Please read the instructions carefully.  Use the 3-course resources that I attached, and 3 external resources that I attached two of them, and find a 3rd one to use in the paper.  Please cite them using APA style and don’t forget to build a free website and add the research to it.  The link in the project instruction file.

Rubricfor the 2050 Final Project

The 2050 Project Paper Prompt: Choose an urban environmental issue and research it: The issue must be
urban and environmental. Narrow your focus to one issue (e.g. ‘water scarcity in Cairo’ (not ‘global
warming’). How is this urban environmental issue impacting the city and the city’s residents physically,
economically, politically, and socially? Based on our course materials and your own research discuss how
the urban environmental issue can be mitigated (fixed or reduced), what would be the implementation
process, and what is your desired outcome for the city and its residents? Based on your brilliant solution(s)
to an urban environmental issue discuss your implementation process and strategy and explain how your
city will look like and how it will function for all of its residents.

The Academic Standard 1000-1200 words, 12pt font, New Times Roman, double spaced. Use at least 3
resources from this course and 3 resources from outside of the course. Make sure to include a
bibliography/work cited page, using APA or MLA citation style, and with in-text citations. This paper is
where you will bring what you learned in this course by applying a framework to an urban environmental
issue.

Citation Recourse https://owl.purdue.edu/owl/research_and_citation/resources.html
Citation Recourse https://guides.library.pdx.edu/cite

Framework(s):
o Environmental Justice
o Access/The Commons
o Urban Metabolism/Human Flows
o Climate Change
o Sustainability & Resilience
o Agriculture/Food Systems

Introduce the reader to your urban environmental issue. Write a cohesive narrative on how your topic is
an urban environmental issue and how it impacts the city, its residents/communities, and the
environmental health of our planet. The following questions are to help you think through and guide
your project. The answers to most of these questions should be answered, in some form, in your final
paper. Also included in this list are terms and concepts that should be identified, described, and
discussed in your project. These questions and identifiers are not exhaustive, and they do not have to be
answered any particular order.

Things to identify, define, and discuss

• Identify the urban environmental issue you will be discussing and describe why and how it is an
urban environmental issue.

• Identify and explain your framework and how it will help the reader understand the urban
environmental issue you will be discussing.

• Identify the city and country. If you are taking a closer look, also identify the specific
neighborhood.

• Identify the residents and/or communities who are impacted by the urban environmental issue

and explain how and why.

Questions to help you think through and guide your project

• Why and how is this urban environmental issue taking place?

• What are the municipal policies, practices, and processes that created this urban environmental

issue?

• What residents and/or communities are historically impacted by this urban environmental issue?

• Why are these communities vulnerable to this particular urban environmental issue?

• Is this a new urban environmental issue or does it have a historical legacy?

• Is this urban environmental issue unique to this city or is this a worldwide phenomenon?

• What are the possible policies, practices, and processes you suggest for fixing/mitigating this
urban environmental issue by 2050?

• Who can aid in fixing/mitigating this urban environmental issue? Identify possible individuals,
residents/communities, governments (local, county, state, federal), organizations/agencies
(United Nations, World Bank, International Monetary Fund, Green Peace, Sierra Club) who can
help fix the urban environmental issue. Also discuss what actions they must take to organize and
combat this urban environmental issue.

• Is there infrastructure and/or technology that can be created, retrofitted, or used to help fix this
urban environmental issue? If so, name it/them and also address the implementation processes.
If these infrastructures and and/or technologies are used in other areas or cities explain how it
must be adjusted for your city and its residents. Do these fixies bring about new urban
environmental concerns?

• How can residents and communities most impacted by this environmental issue be at the table
in fixing it as well as included in the decision-making process to help alleviate this urban
environmental issue?

• What does a socially and environmental just outcome look like and how does it function for this
city, its residents, and the environment?

The Webpage/Blog

This is your opportunity to bring out your creative side to this project. Use images, links, and other
media help showcase your work. If you refer to any of these materials in your paper make sure you cite
the appropriate sources and in the correct way. Label all images and cite their correct sources within the
webpage and next to the image.

Use a free website builder (Weebly is free and highly suggested) here’s a link…
https://www.websitetooltester.com/en/blog/best-free-website-builders/

Submit your final paper (in a word doc) with your website link by 3/15/2021, by 11:59 pm.
All the weblinks will be made available to you via an announcement

11/16/2020 The Role of Highways in American Poverty – The Atlantic

https://www.theatlantic.com/business/archive/2016/03/role-of-highways-in-american-poverty/474282/ 1/5

Sunday tra�ic from New York City to the Jersey Shore in 1941  (LIBRARY OF CONGRESS )

Editor’s Note: is article is adapted from remarks delivered by the author on March 16 at

the University of Arkansas’s Clinton School of Public Service, in Little Rock.

Little Rock is a fascinating city. With its river and renovated warehouses and bustling

River Market district, it reminds me a little bit of Pittsburgh, where I lived a decade ago

when I was starting my journalism career. At that time, Pittsburgh was still the butt of

many jokes, though determined city planners were starting to drive the transformation

that’s made it so popular. Today, there’s a growing population downtown and tech

companies are locating in the city once known for steel.

It’s a funny thing about cities: ey’re all unique, but they sometimes experience busts

and booms in the same way. Just look at all the cities across the country that are

experiencing a craft-beer renaissance and have condos in renovated warehouses

downtown.

Perhaps that’s why policymakers in the 1940s and 1950s thought of cities as human

bodies, bodies that had sicknesses and required cures. Bodies that got sick from the

same diseases and would improve from the same medicine.

MORE FROM OUR PARTNERS

e postwar years were a time of unprecedented prosperity, when Americans were

buying refrigerators and televisions and homes, and wanted to leave the crowded heart

of city centers for space to put all their new belongings. e rise of the automobile

helped them do this. In 1940, 60 percent of Americans owned cars. In 1960, 80

percent did. Today, 95 percent of Americans own cars.

is increase of people heading to the suburbs in their cars caused something else new:

lots and lots of traffic. And to city planners, this was making communities unhealthy.

By the 1950s, highways were being recommended as “the greatest single element in the

cure of city ills,” according to Joseph DiMento, an Irvine professor who has studied

highway construction during that era. To keep cities healthy, planners said, regions

BUSINESS

e Role of Highways in American
Poverty
ey seemed like such a good idea in the 1950s.

A L A N A S E M U E L S M A R C H 1 8 , 2 0 1 6

What Motivates Companies to Do Good—Altruism, or Guilt?•

e False Promise of Last Year’s Wage Gains•

e Folly of State-Level Tax Cuts•

https://www.theatlantic.com/category/next-economy

http://papers.ssrn.com/sol3/papers.cfm?abstract_id=1392502

https://www.theatlantic.com/business/

https://www.theatlantic.com/author/alana-semuels/

https://www.theatlantic.com/business/archive/2016/03/what-motivates-companies-to-do-good/473511/

https://www.theatlantic.com/business/archive/2016/03/analyzing-2015s-wage-gains/473226/

https://www.theatlantic.com/business/archive/2016/03/state-budget-crisis/473157/

11/16/2020 The Role of Highways in American Poverty – The Atlantic

https://www.theatlantic.com/business/archive/2016/03/role-of-highways-in-american-poverty/474282/ 2/5

needed unclogged arteries for a working circulatory system. In short, cities needed

highways to carry people out of the heart and to the rest of the body.

Luckily for city planners who wanted to keep their cities healthy, there was federal

money available to anyone who wanted to put in modern highways. While the 1944

Federal Highway Act only offered to cover 50 percent of construction costs for

highways, by 1956, the federal government had upped that share to 90 percent. So if

you’re a city planner in the 1950s, you can put in roads from your city to the fast-

growing suburbs for almost no cost at all.

Of course, there were people who couldn’t move to the suburbs. African Americans

were denied home loans by the federal government in certain areas, a practice called

redlining. Restrictive covenants prevented homeowners from selling to certain types of

people, often including African Americans. And they were also denied jobs and other

opportunities that would have allowed them to afford to buy a home in the �rst place.

When I was in Syracuse, I met a man named Manny Breland, who received a

scholarship to play basketball at Syracuse, graduated with a teaching degree, and was

denied job after job because he was black.

In many cities, these restrictions left African Americans crowded into small

neighborhoods. ey essentially weren’t allowed to move anywhere else.

City planners had a solution for this, too. ey saw the crowded African American areas

as unhealthy organs that needed to be removed. To keep cities healthy, planners said,

these areas needed to be cleared and redeveloped, the clogged hearts replaced with

something newer and spiffier. But open-heart surgery on a city is expensive. Highway

construction could be federally funded. Why not use those federal highway dollars to

also tear down blight and rebuild city centers?

e urban planner Robert Moses was one of the �rst to propose the idea of using

highways to “redeem” urban areas. In 1949, the commissioner of the Bureau of Public

Roads, omas MacDonald, even tried to include the idea of highway construction as a

technique for urban renewal in a national housing bill. (He was rebuffed.) But in cities

across America, especially those that didn’t want to—or couldn’t—spend their own

money for so-called urban renewal, the idea began to take hold. ey could have their

highways and they could get rid of their slums. With just one surgery, they could put in

more arteries, and they could remove the city’s heart.

is is exactly what happened in Syracuse, New York. e city had big dreams of

becoming an East Coast hub, since it was close to New York City, Pittsburgh,

Cleveland, and Boston. (In the early days of the car, close was relative.) Use federal

funds to build a series of highways, planners thought, and residents could easily get to

the suburbs and to other cities in the region. After all, who wouldn’t want to live in a

Syracuse that you could easily leave by car? And, if they put the highway in just the

right place, it would allow the city to use federal funds to eradicate what they called a

slum area in the center city.

at neighborhood, called the 15th Ward, was located between Syracuse University and

the city’s downtown. It was predominantly African American. One man who lived there

at the time, Junie Dunham, told me that although the 15th Ward was poor, it was the

type of community that you often picture in 1950s America: fathers going off to jobs in

the morning; kids playing in the streets; families gathering in the park on the weekends

or going on Sunday strolls. He remembers collecting scraps from the streets and

bringing them to the junkyard for pennies, which he would use to buy comics.

To outsiders, though, the 15th Ward was the scene of abject poverty close to two of

Syracuse’s biggest draws—the university and downtown. ey worried about race riots

because so many people were crowded into the neighborhood and prevented from

going anywhere else. ey decided that the best plan would be to tear down the 15th

Ward and replace it with an elevated freeway.   

e completion of the highway, I-81, which ran through the urban center, had the

same effect it has had in almost all cities that put interstates through their hearts. It

decimated a close-knit African American community. And when the displaced residents

from the 15th Ward moved to other city neighborhoods, the white residents �ed. It was

easy to move. ere was a beautiful new highway that helped their escape.

But this dynamic hurt the city’s �nances, too. As suburbs grew, they broke off from

cities, taking with them tax revenues, even though their residents still used city services.

Although the Syracuse region was relatively healthy, the city started to get very sick.

http://www.pbs.org/wnet/need-to-know/environment/the-legacy-of-robert-moses/16018/

https://www.theatlantic.com/business/archive/2015/11/syracuse-slums/416892/

11/16/2020 The Role of Highways in American Poverty – The Atlantic

https://www.theatlantic.com/business/archive/2016/03/role-of-highways-in-american-poverty/474282/ 3/5

Between 1940 and 2000, the population of the city of Syracuse shrank 30 percent, from

about 205,000 to 147,000. e population of Onondaga County, where Syracuse is

located, grew 55 percent, from 295,000 to 458,000.

Even today, the region is continuing to sprawl. e population of Onondaga County

peaked in 1970 and has stayed even since then. But residents are moving farther and

farther out. e county has added 7,000 housing units, 147 subdivisions, and 61 miles

of new roads since 2000. Developers build 160 units a year in areas that were once

rural. at’s costing the county money and resources as it adds sewer systems, water

pipes, and stormwater drainage to far-�ung subdivisions. As the county spends money,

the city is struggling to come up with enough revenue for essential things like mass

transit and schools.

What’s more, as the suburbs grow, they’re continuing to make sure that only wealthy

people can live there. ey pass zoning laws that restrict multifamily units. ey require

minimum lot sizes so that their only residents are people who can afford to live in big

houses. It’s a different kind of discrimination than half a century ago, but

discrimination nonetheless.

Today, the city of Syracuse has the highest concentration of poverty in America. What

that means is that large proportions of its population live below the federal poverty line,

and that they’re surrounded by other poor people, too. Nearly two-thirds of the black

poor live in high-poverty neighborhoods in Syracuse. Around 62 percent of the

Hispanic poor live in high-poverty neighborhoods.

Of course, the highway isn’t the only reason there’s so much concentrated poverty in

Syracuse. e economy has changed, and big employers such as the Carrier

Corporation and other manufacturing companies have left for overseas. Wages in

Syracuse and across America have remained stagnant, so even those people who are

employed are �nding it is much harder to make ends meet than it used to be.

Ironically, the people who are left in Syracuse now live in more concentrated poverty

than the people of the 15th Ward, which city leaders saw as so blighted decades ago.

is is bad for the health of the region. We know that people who live in concentrated

poverty have a much harder time succeeding because they’re surrounded by other poor

people. e economist Raj Chetty made this very clear in a series of papers he’s

published in the last two years through the Equality of Opportunity project. He found

that neighborhoods matter, and that a low-income child who is born in certain low-

income neighborhoods has a much smaller shot of achieving upward mobility than a

low-income child born in a better neighborhood.

Now, there are programs that move poor families from areas of concentrated poverty to

wealthy suburbs. I’ve written about some of them. Children thrive when they’re taken

out of housing projects and moved to condos where there are trees, parks, places to ride

their bikes, and good schools nearby. But it’s not realistic to move every family to a

different neighborhood, and besides, many people don’t want to move.

What does work, though, is bringing cities together so that poverty isn’t so

concentrated, so that the rich can’t just leave or wall themselves off from the poor, so

that the poor aren’t trapped in areas of concentrated poverty—what people used to call

slums.

* * *

In the last decade, Americans’ ideas of where they want to live have been changing.

Young professionals and Baby Boomers are moving back to inner cities, fueled by the

desire to live somewhere walkable, near restaurants, bars, and offices, where they don’t

need to have cars. A freeway passing through the heart of a city does not jibe very well

with an urban renaissance.

After all, walkable cities where people want to live probably don’t also have noisy

highways that create physical and psychological rifts that are extremely difficult to

bridge.

In some cities, planners have decided to help that urban renaissance and tear down the

freeways that seemed like a good idea in the 1950s.

Boston tore down its Central Artery in its famous Big Dig, turning a waterfront area of

the city that had long been clogged with traffic into a popular park and walking area.

Milwaukee demolished the Park East freeway in 1999 and urban development has

blossomed in the neighborhoods created by the highway’s removal. Manpower

http://www.syracuse.com/news/index.ssf/2015/09/syracuse_has_nations_highest_poverty_concentrated_among_blacks_hispanics.html

http://equality-of-opportunity.org/images/mobility_geo

http://www.nielsen.com/us/en/insights/news/2014/millennials-prefer-cities-to-suburbs-subways-to-driveways.html

https://www.theatlantic.com/business/archive/2015/11/highways-destroyed-americas-cities/417789/

11/16/2020 The Role of Highways in American Poverty – The Atlantic

https://www.theatlantic.com/business/archive/2016/03/role-of-highways-in-american-poverty/474282/ 4/5

Corporation moved its headquarters to the area, and the average assessed land value

there grew 45 percent. e economically depressed town of New Haven is in the midst

of a project called Downtown Crossing, which has removed parts of Route 34 and is

creating a business district in an area of town bisected by the freeways.

Even some people in Syracuse want to tear down I-81. Like many highways built by

idealistic planners in the 1950s, I-81 is reaching the end of its useful life, according to

engineers. It isn’t wide enough to meet current highway standards, and parts of it are

literally falling apart. Some urban planners want to tear it down to create an urban

boulevard. For more than half a century, the road has divided the city, they say, and it’s

time to knit it together back again.

Some cities are taking the opposite approach. Alabama’s highway department is seeking

to widen parts of a highway that bisect Birmingham, Alabama, though the proposal

faces opposition from business leaders. Florida’s highway department declined to tear

down a highway in Miami called the Overton Expressway.

In the 1950s, when so many highways were built, planners across the country wanted to

help citizens access the prosperity that seemed accessible to everyone in the postwar

years. But starting with the exodus to the suburbs around that time, and continuing to

this day, prosperity has been out of reach for many Americans.

If part of a body is sick, the whole body can’t be healthy, and many cities across America

have parts that aren’t doing very well. But there are regions that are trying to become

healthier by coming together, rather than pulling apart. Tearing down a highway can be

one way to do this. But it’s not the only way. My colleague Derek ompson has

written about the miracle of Minneapolis, where high-income communities share tax

revenues and real estate with lower-income communities to spread prosperity. A year

ago, I visited Louisville, where a court ordered the county and city to combine their

school districts in order to integrate their schools. Today, Louisville is still trying to keep

its county and city schools integrated, even after the Supreme Court told the city it no

longer had to do so. In Chicago, a regional housing authority that covers eight counties,

including Cook County, is working to move families from the inner city to higher-

opportunity neighborhoods. Some cities use inclusive zoning, in which all new

construction must include a certain percentage of housing for low-income residents,

which means that the wealthy can’t separate themselves from the poor.

ese cities have tried to tear down barriers that prevent all of their residents from

reaching their full opportunity. Sometimes those barriers are highways. Sometimes

they’re something else entirely. Tearing down a highway isn’t the only way to make a

city healthy again. But building a new one—or expanding an existing one—seems a

sure�re way to make a city sick.

We want to hear what you think about this article. Submit a letter to the editor or write to

letters@theatlantic.com.

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lable at ScienceDirect

Environmental Pollution 159 (2011) 1965e1973

Contents lists avai

Environmental Pollution

journal homepage: www.elsevier.com/locate/envpol

Review

The study of urban metabolism and its applications to urban planning and design

C. Kennedy a,*, S. Pincetl b, P. Bunje b

a Department of Civil Engineering, University of Toronto, Toronto, Canada
b Institute of the Environment, UCLA, CA, United States

a r t i c l e i n f o

Article history:
Received 12 October 2010
Accepted 15 October 2010

Keywords:
Cities
Energy
Materials
Waste
Urban planning
Urban design
Greenhouse gas emissions
Sustainability indicators

* Corresponding author.
E-mail address: christopher.kennedy@utoronto.ca

0269-7491/$ e see front matter � 2010 Elsevier Ltd.
doi:10.1016/j.envpol.2010.10.022

a b s t r a c t

Following formative work in the 1970s, disappearance in the 1980s, and reemergence in the 1990s,
a chronological review shows that the past decade has witnessed increasing interest in the study of
urban metabolism. The review finds that there are two related, non-conflicting, schools of urban
metabolism: one following Odum describes metabolism in terms of energy equivalents; while the second
more broadly expresses a city’s flows of water, materials and nutrients in terms of mass fluxes. Four
example applications of urban metabolism studies are discussed: urban sustainability indicators; inputs
to urban greenhouse gas emissions calculation; mathematical models of urban metabolism for policy
analysis; and as a basis for sustainable urban design. Future directions include fuller integration of social,
health and economic indicators into the urban metabolism framework, while tackling the great
sustainability challenge of reconstructing cities.

� 2010 Elsevier Ltd.

All rights reserved.

1. Introduction

The concept of the urban metabolism, conceived by Wolman
(1965), is fundamental to developing sustainable cities and
communities. Urban metabolism may be defined as “the sum total of
the technical and socio-economic processes that occur in cities,
resulting in growth, production of energy, and elimination of waste”
(Kennedy et al., 2007). In practice, the study of an urban metabo-
lism involves ‘big picture’ quantification of the inputs, outputs and
storage of energy, water, nutrients, materials and wastes for an
urban region. While research on urban metabolism has waxed and
waned over the past 45 years, in the last decade it has accelerated.
Moreover, as this review will show, practical applications of urban
metabolism are emerging.

The notion of urban metabolism is loosely based on an analogy
with the metabolism of organisms, although in other respects
parallels can also be made between cities and ecosystems. Cities are
similar to organisms in that they consume resources from their
surroundings and excrete wastes. “Cities transform raw materials,
fuel, and water into the built environment, human biomass and waste”
(Decker et al., 2000). Of course, cities are more complex than single
organisms e and are themselves home to multitude of organisms e
humans, animals and vegetation. Thus, the notion that cities are

(C. Kennedy).

All rights reserved.

like ecosystems is also appropriate. Indeed, the model of a natural
ecosystem is in some respects the objective for developing
sustainable cities. Natural ecosystems are generally energy self-
sufficient, or are subsidized by sustainable inputs, and often
approximately conserve mass, through recycling by detrivores.
Were cities to have such traits, they would be far more sustainable.
Contemporary cities, however, have large linear metabolism with
high through flows of energy and materials.

The first purpose of this paper is to review the development of
the urban metabolism concept largely through academic research
literature. The chronological review shows that after a few forma-
tive studies in the 1970s, interest in urban metabolism almost
disappeared in the 1980s. Then after slowly reemerging in the
1990s, study of urban metabolism has grown in the past 10 years,
with over 30 papers produced. The review also describes how two
related, non-conflicting, schools of study have developed. One,
primarily based on the work of Odum, aims to describe urban
metabolism in terms of energy equivalents. The other takes
a broader approach, expressing a city’s flows of water, materials
and nutrients in terms of mass fluxes.

The second purpose of this paper is to ask: What use are urban
metabolism studies for urban planning and design? Most studies of
urban metabolism have primarily been accounting exercises. These
are useful in that they provide indicators of urban sustainability,
and the measures of energy consumption, material flows and
wastes from the urban metabolism are also necessary to quantify
greenhouse gas emissions for cities. Beyond accounting exercises,

mailto:christopher.kennedy@utoronto.ca

www.sciencedirect.com/science/journal/02697491

http://www.elsevier.com/locate/envpol

http://dx.doi.org/10.1016/j.envpol.2010.10.022

http://dx.doi.org/10.1016/j.envpol.2010.10.022

http://dx.doi.org/10.1016/j.envpol.2010.10.022

C. Kennedy et al. / Environmental Pollution 159 (2011) 1965e19731966

moreover, the review of applications shows how study of urban
metabolism is also being used as a basis for sustainable urban
design, and how a few mathematical models of urban metabolism
have been used for policy analysis.

2. Development of the urban metabolism concept

Since the first study of an urban metabolism by Wolman in 1965,
about 15e20 comprehensive studies of urban metabolism have
been undertaken, in addition to numerous related studies (Table 1).
This section describes the evolution of methodological approaches
for studying urban metabolism. The primary focus is on quantita-
tive studies, as opposed to works that invoke urban metabolism in

Table 1
Chronological review of urban metabolism studies.

Author (year) City or region of study

Wolman (1965) Hypothetical US city of
1 million people

Zucchetto (1975) Miami
Stanhill (1977); Odum (1983) 1850s Paris
Hanya and Ambe (1976). Toyko
Duvigneaud and

Denayeyer-De Smet (1977)
Brussels

Newcombe et al. (1978);
Boyden et al. (1981)

Hong Kong

Girardet (1992)
Bohle (1994)

European Environment
Agency (1995)

Prague (comprehensive
metabolism study)

Nilson (1995) Gävle, Sweden
Baccini (1997). Swiss Lowlands
Huang (1998). Taipei
Newman (1999);

Newman et al. (1996)
Sydney

Stimson et al. (1999) Brisbane & Southeast Queensla
Hermanowicz and Asano (1999)
Hendriks et al. (2000). Vienna & Swiss Lowlands
Warren-Rhodes and Koenig (2001). Hong Kong
Baker et al. (2001) Phoenix & Central Arizona
Sörme et al. (2001) Stockholm
Svidén and Jonsson (2001) Stockholm
Obernosterer and Brunner (2001) Vienna
Færge et al. (2001) Bangkok
Chartered Institute of

Wastes Management (2002)
London

Gasson (2002) Cape Town
Barrett et al. (2002) York, UK
Obernosterer (2002)
Sahely et al. (2003). Toronto
Emmenegger et al. (2003) Geneva
Burstrom et al. (2003) Stockholm
Gandy (2004)
Lennox and Turner (2004)
Hammer and Giljum (2006) Hamburg, Vienna and Leipzig
Kennedy et al. (2007)
Schulz (2007) Singapore
Barles (2007a) Paris
Forkes (2007) Toronto
Zhang and Yang (2007) Shenzhen, China
Ngo and Pataki (2008) Los Angeles
Chrysoulakis (2008)
Schremmer and Stead (2009)
Barles (2009, 2007b) Paris
Zhang et al. (2009) Beijing
Niza et al. (2009) Lisbon
Deilmann (2009)
Baker et al. (2001)
Thériault and Laroche (2009) Greater Moncton,

New Brunswick
Browne et al. (2009) Limerick, Ireland

a political science context (e.g., Heynen et al., 2005), or in a quali-
tative historical context (e.g., Tarr, 2002).

In his seminal study, Wolman (1965) used national data on
water, food and fuel use, along with production rates of sewage,
waste and air pollutants to determine per capita inflow and outflow
rates for a hypothetical American city of one million people (White,
2002). His approach to determining material flows, even with the
omission of important inputs such as electricity, infrastructure
materials, and other durable goods, helped focus attention on
system-wide impacts of the consumption of goods and the gener-
ation of wastes within the urban environment (Decker et al., 2000).

The first metabolism studies of real cities were conducted in the
1970s. Interestingly the first three studies of Tokyo (Hanya and
Ambe, 1976), Brussels (Duvigneaud and Denayeyer-De Smet,

Notes/contribution

Seminal study

Emergy approach
Emergy approach

Includes natural energy balance

Particularly comprehensive metabolism study

Recognized link to sustainable development of cities
Critiqued metabolism perspective for studying food in
developing cities
Energy use data for Barcelona and seven other European
cities given in the report.
Phosphorus budget

Emergy approach
Adds liveability measures

nd Framework relating urban metabolism to quality of life.
Water

Nitrogen balance
Heavy metals
Mercury
Lead
Nitrogen & Phosphorus

Materials
Metals

Nitrogen & Phosphorus
Water
State of the Environment report
Materials
Review of changing metabolism
Materials
Historical study of nitrogen in food metabolism
Nitrogen in food metabolism
Develops eco-efficiency measure

New project under EU 7th framework
New project under EU 7th framework
Analysis of central city, suburbs and region.
Emergy approach
Materials
Studies relationship between metabolism and city surface
Water
Water

Develops measure of metabolic efficiency

C. Kennedy et al. / Environmental Pollution 159 (2011) 1965e1973 1967

1977) and Hong Kong (Newcombe et al., 1978) were conducted by
chemical engineers, ecologists and civil engineers respectively,
recognizing the interdisciplinary nature of the topic. Given Hong
Kong’s status as a quasi-independent city state, the study by
Newcombe et al. was particularly rich, including description of
material inputs that were difficult to establish in later studies. The
Hong Kong study was conducted under a UNESCO Man and the
Biosphere project, which also included work on Barcelona and
Rome (Barles, 2010; data on energy flows through Barcelona from
Pares et al. (1985), are given by the European Environment Agency,
1995). The Brussels metabolism study was also unique in that it
went beyond quantification of anthropogenic energy inputs to
include a natural energy balance (Fig. 1).

Also during the 1970s, systems ecologists primarily under the
leadership of Odum were studying urban metabolism from
a slightly different perspective. The Odum school was primarily
concerned with describing metabolism in terms of solar energy
equivalents (or emergy with an ‘m’). Using Odum’s systems nota-
tion, Zucchetto (1975) produced a study of Miami’s urban metab-
olism. Odum (1983) applied his approach to data presented by
Stanhill (1977) for 1850s Paris, producing in a sense the oldest
study of an urban metabolism. Although Odum’s approach to
studying urban metabolism has not become mainstream, it
continues today through the work of Huang, primarily for Taipei
(Huang, 1998; Huang and Hsu, 2003) and Zhang et al. (2009) for
Beijing.

During the 1980s and early 1990s, progress in the study of urban
metabolism was modest. There was an international symposium on
urban metabolism held in Kobe, Japan, September 6e11, 1993, but
few of the papers were published. One exception was the paper by
Bohle (1994) which considered the potential to use an urban
metabolism perspective to examine urban food systems in

Fig. 1. The urban metabolism of Brussels, Belgium in the ea

developing countries, and was critical of its application. Writers
such as Girardet (1992), however, began to see the key connection
between urban metabolism and the sustainable development of
cities.

During the 1990s, there was progress in the development of the
method of material flow analysis (MFA), which included application
to cities. Baccini and Brunner’s (1991) Metabolism of the Anthropo-
sphere was followed by a substantial textbook Regionaler Stoff-
haushalt on regional material flow analysis by Baccini and Bader
(1996). Differing from Odum’s focus on energy, MFA reports
stocks and flows of resources in terms of mass. As an example, in
the EUROSTAT guidelines for MFA, quantities of fossil fuels are
reported in units of kilotonnes or kilotonnes per year. The work of
Baccini and Brunner, however, building upon the earlier metabo-
lism studies of the 1970s, more usually reports energy flow in terms
of joules, with a city’s flows of water, material and nutrients
expressed as mass fluxes. This is arguably the approach of the
mainstream school of urban metabolism.

From a deep sustainability perspective there is some merit to
Odum’s emergy approach, but the mainstream school of urban
metabolism uses more practical units. The approach of Odum and
co-workers is an attempt to apply a biophysical value theory that is
applicable to both ecological and economic systems (Huang, 1998).
It recognizes that there is variation in the quality of different forms
of energy, i.e., different forms of energy (fuels, electricity, solar)
accomplish different amounts of work. Hence solar energy equiv-
alents are used as a universal metric. The mainstream school of
urban metabolism, however, essentially just uses the units that
local government officers would use, recognize and understand,
e.g., in water works departments, solid waste management, or
utilities, etc. Nevertheless, the two schools are not that far apart;
they quantify the same items, but just use different units.

rly 1970s (Duvigneaud and Denayeyer-De Smet, 1977).

C. Kennedy et al. / Environmental Pollution 159 (2011) 1965e19731968

The turn of the millennium saw rejuvenation in studies of urban
metabolism: Newman (1999) published a study of the metabolism
of Sydney; Baccini, Brunner and co-workers provided applications
of MFA to Vienna and part of the Swiss Lowlands (Hendriks et al.,
2000; Baccini, 1997); and Warren-Rhodes and Koenig (2001)
produced an update of the metabolism of Hong Kong. This latter
study was particularly powerful in demonstrating the need to
understand urban metabolism. It described the increasing envi-
ronmental impacts that of Hong Kong’s transition from
a manufacturing centre to a service-based economy with the addi-
tion of more than 3 million people between 1971 and 1997. Per
capita food, water and materials consumption increased by 20%, 40%
and 149%, respectively over 1971 values. Moreover, total air emis-
sions, carbon dioxide outputs, municipal solid wastes and sewage
discharges rose by 30%, 250%, 245% and 153% respectively (Warren-
Rhodes and Koenig, 2001). These increases in the per capita
metabolism of Hong Kong may be linked to higher consumption
related the city’s substantially increased wealth, although the
authors do not fully explore the reasons behind the changes.

Newman’s work on the metabolism of Sydney was conducted as
part of a State of the Environment (SOE) report for Australia
(Newman, 1999; Newman et al., 1996). Of particular note, was
Newman’s inclusion of liveability measures. He proposed an
extended metabolism model, which included indicators of health,
employment, income, education, housing, leisure and community
activities. Connections between urban metabolism and quality of
life have subsequently been made by other Australian researchers
(Stimson et al., 1999; Lennox and Turner, 2004).

Kennedy et al. (2007) conducted a review of urban metabolism
studies with a focus on understanding how metabolism was
changing. Incorporating analyses of Greater Toronto (Sahely et al.,
2003), Cape Town (Gasson, 2002), and Greater London (Chartered
Institute of Wastes Management, 2002) with earlier studies, the
review showed that the metabolism of cities is generally increasing.
Kennedy et al. also highlighted the importance of understanding
changes in stocks within the urban metabolism. Accumulation
processes such as water in urban aquifers, construction materials,
heat stored in rooftops and pavements, and nutrients deposited in
soils or waste sites, need to be appropriately managed.

Studies of nutrients in the urban metabolism are amongst nar-
rower studies focused on individual substances. Two key nutrients:
nitrogen and phosphorus, were studied for Bangkok (Færge et al.,
2001) and Stockholm (Burstrom et al., 2003), as well as in the
Hong Kong metabolism studies. Nitrogen fluxes in food metabolism
have been studied for Toronto (Forkes, 2007) and historically for
Paris (Barles, 2007a). A full nitrogen balance was also conducted for
the Central Arizona-Phoenix (CAP) ecosystem (Baker et al., 2001),
and a phosphorus budget for the Swedish municipality of Gävle
(Nilson, 1995). These studies have generally found that nutrients
are accumulating in cities.

Further work has invoked the urban metabolismwhen addressing
urban water issues. For example, see: Hermanowicz and Asano
(1999), Gandy (2004), Thériault and Larcohe (2009), Sahely and
Kennedy (2007) and Baker (2009).

Other studies have focused primarilyonurban material stocks and
flows. These include studies of Lisbon (Niza et al., 2009), Singapore
(Schulz, 2007) and York, UK (Barrettet al., 2002). Hammer and Giljum
(2006) quantified material flows for Hamburg, Vienna and Leipzig.
Some researchers have studied specific metals in the urban metab-
olism, recognizing them to be both environmental burdens, but also
potentially future resources (Sörme et al., 2001; Svidén and Jonsson,
2001; Obernosterer and Brunner, 2001; Obernosterer, 2002). Further
material flow studies for Shenzhen, China (Zhang and Yang, 2007)
and Limerick, Ireland (Browne et al., 2009) are notable for the
development of measures of efficiency of the urban metabolism.

As Table 1 reveals, there has been an increasing amount of
research on urban metabolism in recent years. In addition to the
studies in the paragraphs above, quantification of urban metabo-
lism has been conducted for Los Angeles (Ngo and Pataki, 2008),
Geneva (Emmenegger et al., 2003) and Paris (Barles, 2007b, 2009).
Broader work has linked urban metabolism to: ecosystem appro-
priation by cities (Folke et al., 1997); the accumulation of toxic
materials in the urban building stock (Brunner and Rechberger,
2001); historical growth in the transportation of materials
(Fischer-Kowalski et al., 2004); economies of scale for urban
infrastructure systems (Bettencourt et al., 2007); and differences in
greenhouse gas emissions from global cities (Kennedy et al.,
2009a). There is rich variety in the scope of research: Deilmann
(2009) studies spatial attributes of urban metabolism; Kaye et al.
(2006) review urban biogeochemical cycles in the urban metabo-
lism; and Fung and Kennedy (2005) develop links with urban
macroconomic models. Further research papers may be expected
from two projects on urban metabolism recently funded under the
EU 7th framework: SUME (Schremmer and Stead, 2009) and
BRIDGE (Chrysoulakis, 2008).

3. Applications

From its conception by Wolman, urban metabolism was studied
for practical reasons; Wolman was particularly concerned with air
pollution and other wastes produced in US cities. So beyond the
study of urban metabolism to understand it, in a scientific sense,
there are practical applications. Here we review applications in
sustainability reporting, urban greenhouse gas accounting, math-
ematical modelling for policy analysis, and urban design. This list of
four is perhaps not exhaustive; urban metabolism studies are data
rich and may have other potential applications. These four serve as
examples that demonstrate practical applications of urban
metabolism for urban planners and designers.

3.1. Sustainability indicators

Study of the urban metabolism is an integral part of State of the
Environment (SOE) reporting and provides measures that are
indicative of a city’s sustainability. The urban metabolism includes
pertinent information about energy efficiency, material cycling,
waste management, and infrastructure in urban systems. The
parameters of the urban metabolism generally meet the criteria for
good sustainability indicators as outlined by Maclaren (1996); they
are: scientifically valid (based on principles of conservation of
energy and mass), representative, responsive, relevant to urban
planners and dwellers, based on data that is comparable over time,
understandable and unambiguous. The main objectives of SOE
reporting are to analyze and describe environmental conditions
and trends of significance and to serve as a precursor to the policy-
making process (Maclaren, 1996).

3.2. Inputs to urban greenhouse gas accounting

With many cities and communities aiming to reduce their
greenhouse gas (GHG) emissions, a particularly useful application
of urban metabolism metrics is their role in quantifying urban GHG
emissions. The actual emissions of carbon dioxide, methane and
other GHGs that are directly emitted from a city are legitimate
components of the urban metabolism in themselves. The GHG
emissions that are attributed to a city are, however, usually broader
in scope including some emissions that are produced outside of
urban boundaries, e.g., from electricity generation or disposal
of exported waste. Whether the GHG emission occurs inside or
outside of city boundaries, its calculation requires measures of

Table 2
Components of urban metabolism that are required for the inventorying of GHG emissions for cities and local communities.

Components of urban metabolism Preferred units

Total electricity consumption GWh
Consumption of heating and industrial fuels by each fuel type

(e.g., natural gas, fuel oils, coal, LPG e includes fuels used in combined heat and power plants).
TJ for each fuel type

Total consumption of ground transportation fuels (gasoline, diesel, other) based on sales data. Million litres for each fuel type
Volume of jet fuel loaded onto planes at airports within the boundary of the city/urban region. Million litres
Volume of marine fuel loaded onto vessels at the city’s port (if applicable). Million litres
Tonnage and composition of landfill waste (% food, garden, paper, wood, textiles,

industrial, other/inert) from all sectors; and percentage of landfill methane that is captured
t and %

Tonnage of solid waste incinerated (if applicable) t
Masses of steel, cement, and other materials or chemicals produced in the city causing

non-energy related industrial process emissions.
t

C. Kennedy et al. / Environmental Pollution 159 (2011) 1965e1973 1969

energy consumption, material flows and wastes from the urban
metabolism.

According to the IPCC guidelines, GHG emissions for many
sectors are broadly calculated by multiplication of an activity level
by an emissions factor. For example, GHG emissions for a commu-
nities electricity supply are calculated by multiplying the level of

Table 3
GHG emissions for cities and metropolitan regions (adapted from Kennedy et al., 2009b;

City or metropolitan region Definition

Athens Metropolitan region
Barcelona City
Bologna Province
Brussels Capital region
Frankfurt Frankfurt/Rhein Main
Geneva Canton
Glasgow Glasgow and the Clyde Valley
Hamburg Metropolitan region
Helsinki Capital region
London Greater London
Ljubljana Osrednjeslovenska region
Madrid Comunidad de Madrid
Naples Province
Oslo Metropolitan region
Paris Ile de France
Porto Metropolitan region
Prague Greater Prague
Rotterdam City
Stockholm Metropolitan region
Stuttgart Metropolitan region
Torino Metropolitan region
Veneto Province

Austin City
Calgary City
Denver City and county
Los Angeles County
Minneapolis City
New York City
Portland City
Seattle City
Toronto Greater Toronto Area
Washington District of Columbia

Mexico City City
Rio de Janeiro City
Sao Paulo City

Bangkok City
Beijing Beijing Government administered area
Delhi Metropolitan area
Kolkata National capital territory
Shanghai Shanghai Government administered area
Seoul Seoul City
Tianjin Tianjin Government administered area
Tokyo Tokyo metropolitan government admin. area

Cape Town City

a Excludes aviation and marine emissions.

consumption by the GHG intensity of the regional/state/provincial
or national electricity supply. Emissions factors for fuels used in
heating, transportation or industrial combustion are well estab-
lished from national GHG inventory reporting; they are based on
the combustion properties of the fuel. While the calculations are
more complex for some sectors (e.g., waste), for urban GHG

note see Table 2 in source for differences in methodology).

Year Population Total emissions
million t CO2 e

Per capita
emissions t CO2 e

2005 3,989,000 41.57 10.4
2006 1,605,602 6.74 4.2
2005 899,996 9.97 11.1
2005 1,006,749 7.55 7.5
2005 3,778,124 51.61 13.7
2005 432,058 3.35 7.8
2004 1,747,040 15.30 8.8
2005 4,259,670 41.52 9.7
2005 988,526 6.94 7.0
2003 7,364,100 70.84 9.6
2005 500,021 4.77 9.5
2005 5,964,143 40.98 6.9
2005 3,086,622 12.49 4.0
2005 1,039,536 3.63 3.5
2005 11,532,398 59.64 5.2
2005 1,666,821 12.14 7.3
2005 1,181,610 11.03 9.3
2005 592,552 17.64 29.8
2005 1,889,945 6.88 3.6
2005 2,667,766 42.57 16.0
2005 2,243,000 21.86 9.7
2005 4,738,313 47.29 10.0

2005 672,011 10.48a 15.6a

2003 922,315 16.37a 17.7a

2005 579,744 11.08 19.4
2000 9,519,338 124.04 13.0
2005 387,711 7.03a 18.3a

2005 8,170,000 85.87 10.5
2005 682,835 8.47a 12.4a

2005 575,732 7.82a 13.7a

2005 5,555,912 64.22 11.6
2000 571,723 11.04a 19.3a

2000 8,669,594 35.27a 4.1a

1998 5,633,407 12.11 2.1
2000 10,434,252 14.22 1.4

2005 5,658,953 60.44 10.7
2006 15,810,000 159.00 10.1
2000 15,700,000 20.65a 1.6a

2000 13,200,000 17.80a 1.1a

2006 18,150,000 211.98 11.7
1998 10,321,496 42.03a 4.1a

2006 10,750,000 119.25 11.1
2006 12,677,921 62.02 4.9

2006 3,497,097 40.43 11.6

Fig. 2. Representation of a sustainable metabolism for the Toronto Port Lands,
designed by graduate students at the University of Toronto.

C. Kennedy et al. / Environmental Pollution 159 (2011) 1965e19731970

inventories, the urban metabolism parameters essentially provide
the required measures of activity levels (Table 2).

A comparison of the GHG emissions from ten global cities was
undertaken by Kennedy et al. (2009a, 2010), largely drawing upon
urban metabolism studies. Results from a wider study of GHG
emissions from forty cities are shown in Table 3 (Kennedy et al.,
2009b).

3.3. Dynamic mathematical models for policy analysis

While most researchers have primarily used the urban metab-
olism as the basis of an accounting framework, others have begun
to develop mathematical models of processes within the urban
metabolism. Such mathematical models have mainly been devel-
oped by the MFA community, usually to study specific substances e
metals or nutrients in the urban or regional metabolism. Example
model platforms include SIMBOX (Baccini and Bader, 1996) and
STAN (Cencic and Rechberger, 2008; Brunner and Rechberger,
2004). These models include representation of sub-processes,
stocks and flows within the metabolism, sometimes linked to
economic inputeoutput models.

While the models are useful for determining present material
stock and flows, they can also be used to simulate future changes to
the urban metabolism as a result of technological interventions or
policies. The models are particularly useful for identifying solutions
to environmental issues beyond “end of pipe” approaches.

3.4. Design tools

The potential to use the concept of urban metabolism in an
urban design context is a relatively new development. Perhaps the
first serious attempt to move beyond analysis to design is described
in Netzstadt by Oswald and Baccini (2003). Fernandez and students
in MIT’s School of Architecture have used the perspective of urban
metabolism in considering redesign of New Orleans, while students
in Civil Engineering at the University of Toronto study the urban
metabolism in order to design infrastructure for sustainable cities.

In Netzstadt, Oswald and Baccini begin to demonstrate how
a combination of morphological and physiological tools can be used
in the “long process of reconstructing the city.” Their starting point is
recognition that the centereperiphery model of cities is outdated,
but the new urbanity is not sustainable. They proceed to provide
four principles for redesigning cities: shapability; sustainability;
reconstruction; and responsibility. Five criteria of urban quality:
identification; diversity; flexibility; degree of self-sufficiency; and
resource efficiency, are then sought in a design approach that
includes analysis of urban metabolism. The four major urban
activities: to nourish and recover; to clean; to reside and work; and
to transport and communicate, as identified by Baccini and Brunner
(1991) are assessed in terms of four major components of urban
metabolism: water, food (biomass), construction materials, and
energy. Several examples partially demonstrate the integration of
morphological and physiological perspectives.

Urban metabolism has also been invoked in the much more
rapid reconstruction of New Orleans that followed after Hurricane
Katrina. John Fernandez and students at MIT, use material flow
analysis to help with producing more ecologically sensitive designs
for the city (Quinn, 2007).

Civil Engineering students at the University of Toronto also use
the urban metabolism as a tool to guide sustainable design (Fig. 2).
The students are faced with design challenges typically at the
neighborhood scale, which involve integration of various infra-
structure using the concept of neighborhood metabolism (Codoban
and Kennedy, 2008; Engel Yan et al., 2005; Kennedy, 2007). The
students use best practices in green building design, sustainable

transportation and alternative energy systems in their work. By
tracing the flows of water, energy, nutrients and materials through
an urban system, it can be designed to close loops, thus reducing
the input of resources and output of wastes.

The urban metabolism analysis of one group shows just how
close it came to a fundamentally sustainable design (Fig. 3). Grey-
water was used for toilets, and outdoor use; sludge from waste
water was used on community gardens for food production. Energy
from the imported municipal waste not only powered the build-
ings, it also provided for the light rail system and returned some
excess electricity to the grid. Moreover, fly-ash from the waste
gasification plant was recycled as building material. By partially
closing these loops, inputs of energy, water, materials, and nutri-
ents were significantly reduced.

The tracking of energy and material flows in urban design in
order to reduce environmental impacts is also conducted by prac-
titioners. Arup’s Integrated Resource Modelling (IRM) tool which
was used for master planning of Dongtan and the Thames Gateway
is essentially an urban metabolism model. It is used to assess the
sustainability performance of different strategies for the built
environment.

4. Future directions

There is a growing body of knowledge on urban metabolism.
Over 50 papers have been referenced here, some of which are
relatively comprehensive studies of metabolism, others that
analyze particular components, such as energy, water, nutrients,
metals etc. These studies provide valuable insights into the func-
tioning of specific cities at particular points in time, but there is still
more to learn. There are only few cross-sectional studies of multiple
cities and a lack of time series studies of urban metabolism.

As Barles (2010) observes much of the research on urban
metabolism is now being conducted within the industrial ecology
community, which has broadened from its initial focus on indus-
trial metabolism to include social and urban metabolism. A work-
shop held by industrial ecologists at MIT in January 2010, identified
several research needs, including:

� work on the relationship between urban metabolism and the
urban poor

� efforts to collect and combine energy use data from world cities

Fig. 3. The urban metabolism of the Toronto Port Lands shows reduction in inputs of energy, water, materials, and nutrients due to the partial closing of these loops (designed by
a second group of graduate students at the University of Toronto).

C. Kennedy et al. / Environmental Pollution 159 (2011) 1965e1973 1971

� development of a standard classification system for stocks and
flows in the urban metabolism.

Another important future direction is fuller integration of social,
health and economic indicators into the urban metabolism frame-
work. While others, such as Newman (1999), have previously
proposed that social indicators be included in the urban metabo-
lism, such indicators have tended to be added on. Social, heath and
economic impacts are, however, inherently related to the urban
metabolism. For example, high consumption of gasoline and high
rates of obesity are both related to an auto dependent lifestyle.
Hence, a framework for sustainable city/community indicators,
developed for the Public Interest Energy Research Program (PIER) of
the California Energy Commission, links social, health and economic
indicators to the urban metabolism in the form of a matrix.

The advantages of using an urban metabolism framework as
a unifying research theme are that it (Pincetl and Bunje, 2009):

1. explicitly identifies of the system’s boundaries;
2. accounts for inputs and outputs to the system;
3. allows for a hierarchical approach to research;
4. includes decomposable elements for targeted, sectoral

research;
5. necessitates analysis of policy and technology outcomes with

respect to sustainability goals;
6. isan adaptiveapproach to solutionsandtheirconsequences; and
7. integrates social science and biophysical science/technology.

While there is much interest in the science of urban metabo-
lism, great efforts are still required to get it established in the

practice of urban planning and design. The need to do so has been
clearly articulated. For example, in contemplating what is required
to approach sustainability, Oswald and Baccini (2003) suggest that
it will require no less than the reconstruction of our cities. They
write:

“Reconstruction . means launching an intelligent experiment in
a democratic society in order to ensure the survival of the
contemporary city. We cannot foresee the final state of this process.
We are defining the quality goals of a new regionally customized
urban life”
“Customization means that every society consisting of several
million people must, for instance, develop concrete ideas on
where they will obtain water, food, material and energy over the
long term, without depleting regional or global resources; ideas
on how they will renew experiential knowledge, promote crea-
tive capabilities and create symbols, without poisoning their
relationship to their own origins or disrupting global
communication”

Significant progress has been made over the past decade by the
green/sustainable building industry in tracking energy and material
flows at the building scale. There is arguably a need for the planning
and design community e specifically architects, engineers and
planners e to step up to higher level. Studies of resource flows for
neighborhood developments or entire cities needs to become
mainstream practice, rather than just a rare exercise for experi-
mental Dongtan-like developments. This requires the design
community to become much more numerate in energy and mate-
rial flows. The challenge ahead is to design the urban metabolism of
sustainable cities.

C. Kennedy et al. / Environmental Pollution 159 (2011) 1965e19731972

Acknowledgment

The authors are grateful for the support of the California Energy
Commission, PIER Program.

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• The study of urban metabolism and its applications to urban planning and design

1 Introduction
2 Development of the urban metabolism concept
3 Applications
3.1 Sustainability indicators
3.2 Inputs to urban greenhouse gas accounting
3.3 Dynamic mathematical models for policy analysis
3.4 Design tools
4 Future directions
Acknowledgment
References

Urban Planning (ISSN: 2183–7635)
2019, Volume 4, Issue 1, Pages 106–112

DOI: 10.17645/up.v4i1.1988

Editorial

City of Flows: The Need for Design-Led Research to Urban Metabolism

Rob Roggema 1,2

1 Office for Adaptive Planning and Design, Cittaideale, 6707 LC Wageningen, The Netherlands; E-Mail: rob@cittaideale.eu
2 Knowledge Centre NoorderRuimte, Hanze University Groningen, 9747 AS Groningen, The Netherlands

Submitted: 22 January 2019 | Published: 21 February 2019

Abstract
The design of cities has long ignored the flows that shape the city. Water has been the most visible one, but energy and
materials were invisible and/or taken for granted. A little over 50 years ago, Abel Wolman was the first to illuminate the
role of water flows in the urban fabric. It has long been a search for quantitative data while the flows were mostly seen as
separated entities. The fact they invisibly formed the way the city appears has been neglected for many years. In this the-
matic issue the “city of flows” is seen as a design task. It aims to bring to the fore the role flows can play to be consciously
used to make spatial decisions in how and where certain uses and infrastructure is located. Efficient and sustainable.

Keywords
energy; food; food-energy-water nexus; nexus thinking; urban flows; urban metabolism; urban planning; water

Issue
This editorial is part of the issue “The City of Flows: Urban Planning of Environmental Flows”, edited by Rob Roggema
(Cittaideale, The Netherlands/Hanze University Groningen, The Netherlands).

© 2019 by the author; licensee Cogitatio (Lisbon, Portugal). This article is licensed under a Creative Commons Attribu-
tion 4.0 International License (CC BY).

1. Introduction: Brief History of Urban Metabolism

When we think about flows in the city the term urban
metabolism is often used. Like our body, the city is seen
as an organism which requires resources to function, and
the way these resources are used to serve all different
functions of the city, and to which waste flows this leads,
determines the metabolism of the body, and translated
to urban flows, the urban metabolism. The first to point
at the role that a flow, in this case the flow of water, plays
in the urban fabric was Abel Wolman. He calculated the
size of the water flows that flew through the city and dis-
cussed how this flow could be managed more efficiently
and more sustainable (Wolman, 1965). Some decades
later the discussion about pollution of the urban environ-
ment led to the need to understand the urban pollutants
better and their influence on the flows of the city. Air
could be polluted and could pollute soils and water, pol-
luted water could pollute food systems and have a pro-
found impact on human health. It was therefore essen-
tial to develop understanding about how these flows in
the city behaved, how big they were and how they influ-
enced the quality of life, and how they produced waste

streams in the form of pollution. An important insight
was offered when urban flows became part of an eco-
logical conceptual model (Van Leeuwen, 1981). In this
model the aims for a sustainable management of flows in
the city was established. In a so-called eco-device model
(Figure 1) the incoming and outgoing flows were symbol-
ized, as well as the flows that were prevented from en-
tering the area or leaving. This way, an abstraction of the
flows of water, energy and materials could be given, and
determine if the system was performing ecologically well
or not.

This abstract model has been modified and further
elaborated in order to illustrate the flows in greater de-
tail and also show the external factors of the system, such
as climate change, that determine the context of the
“extended urban metabolism model” (Newman, 1999).
Though Peter Newman has put the model in practice, es-
pecially in traffic and mobility plans, working with the
parameters in an integrated way to create a spatial per-
spective remained a challenge. Jón Kristinsson invented
a three-dimensional model (Figure 2, left) in which, for
every layer, the specific flows were symbolized as in or
outgoing flows, which could re-enter the system at an-

Urban Planning, 2019, Volume 4, Issue 1, Pages 106–112 106

Source problems:

in out

not outnot in

Deple�on
Degrada�on

Exhaust problems:

Pollu�on
Degrada�on

Internal problems:

Damage to
-health
Plants & animals
Func�ons

Figure 1. Eco-device model (IN–Not IN; OUT–not OUT). Source: After Van Leeuwen (1981).

other level. This way a comprehensive 3D-model of a
city could be drawn, and the city seen as an ecosys-
tem itself (Tomásek, 1979). The levels Kristinsson deter-
mined were the abiotic, biotic, urban and atmospheric
layers (Kristinsson, 2012). Nowadays, more layers could
and should be added to this systemic image (Figure 2,
right), as demonstrated by van Timmeren and Henriquez
(2015). The exchange of flows between more layers will
open up the possibilities to close cycles and become a
more sustainable urban ecosystem. A direct link can be
established here with thinking that takes place around
the theme of Smart Cities.

The ecosystem model is reduced to few levels (earth,
city, networks) in the new model (new linkages and
potentials to connect and exchange flows, materials,
streams), and lacks the (a)biotic layers at all. When these
would be integrated in the model a more comprehen-
sive model would emerge, hence consist of the abiotic,
biotic, user, interface, address, network, city, cloud and
earth layers.

Where most of Kristinsson’s (2012) work focuses on
the building itself, trying to optimize the indoor climate
and direct environment of the building using technolog-
ical innovations that make use of the different available

Figure 2. Kristinsson’s (2012) 3D-model of the city as an ecosystem (left); van Timmeren and Henriquez’ (2015) “the Stack”
layers including recent digital additions (right).

Urban Planning, 2019, Volume 4, Issue 1, Pages 106–112 107

flows in the vicinity and aim to close resource and waste
cycles as good as possible, “until the good (urban) trav-
eler leaves no trace”, at the scale of the city as a whole
additional connections, exchange and gains can be har-
vested. In the Rotterdam Biennale 2014, curated by Dirk
Sijmons, this has been investigated (Figure 3) under the
title Urban by Nature (Brugmans & Strien, 2014), and
design-led projects have shown that large benefits can
be by connecting the waste streams of certain flows
to the resource demands of others at the regional ur-
ban scale (Gemeente Rotterdam, IABR, FABRIC, JCFO, &
TNO, 2014).

Overlooking 50-odd years of scientific research,
thinking, academic education, designing and innovating
around the topic of urban flows, several aspects pre-
sented themselves as key components. The quantifica-
tion of urban flows, the ambition to close cycles and min-
imize waste flows, the systemic approach, and the im-
plications for the spatial configuration of the city are re-
curring subjects. However, the dominance which could
be expected of design-led approaches did not come to
total fruition. At the end of the day urban flows must
be quantified, in order to assess their performance and
this seems the dominant paradigm. Instead of looking
at the size of flows only, ore aspects require synergy,
something that can be easily achieved through design.
The synergies between livability, design, urban flows, as-
sessment tools and sustainability has been extensively
investigated (Tillie, 2018). Implementation of synergetic
thinking should now be a priority, and it is necessary that
the integration and sustainability of urban flow systems

should shape the city. Consciously, and not as an invisible
unexpected add-on to our cities. Integrated urban flows
should be designed to lead to attractive places, in which
the brilliance of the systems has become visible, can be
witnessed and experienced by residents, and where new
resources are celebrated.

2. Thinking in Nexuses

So far, the majority of academic work has been ori-
ented towards quantification of flows, assessment tools,
and determining what one flow needs from another
to operate? Do we have enough water for bioenergy,
how much electricity is needed for desalination? These
types of questions are mainstream, often focusing on
only one urban flow. In recent decades the energy-
water nexus has received the majority of the atten-
tion, as can be witnessed by a broad range, but not
exhaustive, of literature shown here (Bauer, Philbrick,
& Vallario, 2014; Byers, Hall, & Amezaga, 2014; Connor
& Koncagül, 2014; Cooley & Wilkinson, 2012; Davies,
Kyle, & Edmonds, 2013; Gleick, 1994; Halstead, Kober,
& van der Zwaan, 2014; Henthorne, 2009; Inhaber,
2004; Kohli & Frenken, 2011; Koulouri & Moccia, 2014;
Lavelle & Grose, 2013; Macknick, Newmark, Heath, &
Hallett, 2012; Macknick, Sattler, Averyt, Clemmer, &
Rogers, 2012; Mielke, Diaz Anadon, & Narayanamurti,
2010; Mitra & Bhattacharya, 2012; Plappaly & Lienhard,
2012; Radcliffe, 2018; Rodriguez, Delgado, DeLaquil, &
Sohns, 2013; Sanders & Webber, 2013; Spang, Moomaw,
Gallagher, Kirshen, & Marks, 2014; Stiegel et al., 2009; US

Figure 3. Urban metabolism model. Source: Dirk Sijmons/Jutta Raith (Gemeente Rotterdam et al., 2014).

Urban Planning, 2019, Volume 4, Issue 1, Pages 106–112 108

Department of Energy, 2006; Wang, 2013; Water in the
West, 2013; Webber, 2008; World Energy Council, 2010).

The nexus of water and food has been investigated in
the agricultural literature, while the energy-food nexus is
less well researched (ISIS, 2013; WISIONS, 2007) and very
few linkages are made between food, energy and water
and ecosystems (UNECE & KTH, 2014).

Only recently integrated thinking about water, en-
ergy and food emerged as the food-energy-water nexus
(Barrett, 2014; Bazilian et al., 2011; Bizikova, Roy,
Swanson, Venema, & McCandless, 2013; BMU, 2012;
Ferroukhi et al., 2015; Flammini, Puri, Pluschke, &
Dubois, 2014; Granit et al., 2013; Hanlon et al., 2013;
Hoff, 2011; Mohtar & Daher, 2012, 2013; Shannak,
Mabrey, & Vittorio, 2018; SEI, 2011; World Economic
Forum, 2011). Especially after the Bonn2011 meeting
the research agenda sparked, and new investigations oc-
curred and reached the academic journals. The majority
of these research outputs are focus on quantifying the
flows, developing assessment tools and/or aim to define
the relationship quantitively between two or more of the
flows. The implications of different sizes, relationships
and amounts of flows for the city are less well researched.
A design-led approach is rare, and this may be one of the
reasons it is very difficult to amend the systems of wa-
ter, energy and food to establish more integrated, sus-
tainable and resilient urban systems (GIZ & ICLEI, 2014).

3. The Thematic Issue

The focus on quantification of urban flows is, on the
one hand, needed to understand what we are talking
in the first place. It does matter with how much wa-
ter we have to deal in the city, how much energy is
required, or how much food must be grown to feed
the population. However, on the other hand understand
quantity only is not enough. Reduced amounts of flows
must also be integrated in the spatial context of the city,
towns and landscape. Therefore, this thematic issue of
Urban Planning features articles that illuminate the pos-
sibilities of design-led approaches to inclusion of urban
flows in the city. To set the scene, Roggema (2019) starts
with sketching the current context of disruptive develop-
ments, which influence the context and the spatial op-
tions in the city. The space available and the amounts of
networks for unexpected change determines the adap-
tivity of systems, and the possibility to introduce coun-
terintuitive solutions. Yan and Roggema (2019) focus on
design-led approaches for the food-energy-water nexus,
and integrate spatial, governance and appraisal aspects
of the nexus. Han and Keeffe (2019) focus on a very inter-
esting flow, the move of urban forests through the city.
In their article, Galan and Perrotti (2019) highlight the
opportunities for sustainable metabolism at the regional
level. The way people can be involved and given a larger
stake in their consumption of basic flows is the subject
in McLean and Roggema (2019), while a different per-
spective on governance to improve urban metabolism,

increasing accountability in strategic planning, is given in
Zengerling (2019).

This thematic issue brings together insights and per-
spectives on the “city of flows”, an orientation on the
possibilities to change the spatial design for the city as a
result of choices made for flow systems. This design-led
thinking is, so-far, underestimated in realizing a resilient
system of flows in urban environments. Even in acquir-
ing academic outputs for this thematic issue, it proved
to be not easy to collect an abundant number of arti-
cles. There is still a long way to go, especially because
the quantification, assessing and defining of urban flows
will not easily lead to implementation, and hence to a
more resilient and sustainable city. The way design ap-
proaches can visualize solutions and propose unprece-
dented and innovative solutions is unmet by most cur-
rent published research.

4. Conclusion: Future?

State of the art literature shows that most research fo-
cuses recently on the food-energy-water nexus. While
in building research materials form a substantial body
of knowledge, the use of waste and materials at the ur-
ban design level is not very common. Therefore, it is sug-
gested to add and integrate these flows to the model. Fi-
nally, the rapid development of data collection, analysis,
data-driven design and the use of data in planning our
cities (Smart Cities), would justify starting thinking about
integrating data in the urban metabolism model, despite
data being often non-physical.

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Urban Planning, 2019, Volume 4, Issue 1, Pages 106–112 111

About the Author

Rob Roggema (PhD) is Professor of Sustainable Spatial Transformations at the Knowledge Centre
Noorderruimte, Hanze University Groningen. He is a landscape architect and an internationally
renowned design-expert on sustainable urbanism, climate adaptation, energy landscapes and urban
agriculture. He has previously held positions at universities in the Netherlands and Australia, State
and Municipal governments and design consultancies. Rob developed the Swarm Planning concept, a
dynamic way of planning the city for future adaptation to the impacts of climate change.le of urban
planning and architecture in the daily lives of asylum seekers and their future trajectories.

Urban Planning, 2019, Volume 4, Issue 1, Pages 106–112 112

External resources:

1-

https://scialert.net/fulltext/?doi=jest.2009.120.132

2-

https://www.worldresearchlibrary.org/up_proc/pdf/1058-15083262781-13

3- Get a third resource about urban metabolism in Jeddah, Saudi Arabia