Draft text. Final text has been published in:

Van Bueren, E. (2012). Introduction. In: Van Bueren, E., Van Bohemen, 

H.,  Itard,  L.,  &  Visscher,  H.  (eds.)  (2012).  Sustainable  urban  environ‐

ments: an ecosystem approach, Dordrecht: Springer, pp. 1‐13. 

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1 Introduction

Ellen van Bueren

Delft University of Technology

Abstract The built environment is an important factor for sustainable develop-

ment. Our cities offer many challenges, but also hold the key to a more sustainable

steady state. This chapter introduces you to the content of this book, in which we

consider the built environment as an ecosystem. Using an ecosystem approach

helps you to understand the numerous interdependent relationships between mul-

tiple spatial scales, flows, time zones, disciplines and actors. This understanding

will help you to analyse problems that you come across when you try to make the

urban environment a better place, and to identify appropriate solutions to the chal-

lenges faced.

1.1 The built environment: problem and solution

The built environment is the place where the three pillars of sustainable develop-

ment, people, planet and profit, meet. Buildings and cities are places where peo-

ple, live, love and work. This book starts with some notions and facts and figures

about how the built environment influences the delicate balance of our earth eco-

systems from a people, planet and profit point of view.

As from 2007, half of the world population lives in cities and urbanization is

expected to continue. In Europe and in North and South America, already 75% of

the population lives in cities. In Asia and Africa, 35% of the people live in urban

areas, but urbanisation is rapidly growing in these continents, and it is expected

that already in 2030 this percentage will have increased to 50% (WWI 2007). In

developing countries, the drift to the city exceeds the capacity of these cities to ac-

commodate the new citizens. The cities do not fulfil the promise to a better life

which made people leave their rural villages. Of the 3 billion citizens in the world,

about one billion lives in slums, and this figure is expected to double by 2030

(ibid.).

A significant part, 40% of the materials extracted from our planet are stored in

buildings and infrastructures (Kibert et al. 2002). The construction industry pro-

duces nearly 40% of all human-generated waste (Sawin and Hughes 2007). Cities

are built in catchment areas, or along rivers, and influence the hydrological cycle.

The paved surfaces are impermeable to rainwater. Our use of water for industry

and sanitation degrade the water quality. By impacting the hydrological cycle, cit-

3

ies also affect our climate. Cities are stone, dry heat islands that absorb warmth.

The density of the urban structures leaves little room for natural ventilation in the

streets and squares to cool down and diffuse the pollutants in the air. Cities are

connected to other cities by roads, railway and airports. To support life in cities,

food is grown and imported from all over the world along these transport lines.

The energy needed to operate the buildings, infrastructures and transport modes,

mostly consists of non-renewable, fossil sources and is transported over long dis-

tances. Road congestion makes cities inaccessible and causes air and noise pollu-

tion. About 40% of the world’s greenhouse gases emitted are related to building,

construction and transportation (ref.). About 25% of total energy use is used for

operating buildings (ref.).

But cities are also the centres our economy. Exactly because they bring so

many people together, they also generate economic activity, such as shops, offices

and services. The hustle and bustle attracts new citizens and activities that have to

be accommodated. A considerable part of our capital is invested in the design,

construction and management of our buildings, infrastructures, and urban struc-

tures. Buildings and infrastructure developments offer a relatively safe investment

for institutional funds. About 5-15% of GDP is earned in building and construc-

tion; the construction sector employs about 5-10% of all employees (OECD 2003).

On a micro level, citizens pay a substantial part of their income to rent or mort-

gage.

These figures give an idea of how built environments, and especially cities, affect

people, planet and profit. But it is of no use to think in cities in terms of good or

bad. Cities are there, they are growing and increasing in number, the built envi-

ronment is expanding, and this is something that we should take as a starting point

for our attempts to make them sustainable.

The built environment can offer a significant contribution to sustainable devel-

opment. The following examples will give you an idea. To combat climate

change, buildings can be made energy efficient or even energy producing, like the

energy producing dance floor in a dance club in Rotterdam. To reduce land use,

cities can be built in high densities. In turn, high densities make public transport

economically feasible, which reduces car dependency and increases travel oppor-

tunities for citizens. The depletion of natural resources can be slowed down by re-

using buildings and constructions or the materials that they are made of. Human

health can be improved by carefully selecting materials used in buildings and by

improving ventilation of buildings. After all, we spend 90% of our time indoors,

and indoor climate can be an important determinant of human health. In addition,

shifts from car use to more sustainable modes of transport and measures that re-

duce congestion contribute to the air quality outdoors. Putting vegetation on roofs

of buildings reduces the heating of these roofs and buildings during a day of sun-

shine and thus the need for air conditioning; while at night the evaporation of the

vegetation helps to cool down the cities. In addition, green roofs slow down rain-

water runoff, purifies the air by binding particulate matter and carbon emissions

4

and last but not least; they offer a living space for plants, birds and insects and

make the city a nicer place.

These examples show that the built environment holds various keys to a more

sustainable planet. At the same time, the examples show that there are many inter-

dependencies between the different problems and solutions. The green roof illus-

trates the many relationships that exist between problems and solutions. It is an

example of how one solution can positively impact several problems, such as the

urban heat island, water management, air quality, biodiversity, and liveability. The

green roof demonstrates how different spatial scales are connected. It is a solution

that is implemented on the level of a building, but many green roofs together can

impact temperature and humidity on city level. In addition, the green roof shows

that the built environment affects multiple values, such as health, ecology, econo-

my, liveability, and spatial quality.

1.2 Analysing the built environment: an ecosystem approach

The introduction showed how the built environment, and cities in particular, can

impact the environment positively or negatively. But where should we begin with

changing unsustainable situations into sustainable ones? There is an indefinite

number of variables present in the built environment, ranging from buildings, to

land prices and endangered species. These variables are also somehow related, di-

rectly or indirectly. High land prices make real estate development profitable,

which may further destroy the living area of species. There are numerous of such

causal chains, and each variable is part of multiple causal chains. As a result,

cause-and-effect relationships are complex and intractable. In such a chaos of var-

iables, it is difficult to know where to intervene and to predict how interventions

will work out.

The ecosystems approach is a theoretical approach that helps us to structure the

chaotic web of variables and relationships. The ecosystems approach has its ori-

gins in biology. It helped biologists to understand the complexity of organisms

and the delicate relationship between populations and their environment. In this

book we will use this approach to explain the problems and opportunities for sus-

tainability in the built environment. Essence of the approach is that it cuts up cha-

os or complexity into smaller pieces of chaos.

The ecosystems approach suggests that –analytically– we can distinguish sub-

systems that together constitute this one big system. Because subsystems are

smaller, i.e. they consist of less variables and interrelationships; it is easier to get

to know them or to develop some understanding of the mechanisms at work in the

system. In turn, subsystems can be split up into smaller subsystems. Where to

draw the line between systems and subsystems, is thus purely a theoretical exer-

cise. However, the chosen system boundaries are of great influence on the prob-

lem diagnosis and potential solutions. For example, when you study sea level rise

5

in low nations, such as the Netherlands or some tropical island groups as the Mal-

dives, you may come to the conclusion that sea level rise is a problem that requires

investing in higher levees. When you study sea level rise on a regional level, you

may come to the conclusion that it could be wiser to invest in the reallocation of

human settlements.

In the built environment, there are a several ways to define system boundaries.

Some common demarcations will be introduced.

Spatial scales

The first is based on how designers reduce complexity. They bring order to the

built environment by distinguishing spatial scales. The building is usually the low-

est scale distinguished, although buildings have smaller units and rooms, and con-

sist of building components and materials. Buildings are situated in neighbour-

hoods, neighbourhoods are situated in districts, districts in cities and towns, cities

and towns in regions, regions in nations, and nations in continents. At the building

level, the architect largely determines the design, while at higher levels urban

planners, transport infrastructure planners and landscape architects influence the

design. There are many relationships between the spatial scales. Design choices at

one scale influence the design choices on another scale. For example, the decision

for a central heat delivery system in a newly built residential district conflicts with

decentralised solutions such as combined heat-power installations at individual

homes. Usually, decisions at higher spatial scales constrain or condition the deci-

sions at lower scales.

Figure 1.1 shows how actions at a low spatial scale, the decision to heat

or cool a room to become comfortable, contributes to emissions to air and soil in

the neighbourhood and district, and to exhaustion of energy sources and climate

change on a global level.

Fig. 1.1 Relationships between scales (Duijvestein 1996)

6

Lifecycle stages

A second often used demarcation in the design and decision-making about the

built environment takes the lifecycle of the built environment as a starting point.

Buildings, areas and infrastructures are initiated, designed, constructed, used, ren-

ovated and in some cases eventually demolished. These lifecycle stages all have

their own temporal and social dynamics, as is illustrated in figure 2. The time that

each stage takes can differ dramatically. Designs are made in weeks or months,

while the use and maintenance stage of buildings and constructions can range

from decades to centuries. The social dynamics results from the variety of actors

involved in each stage of life; each stage has its own stakeholders. From an eco-

systems point of view, designers are challenged to take the entire lifecycle into ac-

count, even when they are involved only in one stage. A method as lifecycle anal-

ysis helps to take the environmental performance of building materials from cradle

to grave into account when designing buildings or larger scale developments. Cra-

dle to cradle design goes a step further and challenges designers to only produce

products −including buildings− that consist of components that can be decom-

posed and reused; the circle of life becomes a closed system in which there are no

leakages in forms of inefficiencies, spillages, or waste. However, also processes of

decomposition and reuse need energy.

Participant Activities Time

Government

Urban planners

Architects

Contractor

Users

Users

Contractor

Contractors

Initiative

Location selection

Design

Construction

Use and upkeep

Renovation

(Re)use

Demolition

Hours

Days

Weeks

Months

Years

Weeks

Years

Days

Fig. 2 Activities, participants and time at different lifecycle stages (Source

figure: Kees Duijvestein)

Flows

A third way in which system boundaries can be defined is by looking at the flows

that are used for the processes in the built environment. If you look at cities, or

7

parts of it, from a system perspective an input-throughput-output perspective, than

you see that cities are open systems. Processes in the built environment need in-

put: they use water, energy and materials. Cities need water for functions as drink-

ing, sanitation, industry and for maintaining a liveable climate, they need energy

for functions as transport, indoor climate control and working, and they need ma-

terials to construct and maintain the built environment. The throughput time of

these resources can differ dramatically. The resources come out of the system in a

different or degraded form: the characteristics have changed and/or quality is low-

er.

Also usage of the resources emits pollutants to air, water and soil. These

can negatively impact the city itself, but may also impact systems at a higher level,

at a regional or even at a global level.

From this flow perspective, making cities sustainable is about making ef-

ficient use of these resources and trying to upkeep the quality of the resources dur-

ing and after usage. For example, sewage water can be treated to be reused as

drinking water, but industrial ‘waste’ heat is not powerful enough to be used as an

energy source for industrial processes, but can be used to heat the houses in a

nearby residential area. Strategies to minimize the use of flows and to make more

efficient use of flows are about good housekeeping and closing loops.

IN Building OUTbuilding materials

energy

water

flue gas (after 1 min.)heat (after 10 hour)

waste water (after 10 min.)

demolition rubble (after 100 years)

Fig. 3 Input, throughput and output of flows in the built environment (Source

figure: Kees Duijvestein)

In addition to the input-throughput-output perspective, the Ecodevice Model is a

model that emphasizes the capacity of the urban system to resist and retain flows.

To increase efficiency of flows and to reduce the input of flows, urban areas

should try to make optimal use of flows that are already present in the system, in

other words, resist the influx of flows, and retain flows in the system as long as

possible. The catchment and reuse of rainwater is an example of how the input of

water can be reduced. Improvement of the retention capacity of urban surfaces by

green roofs, permeable tiles and adding green structures is an example of how the

retention capacity of urban areas can be improved. The figure also shows that

flows can be analysed at different spatial scales: at the regional, city, district and

building level.

8

region

city

district

building

IN

NOT IN

OUT

NOT OUT

Fig. 4 The Ecodevice Model (Source: Tjallingii 1996: 197)

Conclusion

The above distinctions of subsystems in the built environment are thus based on

spatial scale, lifecycle, and flows. There are many other demarcations possible,

that are each equally valid. Analysing the built environment with an ecosystems

approach helps to get a grip on the complex web of causal relationships.

1.3 What is ‘sustainable’ is influenced by analytical choices

When analysing the built environment as a system, the results of the analysis de-

pend on the system boundaries defined. Each definition of boundaries leads to a

different diagnosis of problems and solutions with regards to sustainability. As a

consequence, there is no neutral definition of ‘sustainability’. The analytical point

of view adopted, the subsystem boundaries defined, determines what problems

and opportunities for improvement are identified. Questions that ask for solutions

cannot be answered unambiguously. Examples of such questions are: Should I

construct my house of timber or concrete? Is it better to commute by car or by

public transport? Should I have a garden and grow my own crops or should I live

in a high rise apartment, using less space? The answer to all these questions is: it

depends. It depends on how you define your subsystem boundaries and which val-

ues you want to enhance within these boundaries.

How subsystems are demarcated depends on the people that define the

boundaries, the values they prefer and the purpose for which they are defined. For

example, civil engineers will most likely take the level of the construction as

boundary for their analysis, and will look at the materials needed to construct a

house, road or bridge that will be solid and safe throughout its lifetime. Architects

9

may focus on the design and construction stage of the lifecycle of buildings, and

will do so from a mixture of aesthetic and functional considerations. Facility man-

agers, responsible for the exploitation, operation and maintenance of buildings and

constructions may be more focused on the use stage of the building, and may care

especially about maintenance costs and energy needed to operate the building

throughout the lifetime. How people set boundaries, thus depends on the role they

play in the built environment –which organisation or institute do they represent-

and on how they were trained. Each profession has its own set of methods and

tools to diagnose, analyse and solve problems. For example, civil engineers typi-

cally cut up problems in parts that can be solved, while designers as architects and

urban planners tend to design more intuitively from a holistic point of view.

Sustainability contains multiple values: people, planet and profit repre-

sent respectively values as democracy and social justice, ecological values and

economic values. But also within these three dimensions, there are multiple values

present, and these values may be competing or conflicting. For example, making

places more pleasant to live in for residents may imply a deterioration of living

conditions of people in other places or in the future; improving health care and

medication may lead to ecological risks because of accumulation of medicinal

substances emitted to water; large-scale wind parks may disrupt routes of migrato-

ry birds. Designing the built environment is therefore also about setting priorities.

In the design, some values are considered more important than others. The chal-

lenge for designers is to find out which values they want to support, and how they

can support them. They can look for creative solutions that support multiple val-

ues and that reduce or resolve conflicting values.

As mentioned, the purpose of the analysis also plays a role in defining the

system boundaries. When the purpose is to make buildings ‘carbon neutral’, it

naturally follows that the building is the system analysed for its energy perfor-

mance throughout its lifecycle. When the purpose is to reduce car use for short

distances, the geographical boundaries may cover an area of about 5 km, while the

social-psychological system studied may include all those factors that influence

travel behaviour, ranging from individual preferences to weather conditions and

financial considerations.

Making the built environment sustainable is thus a challenge that can be

approached in different ways, each having their advantages and disadvantages.

This book presents an analytical framework that helps you –as (future) profession-

als– to appropriately demarcate the boundaries within which a problem can be an-

alysed and solved; i.e. the book shows how problems and solutions at one spatial

scale are always connected with problems and solutions on higher and lower

scales; how some problems can better be solved at a regional level, while other

problems can better be solved on a local level; how some problems should be ad-

dressed in connection to other problems, involving the knowledge and expertise of

other disciplines and professions; how solutions to one problem will have positive

or negative consequences for other problems, addressed by other stakeholders, at

other places and at other times; how some solutions–such as the green roof–

address a range of problems that affect multiple subsystems at multiple spatial

scales. In this book, we will remind you of these interconnections between subsys-

10

tems, scales and time whenever appropriate, by pointing at relationships between

the analysis or solution presented and problems and solutions at other spatial

scales, within other flows or within other lifecycle stages.

1.4 Setting the boundaries in this book

The focus of this book is on the built environment, ranging from buildings and

small settlements, villages and town to cities and metropolitan areas. This book

will explore the basics of how buildings and constructions and the servicing and

connecting infrastructures, whether they are built in high or low numbers and den-

sities, affect our ecosystems. Size and structure of the built environment become

important variables when discussing the impact of the effects and the appropriate-

ness of certain solutions, designs and technologies.

The book represents knowledge that applies to industrialized countries.

Of course there are geographical, cultural and institutional differences between

these countries. But this book does not intend to present tailor-made solutions for

specific areas. Instead it introduces a way of thinking (the ecosystems approach), a

way of working (methods and tools) as well as some fundamental understanding

of the subsystems that matter with regards to the sustainability of the built envi-

ronment. Reading this book should help (future) designers and other (future) pro-

fessionals involved in the design and management of the built environment to rec-

ognise and make use of opportunities for contributing to sustainability.

There are three important choices underlying the structure and content of

this book. First, the book adopts an ecosystems approach to the sustainability chal-

lenge of built environment. The built environment can be considered as an ecosys-

tem that needs to balance input, output, use and extraction of resources such as

materials, water, and energy. To accommodate the use of these resources, man

created all sorts of infrastructures, for example, for sewage, electricity and waste

disposal. These resources are thus part of more specialized systems or subsystems

that together constitute the built environment. In this book, you are introduced to

some important subsystems or flows including the infrastructure to transport them

−partly or entirely manmade− that influence the sustainability performance of the

built environment: urban ecology, water, energy, materials and transport.

This brings us to the second choice of this book. The book is based on a

design perspective. To improve the sustainability of the built environment, chang-

es have to be made in the subsystems of which the built environment is made up.

When designing or redesigning the built environment, these subsystems should be

taken into account. How these subsystems are used within the built environment

affects the balance within these subsystems and of the bigger system that they are

part of: the built environment. A design perspective differs from a purely analyti-

cal perspective. The book not just intends to analyse problems, but aims to solve

them as well, or at least present promising directions for problem solving. By

providing the reader of this book with basic knowledge of problems and ways –

11

methods, tools- to address these problems, the reader is able to recognise, analyse

and resolve problems that come up in his or her professional life.

The third choice, then, is to take the environmental dimension of sustain-

ability as a leading focus. The size of the challenge, in terms of use, degradation,

pollution and exhaustion of resources is enormous and environmental sustainabil-

ity is a condition for achieving goals in the field of economy and social justice.

Also, this choice acknowledges that the instruments available to the audience of

this book, advanced students and professionals with an interest in design of the

built environment, are mostly of a physical nature. The instruments shape or re-

shape the built environment and the way resources are used, and by doing so, they

can contribute to social and economic changes as well.

1.5 Outline of the book

The structural choices have resulted in the following contents of the book, as visu-

alized in figure 1.5.

Chapter 2 starts with an introduction to ecosystems thinking. Chapter 3 to

7 present the natural resources or flows that together constitute the built environ-

ment. Chapter 3 focuses on urban ecology; the presence and diversity of flora and

fauna in urban environments. Chapters 4, 5 and 6 respectively introduce the flows

that are essential for the built environment: water, energy and materials. These

flows of natural resources are accommodated by man-made technologies and in-

frastructures and together they form subsystems in the built environment. Chapter

7 discusses an entirely man-made system: that of the urban transport. Although

these chapters entirely focus on specific subsystems, they will pay attention to re-

lationships with other subsystems when appropriate.

Chapters 8 and 9 present how these flows and subsystems influence hu-

man living conditions in the built environment. Chapter 8 discusses effects of the-

se subsystems on air quality and human health, indoors and outdoors. Chapter 9

presents what liveability, the well-being, of citizens is about and how it is affected

by the built environment.

Chapter 10, 11 and 12 focus on designing sustainable built environments.

Chapter 10 presents general strategies for environmental design. Chapter 11 intro-

duces some specific and often used tools for integrated design. Chapter 12 shows

what these strategies and tools may bring us. It presents and discusses some prom-

ising holistic designs.

Unfortunately, being able to make sustainable designs or design choices

is no guarantee that these designs are realized. Chapter 13 discusses the tools of

government that can be used in support of a sustainable built environment. In ad-

dition, chapter 14 presents the institutional challenges that hamper the design and

implementation of sustainable solutions and discusses how public and private ac-

tors can contribute to a sustainable built environment.

Chapter 15 concludes with a reflection on the material presented and an

outlook for the future. In particular it focuses on recurring tradeoffs and dilemmas

12

that designers face when looking for sustainable solutions. It illustrates how the

knowledge in the book can be used to deal with these choices. Also, it presents

promising paths to a sustainable built environment.

Figure 1.5 Schematic overview of the book contents

Questions 1. Why is it worthwhile to focus on cities and urban development when dis-

cussing sustainable development?

2. How can the ecosystems approach be of help when you want to support

sustainable development?

3. Architects sometimes argue that the Egyptian piramids are an excellent

example of sustainable building. List arguments supporting and opposing

this statement and refer to different subsystems, flows, spatial and time

scales. Which side do you take and why?

4. p.m.

5. p.m.

References

Duivestein CJA (1997). Ecologisch Bouwen Delft.

Kibert, CJ et al (2002). Construction ecology: nature as the basis for green build-

ings, Spon Press.

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Sawing JL, Hughes K (2007). Energizing cities. In: the World Watch Insti-

tute,State of the world 2007: our Urban future, The World Watch Institute,

Washington DC, p.92.

Van Leeuwen CG (1973). Oecologie en natuurtechniek, Natuur en Landschap 27,

52-67

Van Leeuwen CG (1981). Ecologie en natuurtechniek, 10-5. Tijdschrift KNHM

92, 61-67, 99-106, 155-156, 255-262, 297-306, KNHM Arnhem, in Dutch.

Van Wirdum G (1982). Design for a land-ecological survey of nature protection.

In: Perspectives in landscape ecology, pp.245-251, Pudoc, Wageningen.

UN: United Nations (2009)

UNEP: United Nations Environment Programme (2009)

UN: United Nations 2010

WWI: The World Watch Institute (2007) State of the World 2007, Our Urban Fu-

ture, The World Watch Institute, Washington DC