniums, since Jericho, Ur or Moenjodaro, the City had been dense and diverse place where people of all different social stratas walked, met and got to build together a culture, an economy...

Then, in the first part of the 20^th century, the advent of the automobile desintegrated the City: Frank Lloyd WRIGHT’s Broadacre City or Le CORBUSIER’s Ville Contemporaine were thought and planned at the exclusive scale of the automobile.

Surprisingly, these two most brillant architects had a very poor understanding of urban life, of the dense and diverse Traditional City as the cradle of social integration, of cultural and economic vitality...

Their “urban” models led to social and functional segregation, suburbian sprawl, housing projects and gated communities. They have canceled urban diversity and worsened air pollution by a major increase in the use of private cars.

The public urban space, as a convivial, social, cultural and economic meeting place has disappeared and general daily commuting has become the rule, with massive energy waste and air pollution.

The traditional City and its constant evolution

Jane JACOBS has precisely defined the conditions for urban diversity, in “The Death and Life of Great American Cities”.

Mixed use and a dense urban grid structure were the caracteristics of the Traditional City, over the centuries and the milleniums: it combined old and new buildings, offered a variety of paths, and it worked, people walked and met there, they integrated, they created thriving economies and cultures.

However, throughout the centuries, while retaining its diversity and its human scale, the Traditional City has constantly evolved, adapting to the local climates and following the technical requirements of the era.

Pompei is different from medieval Rouen, which is different from baroque Berlin or from 19th century Manhattan.

The 21^st century Sustainable City should not only reintroduce urban diversity: it should also deal fully with the new challenges we are now facing.

The challenges we are now facing

We are witnessing a major surge in urban population all over the world: 5 billion people will live in cities by 2030, as established by a U.N. report released in June 2007.

At the beginning of the 21^st century, we are facing a major challenge: global warming caused by greenhouse gas and carbone dioxide emissions in the atmosphere.

A major part of the emission of greenhouse effect gases is caused by massive urban daily migrations (automobile exhausts), but also by house heating and air conditioning, in order to fulfill the obvious research of thermal comfort for the city dwellers.

Against the segregated and desintegrated present urban sprawl situation, a mere return to the urban forms of the 19^th century is therefore not sufficient.

The requirement of our times of massive urbanisation is not only to reintroduce the diversity and human scale of the 19^th century City, but also to integrate fully the renewable energies (passive solar design, etc...) which will inevitably lead to new urban forms.

Energy independence

Another very important challenge is to minimize the dependency of the democracies over oil imported from totalitarian countries, with undemocratic and backwards regimes financing terrorism and violating human rights.

In the long run, a prolonged dependency on such oil would inevitably reinforce the worst threats on democracy and mankind, worldwide.

Are the electric car or biofuel the answer?

The generalization of the electric car would have its drawbacks: nuclear waste accumulated in nuclear power plants is dangerous and difficult if not impossible to manage in the very long run (in fact, thousands of years...).

And, in countries or regions where the electricity is generated by coal or fuel power plants, the electric car would be very harmful for the environment.

To produce bioful at a very large scale would deprive mankind of vital agricultural ressources and spread hunger.

The only purpose of these wrong solutions seems to be to postpone and possibly jeopardize the necessary evolution of industrial strategies towards progressive replacement of the present massive production of individual cars and homes in favor of frequent and convenient public transportation (trains, buses, ..) and attractive Sustainable Cities.

The urbanism of tomorrow (La Cité du Futur)..

..has often been outlined by designers like KUROKAWA, JONAS or QUARMBY with radically futuristic and improbable forms, floating in the air or on the water, like sets of gigantic umbrellas or myriads of pods hanging from endless poles, where people would seem to be expected to live like insects rather than like human beings.

In fact, the “City of tomorrow” will hopefully just be instead another development of the Traditional City, still a meeting place allowing encounters and cultural and economic exchanges, still a place where people will enjoy walking, just like they enjoyed walking in Pompei, two thousand years ago.

The only difference will be that the “City of tomorrow” will be designed so as to welcome a world population which has increased tremendously, and at the same time, protect the environment:

- by the appropriate use of solar energy and passive solar architecture on a large urban scale,

- and by a dense mixed use urban design which will free the city dwellers from compulsory, costly and detrimental daily use of private cars.

Integration of renewable energies in a dense mixed-use urban form

An important amount of research and experimentation regarding solar and “bioclimatic” architecture has so far concerned mostly detached houses, situated primarily in suburban or isolated context.

For detached houses in a low density area, access to low winter sun is not a problem.

However, urban sprawl leads to a major increase in the use of individual cars, therefore simply displacing pollution, if these houses are using renewable energies, from emissions caused by house heating to automobile exhausts, with no overall gain as far as protection of the environment is concerned.

In order to obtain a real environmental gain, it is therefore necessary to integrate a full use of renewable and clean energies into dense and mixed use urban context, where people will be naturally enticed to walk or bike as often as possible, or use public transportation instead of private cars.

However, in a dense urban context, access to (lower in the sky) winter sun and avoidance of masks is more problematic than for detached houses.

This requires a specific research on which we have worked extensively.

We first presented our findings: “Le Bioclimatique en Milieu Urbain Dense”, at a 1993 seminar organised by the International Solar Energy Society, and ADEME, in Sophia Antipolis, France.

We then, over the years, considered how these researches would apply to several specific sites:

- « Seine-rive-gauche » district. Paris, France

- « Le Dock des alcools », Ris-Orangis, near Paris, France

- “Northern style housing complexe” in Aomori, Japan

- “Lochend-Butterfly” area, Edinburgh, Scotland

The Organic Solar City

In place of a succession of mono-functional buildings, all of the same height, and therefore denying each other access to winter sun, it is a fluid, organic and evolutionary configuration, designed to receive solar light and heat naturally (Passive solar design...).

By superimposing the diverse and simultaneous urban functions characterizing a living whole, and combining them organically, one can at last optimize their relation to public space and sunshine, and create a diversified urban environment on a human scale, with an effective limitation of air pollution.

It will also definitely be a green city, with urban parks, tree lined avenues and streets, and stepped housing with conservatories and private gardens facing the sun, on all floors.