Over the past several years, Mayor Richard M. Daley has been putting forth a vision for the future of Chicago that would have made the city's old ward bosses blanch. In a town once best known for the railroad and the stockyard, the smokestack and the Board of Trade, the mayor is saying that he wants to make Chicago the "greenest city in America."

Whether the Chicago of your imagination was shaped by Carl Sandburg, Saul Bellow, or the blues; by bustling LaSalle Street, busy O'Hare or pastoral Wrigley Field, Chicago has not been widely known as a green city. But Mayor Daley does not believe that history is destiny. Since taking office in 1989 he has been working to restore Chicago's environment with programs that turn the conventional notion of the big, industrial city on its head. Now Chicago sits on the edge of a new frontier, ambitious and energetic as ever. As Department of the Environment Commissioner Marcia Jimenez said: "We might even become the greenest city in the world."

The mayor got started by inviting trees back into town. Sowing saplings block-by-block, neighborhood-by-neighborhood, Daley's administration has now planted more than 300,000 trees throughout Chicago. Other long-term projects are devoted to restoring Chicago's 29-mile Lake Michigan shoreline and creating a 3,000-acre wetland preserve within the city limits. An industrial restoration program, meanwhile, is cleaning up hundreds of acres of land contaminated by heavy industry, making the City's brownfield redevelopment effort the largest in the United States.

With each of these programs contributing to a resurgence of health and natural beauty, Chicago could probably begin to wear the "green city" mantle without doing much more. But Mayor Daley understands that a 21st century metropolis must go beyond beautification and make environmental initiatives an integral part of a long-term strategy for growing economic and social health. To that end, says DOE First Deputy Commissioner, David Reynolds, the City is working "to bring industry back to Chicago while also revitalizing local ecology." The mayor is committed, he says, to "making the city a national model of how industry and ecology can exist side-by-side."

Sounds great. And Chicago's not just talking the talk. Mayor Daley's "greenest city in America" idea has recently been reinforced by the City's announcement that it had signed an agreement to buy 20 percent of its electricity-for schools, libraries, subways and streetlights-from renewable sources of power by 2006. That's the largest purchase of renewable power in the United States. And because the power must come from within the state of Illinois, it is spurring the local development of renewable energy technology. Indeed, some renewable energy companies, such as the solar panel manufacturer Spire, have moved their headquarters to the Chicago Center for Green Technology, a newly renovated, environmentally intelligent facility built on a restored industrial site. Spire is already supplying Chicago with locally manufactured solar panels, which the City has installed on a number of buildings, including the Field Museum, the Mexican Fine Arts Museum and the Art Institute of Chicago.

This is not your father's Windy City.

A Green Constitution
If Chicago's streets are lined with trees, it's power increasingly renewable, and its industries and institutions tapping into the benefits of green technology, has the city not already arrived as a national environmental leader? Well, yes. But to insure that its environmental initiatives last, the City has realized that it needs a set of enduring principles to guide decision-making over the long haul. The greening of Chicago can only be sustained, City officials believe, if each strategic choice makes ecological, social and economic sense, not just during the Daley administration but well into the future.

David Reynolds put it this way:

"We have been saying that we are going to be the greenest city in America. But to truly become a thriving green city we need to carefully define what that means and what we should be striving for, day-by-day and year-by-year. No city in the United States has really gotten this right yet, and we believe that part of the problem has been that no American city has developed a set of guiding "green" principles-akin to the timeless principles of the Constitution-that describes its ideals, sets its course and defines its means. That's what we are doing in Chicago. And we hope the principles we develop become so well known and so well understood that they define how we operate as a city government for the next one hundred years."

As Chicago's environmental initiatives picked up steam behind the mayor's "greenest city" rallying cry, Daley and former DOE Commissioner, Bill Abolt (now in the City's Budget Director), hired William McDonough + Partners to help draft its new principles. Working closely with the DOE and other government agencies, our community design team is crafting a set of design guidelines-The Chicago Principles-that will serve as a reference point for the City as it develops a holistic, integrated plan for the greening of Chicago.

Like the Constitution, the Chicago Principles will be based on timeless values. In essence, they will extend the rights and responsibilities of a democratic government and its citizens into the realm of nature and design. For example, in 1992 when my colleague, the German chemist Michael Braungart, and I developed design principles for the City of Hannover, Germany, for the 2000 World's Fair, we crafted nine declarations with the City that reflected its commitment to sustainability. The Hannover Principles included declarations such as:

• Insist on the rights of humanity and nature to co-exist in a healthy, supportive, diverse and sustainable condition.
• Recognize interdependence. The elements of human design interact with and depend upon the natural world, with broad and diverse implications at every scale. Expand design considerations to recognize even distant effects.
• Eliminate the concept of waste. Evaluate and optimize the full life-cycle of products and processes, to approach the state of natural systems, in which there is no waste.
• Rely on natural energy flows. Human designs should, like the living world, derive their creative forces from perpetual solar income. Incorporate this energy efficiently and safely for responsible use.

If these principles seem serious and demanding, well, they are. The language is meant to suggest the rigor required to live up to them. At the same time, we have found that striving to recognize interdependence or rely on natural energy flows in everything we do-from designing buildings to community plans-turns out to be inspiring and extraordinarily satisfying as well as a lot of fun.

And it yields a very unconventional perspective on urban design. Most responses to today's environmental woes aim to limit the impact of human activity by minimizing pollution and waste. We'd rather eliminate waste altogether and create delightful, healthful places designed to ultimately generate more energy than they consume, like the solar and geo-thermal powered facility we are building at Oberlin College. There, students and teachers not only reap the benefits of clean renewable energy, they also enjoy copious daylight, fresh air and a landscape alive with trees and flowing water. The building even teaches how nature works. One can see the workings of wetlands, for example, by observing how a series of botanical gardens filter the building's wastewater. Indoors and out, the building and its grounds celebrate both human creativity and the abundance of the natural world.

In Chicago our goals are the same. With the City, we will be drafting principles that encourage planners, developers, engineers and architects to pursue designs that create more positive effects, not fewer negative ones. This goes for everything from transportation systems to factories to commercial products to neighborhood plans, all of which can be designed to enhance the city's economic, environmental and social health. How? By following principles derived from nature's laws. In the city, as in the countryside, sustainable design is grounded in the rules of the natural world.

Design and Nature's Laws
Design for sustainability has its roots in the desire to discover fitting ways for humans to inhabit the landscape. As designers, we study the landscape of a particular place by assessing its natural systems: its landforms, hydrology, vegetation, and climate. We tap into natural and cultural history; investigate local energy sources; explore the cycles of sunlight, shade and water; and observe the lives of local fauna, flowers and grasses. As we carefully explore the landscape we might ask: How does the water flow down the hillside and through the valley? How did indigenous people build and live here? What local trees provide abundant shade? From which direction do cooling breezes flow? Out of these investigations comes an "essay of clues," a map for developing healthy and creatively interactive relationships between our designs and the natural world.

This emphasis on the way nature works results in buildings and communities that sustain and enhance the qualities of the local landscape. The "living roof" we designed for a corporate office building in San Bruno, California, for example, creates acres of habitat for local birds and grasses. When birds fly overhead they don't see a flat, ugly rooftop broiling in the sun, they see a rolling, flowering landscape that looks like home. In Chicago, the green roof we helped design for City Hall is covered with mostly native vegetation, which offers urban habitat to the butterflies and birds of the region. Not incidentally, City Hall's green roof absorbs storm water run-off and insulates the building from the hot sun, provides relief from the urban heat island effect.

In every landscape, nature is our guide. Natural forces express themselves differently from place to place, but as we have worked on projects and products worldwide, we've identified three key principles that allow us to apply our knowledge of natural systems to human designs. We imagine these principles may have a role in shaping Chicago's future.

Waste=Food. The life cycle of every organism contributes to the health of the whole. A fruit tree's blossoms fall to the ground and decompose into food for other living things. Bacteria and fungi feed on the organic waste of both the tree and the animals that eat its fruit, depositing nutrients in the soil in a form ready for the tree to take up and convert into growth. In these perpetual cycles-which we call cradle-to-cradle cycles-one organism's waste becomes food for another.

Designs modeled on these cradle-to-cradle cycles eliminate the very concept of waste. A textile we designed, which is woven from wool and ramie and processed with completely safe chemicals, can be tossed on the ground to nourish the soil when it wears out. At the Swiss mill where the fabric is produced, the trimmings serve as garden mulch and the water leaving the factory is as clean as the water flowing in. Synthetics like plastics and metals can flow in cradle-to-cradle cycles too. They can be designed for continual reuse as high-quality materials for industry. A new recycling process, for instance, allows carpet manufacturers to reuse nylon fiber perpetually. Materials and processes such as these can make manufacturing a restorative act and they will power Chicago's emergence as a green manufacturing hub.

Use current solar income. Living things thrive on the energy of the sun. Trees and plants manufacture food from sunlight, an elegant, effective system that uses the earth's only perpetual source of energy income. Buildings can tap into solar income using direct solar energy collection or passive solar processes such as daylighting, which makes effective use of natural light. The winds, too, can be tapped. Winds are thermal flows fueled by sunlight and, along with the sun, can generate enough power cost-effectively to meet the energy needs of entire cities, and indeed, entire nations.

As we have seen, Chicago is already using the power of the sun and the wind. Yet even as it purchases 20 percent of its energy from these sources it has only begun to tap the incredible power of the driving winds of the Great Lakes and the Plains. Encouraging the large-scale development of wind power, and fully integrating solar and wind into Chicago's energy infrastructure will make the City a world leader in the renewable energy industry. Clean power, economic development, thousands of jobs-all by using the energy of the sun.

Celebrate diversity. Healthy ecosystems are complex communities of living things that have developed diverse responses to their surroundings. They provide many models for design. Architects and planners, applying a diversity of design solutions, can create and restore buildings, industries, landscapes and neighborhoods that fit elegantly and effectively into a variety of niches.

Why not a diversity of healthy landscapes in Chicago? Imagine inner-city streams, lakes and marshes becoming home to local endangered species like the black-crowned night heron and the yellow-headed blackbird. Imagine lively street life and prosperous small businesses in neighborhoods blessed with the shade of trees. Imagine restored industrial sites that generate economic prosperity while creating habitat alongside river corridors.

One can see this vision emerging in Chicago and elsewhere in the industrial Great Lakes. Consider, for example, the restoration of the Ford Motor Company's River Rouge plant in Dearborn, Michigan. There, on a formerly shopworn industrial site, newly planted trees, a ten-acre living roof, and a series of constructed wetlands and swales are restoring soil, creating habitat, and revitalizing the landscape while effectively filtering stormwater runoff for $35 million less than conventional technical methods. When design tunes into biodiversity, even heavy industry can be a regenerative force.

The City as Organism
While nature's laws shape our sense of cities, they don't force us into a static view. We see each city, and we see Chicago, as part of a dynamic ecosystem, a singular evolutionary matrix. And we see the future of the City as an ever more harmonious and creative participation in the surrounding landscape. Claude Levi-Strauss put it well when he described the city as the place where "nature and artifice meet."

"A city is a congestion of animals whose biological history is enclosed within boundaries, and yet every conscious and rational act on the part of these creatures helps to shape the city's eventual character. By its form as by the manner of its birth, the city has elements at once of biological procreation, organic evolution, and esthetic creation. It is both a natural object and a thing to be cultivated; individual and group; something lived and something dreamed."

Cities are made. One can look at a metropolis like Chicago and get the sense that it has always been there. Yet in 1830s Chicago, as William Cronon has written, "one did not have to walk more than a few minutes to be out on the prairie." Just 60 years later booming, urbane Chicago hosted the famous Columbian Exposition.

Cities are designed. The tree-lined boulevards and elegant storefronts of Paris are not the result of lucky happenstance but of an ambitious 19th century renovation that remade the city from the sewers to the rooftops. It is no coincidence that Paris has remained a cultural capital in spite of the mercurial fortunes of France.

Cities are organisms. They have metabolisms. They are linked to their regions through complex networks, both natural and cultivated, that circulate biological nutrition-food, wood, fiber, water-and technical nutrition-the hardware and software of the 21st century. These flows of nutrients are the twin metabolisms of the living city. If we are to make our cities truly sustaining we need to take this literally, not just as the beautiful and moving idea about cities that Levi-Strauss blessed us with, but as a literal, strategic truth that informs all of our designs.

What might this look like? What might Chicago be in 2020?

Nutrient Flows: A New Relationship Between City and Region
One thing seems clear about the future of Chicago: it will be, as it has always been, a regional hub. But what kind of hub? Cronon explains in his history of Chicago, Nature's Metropolis, how the city's grain, meat, and timber markets transformed the landscape of the West. Railroads, grain elevators, stockyards, and wheat farms stretching from Illinois to the Rocky Mountains all emerged in relation to Chicago's markets. All of these "landscapes of production" created a "gritty web of material connections" that fed, clothed, and sheltered the people of Chicago and its hinterland. But not without cost. The harvest of commodities from the woods and prairies, and their processing in the city, created degraded landscapes on both ends of the rails that carried nature to market. As we saw in the floods of 1998, the Great Plains are dramatically losing their ability to hold water and the great flush of toxins has created a 100 square mile area of the Gulf of Mexico known by scientists as the Dead Zone.

There are other, more positive ways in which Chicago might be a hub. What if Chicago became a different sort of "Nature's Metropolis," a city bound to its region by healthy, reciprocal relationships in which nutrition flowed both ways? From the countryside would come biological nutrition and from the city, technical nutrition.

Supporting a regional organic food system would be a good place to start. In this new model, Chicago's markets could support the rebirth of the American prairie. Organic farming works with natural cycles of water and natural flows of nutrients. By returning the carboniferous material to the soil it heals the land and the watershed, a dire need in a region in which conventional farming is exhausting the earth. As Chicago's markets for organic food grow, the city would become an ever-stronger catalyst for the restoration of economic, social and environmental health in the rural Midwest-not to mention the health of Chicago's citizens.

In a similar way, Chicago's status as a hub city could make it the Midwest capital of green manufacturing and transit, energy effectiveness, and cradle-to-cradle recycling. Following principles derived from nature's laws provides the framework for developing these new systems.

Consider again Waste=Food. When industrial and architectural systems are modeled on the earth's perpetual flows of energy and nutrients, human productivity can be positive and vital. The biodegradable and infinitely recyclable textiles I've mentioned are just the beginning. We are also working with industrial designers to develop materials, products, supply chains and manufacturing processes that replace industry's cradle-to-grave manufacturing model-the one-way trip to the landfill-with cradle-to-cradle systems. In cradle-to-cradle systems, products are conceived with safe, healthy materials, which are managed within closed-loop cycles. The materials go back to soils safely, or they go back to industry. Every material is either a biological nutrient or a technical nutrient. No waste. No pollution. Just two discrete regenerative metabolisms feeding the urban organism. If Chicago's industrial sector re-invents itself using a cradle-to-cradle model, the nation's hub of green manufacturing and resource recovery may well turn out to be on the shores of Lake Michigan.

Using energy effectively will also support the living city. Along with Chicago's strong commitment to developing solar and wind power, the City is also building three libraries and a police station using LEED standards (Leadership in Energy and Environmental Design) and spending more than $100 million to make existing city buildings more energy efficient and providing grants and incentives for others to do the same. The use of renewable energy sources, already stimulating the emergence of green technology in Chicago, could further charge the growth of new industries, such as the manufacture of wind turbines. Indeed, Chicago could jumpstart the entire wind industry and become known as "the city that makes wind turbines for the world." This could supercede traditional coal generated energy and simultaneously begin to power Chicago's transit system. Going to work? Ride the wind. It's not so far fetched; in Calgary the subway is partially powered by prairie winds. Gives a whole new meaning to "Windy City."

With these pieces in place, we can begin to see Chicago's metabolism rendered visible. We can imagine the flow of biological and technical nutrition between city and hinterland in an entirely different landscape of "material connections." The ecologically connected city receives food, water and energy from a very broad nexus of solar-powered, biologically-based, photosynthetic systems. The energy of the sun is harvested on rooftops; rural windmills power city buildings; water falls on hard urban surfaces but also on rooftop gardens and a connected network of green spaces, and it all flows safely into the ground, into the watershed, into the air. In the countryside, farmers grow good food using implements manufactured in the city-technical nutrients-and the city, a visceral, breathing body, receives its nourishment from the hinterlands, digests it and then excretes it back to its source, returning biological nutrients to replenish the rural soil. The windmills on the farm, source of a new cash crop, are forged in the city, produce power for the region in the countryside, and then are returned to the city every 20 years to be refurbished and returned to the farm. Everything moves in regenerative cycles, from city to country, country to city, all the polymers, metals, synthetic fibers and communications software flowing safely in the technical metabolism, all the photosynthetic nutrients flowing in the biological metabolism. The organic and the esthetic bring the city to life.

Creating Community Wealth
This vision comes home in Chicago's neighborhoods. Clean, vital industry; energy effectiveness; safe, affordable housing; and good mobility systems provide the infrastructure and the wherewithal for strong community life. They are the basics that no one should be without.

Why not go beyond the basics? The neighborhood, with the street as its lifeblood, is perhaps where economic, social and environmental concerns mix it up most strongly. For us, that signals opportunity. Areas in urban communities where commerce, patterns of travel, and opportunities for sociability bring people together respond eagerly to attention. They are ripe for "community seeds."

A community seed might be as simple as a laundromat, which can be much more than a place where one's clothes are washed. Imagine, for example, a laundromat on a busy neighborhood street that shares a public courtyard with a daycare center. The laundry is run by a small group of retirees and it serves an older clientele too. The machines are manufactured for disassembly and reuse and are powered cost-effectively by the sun and the wind. The wash water is purified in a botanical garden in the courtyard, where children and their parents mingle with elderly people as they wait for their clothes to dry. The garden's flowering plants brighten what turns out to be a local transit hub. It's not a flashy place, but it's a viable business that provides needed services while bringing the generations together in pleasant surroundings. Places such as these can be important centers of neighborhood life.

Natural areas are important to city neighborhoods too. Developing a plan for a local park can build strong community ties and, once realized, green spaces provide opportunities to relax and reflect among the trees and flowers, a needed respite from active streets. Along with planting trees city-wide, Chicago is supporting the green neighborhood idea with efforts like Greencorps Chicago, a community gardening program. Over the past several years, Greencorps Chicago crews have worked on nearly 500 sites, planting trees, tending flower gardens and receiving on-the-job training in skills such as landscaping and community outreach. Even in small city parks, the experience of getting ones hands in the dirt and planting a living thing provides Greencorps members a meaningful connection to the natural world. At the same time, it helps create places everyone can enjoy and welcomes non-human nature back to Chicago.

On a larger scale, the City's efforts to protect and restore the lakefront, the Chicago River, and the city's bigger parks are also crucial. These are key areas of Chicago's commons. They are the city's lungs, its habitat for other creatures, its vital threads of landscape, the home of the trees and the earth that absorb and filter water while providing pleasure for all.

The commons are also the baseline of the city's health. To preserve and enhance them we must watch how the water flows. Is storm water absorbed where it falls? Is its passage into the river a slow, percolating flow or a headlong rush? Does rainfall erode the soil or restore it? What kinds of toxins does water pick up on its way to the river?

Ideally, the city would release water at the same rate it would be released if the landscape were in its native vegetated state, the water flowing slowly to the river, clean and ready for reuse. The flow of water, the most basic element of life, will be the measure of our progress. When we can say with confidence that the Chicago River runs clean, the city will be well on its way to being the greenest in America.

As we tread that path, our work on The Chicago Principles will be guided and enhanced by our collaboration with the City and Chicago's citizens. It is our hope that we will together create strategies that provide everyone in Chicago with good health care, clean energy, safe water, hugely effective business models, and daily opportunities to engage the natural world. These changes will make the city an ever more safe, delightful and productive place. And before long, Chicago just might find a new place in the national imagination with an inspiring, restorative vision for urban America.