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Sustainable cities


The population of our Planet recently hit the 7 billion inhabitants milestone and, since 2008, the percentage of urban population surpassed the one of the rural population. According to the UN, this percentage is going to increase even more in the future. Therefore, it makes sense to analyse how today’s cities, and also the new ones that will be created, will face the challenges of the future.


Many people claim that nowadays cities are less environmentally friendly than villages, that their ecological footprint is higher and that large agglomerations will not manage to become greener. Looking at most of the world’s cities, this statement seems to be confirmed. As many cities have become major consumers and distributors of goods and services, they are rather draining the resources out of surrounding regions. Thus, given the large dependencies generated by trade, the ecological footprint of cities extends well beyond their physical location.


However, there are examples that can contradict this and these are exactly the ones that should be taken as models. Because in a crowded city there is more than just wasted resources and huge amounts of garbage; there are advantages that need to be built on, as for instance, a close location of people and resources (thus allowing saving on energy or transportation).



What is a sustainable city?


The term “sustainable city” has become increasingly used in today’s society, especially in the same context where other notions, such as sustainable development, sustainable living, green energy, etc, are being addressed. However, the concept is not new. It was first pinned down as “ecocity” in 1987 by Richard Register in his book “Ecocity Berkeley: Building Cities for a Healthy Future”: simply put, an ecocity is an ecologically healthy city. In other words, a city that has a minimum impact on the environment, weather we look at inputs (energy, water, products, etc) or outputs (waste, waste water, heat, noise, etc).


Like in the case of many “modern” concepts today, the several existing definitions are neither unique, nor completely agreed upon. Experts are still debating on the components that ought to be included in this sustainability context. Elements such as low carbon footprint, recycling and composting, renewable energies, efficient land use and similar are all on the table, although there is no exact list as to what should be included, nor is there a clear limit beyond which a city implementing (a part of) these elements is declared sustainable. In fact, it is much easier to point out the things that should not be done, like pollution or waste dumping, than to set a threshold of good practices that can guarantee sustainability.


The Institute for Sustainable Communities defines a sustainable community as “one that is economically, environmentally, and socially healthy and resilient. It meets challenges through integrated solutions rather than through fragmented approaches that meet one of those goals at the expense of the others. And it takes a long-term perspective - one that is focused on both the present and future, well beyond the next budget or election cycle. As a result, a sustainable community manages its human, natural, and financial resources to meet current needs while ensuring that adequate resources are equitably available for future generations. It seeks:


·         A better quality of life for the whole community without compromising the wellbeing of other communities

·         Healthy ecosystems

·         Effective governance supported by meaningful and broad-based citizen participation.”



Dimensions of sustainability


As already mentioned, there are many actions a city can take in order to become more sustainable. Different examples can be easily found at a click of the mouse. The following list is just a selection from Wikipedia:


·         Agricultural plots within the city (suburbs or centre). This reduces the distance food has to travel from field to fork

·         Renewable energy sources, such as wind turbines, solar panels, or bio-gas created from sewage. Cities provide economies of scale that make such energy sources viable

·         Energy conservation systems/devices

·         Various methods to reduce the “heat island effect”, which can make urban areas several degrees warmer than surrounding areas: planting trees and lightening surface colours, natural ventilation systems, an increase in water features, and green spaces equalling at least 20% of the city's surface

·         Green roofs

·         Xeriscaping - garden and landscape design for water conservation

·         Improved public transport and increased facilities for pedestrians and non-motorized vehicles, to reduce car emissions. This requires a radically different approach to city planning, with integrated business, industrial, and residential zones

·         Sustainable transportation: using of a diversity of fuel-efficient transportation vehicles in order to reduce greenhouse emissions and diversity fuel demand. The use of alternative energy cars and wide spread instillation of refuelling stations has gained increasing notoriety. Also, the creation of centralized bike and walking paths remains a staple of the sustainable transportation movement

·         Optimal building density to make public transport viable but avoid the creation of urban heat islands.

·         Zero-energy buildings

·         Leadership in Energy and Environmental Design (LEED)-certified buildings: internationally recognized standard for whole-building sustainable design by identifying key areas of excellence including Sustainable Sites, Water Efficiency, Energy and Atmosphere, Materials and Resources, Indoor Environmental Quality, Locations & Linkages, Awareness and Education, Innovation in Design, Regional Priority

·         Sustainable urban drainage systems

·         Eco-industrial park, with the purpose to connect a number of firms and organizations to work together to decrease their environmental impact while simultaneously improving their economic performance, through collaboration in managing environmental and resource issues, such as energy, water, and materials

·         Walkable urbanism advocates housing for a diverse population, a full mix of uses, walkable streets, positive public space, integrated civic and commercial centres, transit orientation and accessible open space.



Building for the future


As the saying goes “Desperate times call for desperate measures”. In this case, “innovation” is the magic word. As the challenges faced by cities and the ones who inhabit them will only get more remarkable in the future, they can only be addressed by equally innovative and daring responses.


Steffen Lehmann introduced in his paper “Green Urbanism: Formulating a series of holistic principles”, 15 principles as a conceptual model and a framework for designing, building and operating urban settlements in the future. He argues that “the future of our societies is not just merely a technical matter of finding more eco-friendly energy solutions, but a question of holistic environmental and social sustainability and identifying principles for healthy communities.”


The principles are based on the triple-zero framework (zero fossil-fuel energy use, zero waste, zero emissions) and are given below:


1.      Climate and context: The city based on its climatic conditions, with appropriate responses to location and site context. What are the unique site constraints, climatic conditions and opportunities?

2.      Renewable energy for zero CO2 emissions: The city as a self-sufficient on-site energy producer, using decentralized district energy systems. How can energy be generated and supplied emission-free and in the most effective way?

3.      Zero-waste city: The zero-waste city as a circular, closed-loop eco-system. How to avoid the creation of waste in the first place – changing behaviour of consumption?

4.      Water: The city with closed urban water management and a high water quality. What is the situation in regard to the sustainable supply of potable drinking water?

5.      Landscape, gardens and urban biodiversity: The city that integrates landscapes, urban gardens and green roofs to maximize biodiversity. Which strategies can be applied to protect and maximize biodiversity and to re-introduce landscape and garden ideas back in the city, to ensure urban cooling?

6.      Sustainable transport and good public space: compact and poly-centric cities. The city of eco-mobility, with a good public space network and an efficient low-impact public transport system for post-fossil-fuel mobility. How can we get people out of their cars, to walk, cycle, and use public transport?

7.      Local and sustainable materials with less embodied energy: City construction using regional, local materials with less embodied energy and applying prefabricated modular systems. What kind of materials are locally available and appear in regional, vernacular architecture?

8.      Density and retrofitting of existing districts: The city with retrofitted districts, urban infill, and densification/intensification strategies for existing neighbourhoods. What are the opportunities to motivate people to move back to the city, closer to workplaces in the city centre?

9.      Green buildings and districts, using passive design principles: The city that applies deep green building design strategies and offers solar access for all new buildings. How can we best apply sustainable design and passive design principles in all their forms and for all buildings?

10.  Livability, healthy communities and mixed-use programs: The city with a special concern for affordable housing, mixed-use programs, and a healthy community. How does urban design recognize the particular need for affordable housing, to ensure a vibrant mix of society and multi-functional mixed-use programs?

11.  Local food and short supply chains: The city for local food supply, with high food security and urban agriculture. Which strategies can be applied to grow food locally in gardens, on roof tops and on small spaces in the city?

12.  Cultural heritages, identity and sense of place: The city of public health and cultural identity: a safe and healthy city, which is secure and just. How to maintain and enhance a city’s or region’s identity, unique character and valued urban heritage, avoiding interchangeable design that makes all cities look the same?

13.  Urban governance, leadership and best practice: The city applying best practice for urban governance and sustainable procurement methods. Which networks and skills can be activated and utilized through engaging the local community and key stakeholders, to ensure sustainable outcomes?

14.  Education, research and knowledge: The city with education and training for all in sustainable urban development. How to best raise awareness and change behaviour?

15.  Strategies for cities in developing countries: Particular sustainability strategies for cities in developing countries, harmonizing the impacts of rapid urbanization and globalization. What are the specific strategies and measurements we need to apply for basic low-cost solutions appropriate to cities in the developing world?



Examples of implementing sustainable practices


In the world we can find many good practice illustrations of sustainable solutions that cities have tried out. Naturally, these alternatives come at higher costs compared with regular ones. It comes then as no surprise to discover that most of the cities that have chosen greener options are located in developed countries, which could afford the associated expenses. An extensive list of cases can be explored under Sustainable Cities™, a database providing knowledge on sustainable planning initiatives in cities all over the world. The database looks at twelve categories: energy, transport, water, food, waste, green, social, buildings, masterplans, education, economy and health.


Below is a selection of cases from the above mentioned database, aimed at presenting a variety of interesting and often very innovating ideas for sustainable development in cities. Even if some of them may seem a little “out-there”, requiring sophisticated technical prerequisites, many are easily applicable to a large spectrum of urban settlements and can be taken as models of best practice.


Buildings: Zeist, the Netherlands


The new WWF Dutch headquarters have been transformed from a 1954 grim structure into a modern carbon-neutral building. Light has been brought to the core of the structure and the triple glazed windows of the facade allow for it to be adjusted according to season. The facade is covered with tiles made from local alluvial clay. Both electricity and hot water are provided by solar arrays. Other features include:

-          ceilings and walls covered in 100% biodegradable mud, absorbing moisture, providing a warm atmosphere and making for optimum regulation of the indoor climate;

-          mechanically extracted used air and natural ventilation in the facade for fresh air;

-          carpets made from recycled material, walls of recycled brick and all FSC certified wood;

-          a system of capillary tubes located under the mud wall circulate cold or hot water respectively through the building, connected to the heating system. This cools or heats the building, using thermal heating in winter and cool air in the summer, making radiators or air conditioning futile. If thermal and solar energy cannot provide enough heat, there is a backup installation which runs on carbon neutral linseed oil.


Economy: Sønderborg, Denmark


The municipality of Sønderborg initiated ProjectZero with the aim to become a powerful development nucleus in the clean-tech field. The ambition of the city is to create a CO2-neutral growth area in a region with a competitive commercial sector, enabling energy and climate solutions to be the motor of the new areas of growth. The Sønderborg area already has many science- and engineering-heavy companies (in fields like cooling, heating, lighting and process management, district heating, photovoltaic and hydrogen technologies, etc), giving it unique potential for this initiative. The city envisions reducing local energy consumption by 38% in as early as 2029 through self-sufficiency in sustainable energy technologies.


Energy: Liverpool, United Kingdom


Liverpool plans to become self-sufficient in CO2-neutral energy, as well to boost job creation, by using the potential that lies in algae, which will be grown in its many docks. This project is called Bio-Port Energy Free City and envisions a  cycle that involves algae production, glass making, cattle farming, greenhouse vegetable cultivation and, finally, large quantities of free energy and bio-oil that will be more than sufficient for heating homes, running the transport and making the city carbon neutral.


Energy: Torraca, southern Italy


The town of Torraca decided in 2007 to replace all its conventional public lighting with light emitting diodes (LEDs), powered by three solar energy stations. Thus, Torraca’s street illumination became entirely self-sufficient and 100% off-grid. By replacing a total of 700 lamps, the municipality achieved a 70% saving in urban energy and maintenance costs. Torraca has also built a factory in connection with these facilities in order to manufacture photovoltaic modules and research new advances in technology and infrastructure.


Energy: Reykjavik, Iceland


To date, Reykjavik fully exploited the advantages of its geologic location by using the abundant geothermal energy and hot springs from underground to generate electricity and to heat 95% of all buildings in the city. In fact, the city first started to use this potential in 1930. As it was expected, the use of this natural resource has greatly reduced its dependence on fossil fuels and in terms of CO2 emissions Reykjavik is now one of the cleanest cities in the world.


Food production and distribution in the city: Todmorden, United Kingdom


The small market town located 280 km from London has initiated an unusual project, called “Incredible Edible”. The project started with some herbs being planted in flower beds at one location and has been growing ever since by means of local commitment. Everywhere, from graveyards and car parks to the railway station, on roofs, even in disused rowing boats and wellington boots school playgrounds, vegetables, fruit trees and bushes have been planted with the aim to make sure that local foods are grown and eaten locally.


The project has also led to positive dialogue with public and private institutions. The major actors, such as companies, schools, hospital, farmers and the entire local community have become involved. All the town's schools have now laid out kitchen gardens in which the students grow their own vegetables. One of the initiatives extended the initial focus from vegetables to locally grown eggs. Given the positive outturn, the project has every chance to be a long-term one.


Green cities: Odense, Denmark


An architectural competition in Odense triggered the transformation of a former waste dump on the man-made island Stige Ø into an oasis, by covering it with a one-metre layer of clean soil. Despite gas pipes, percolator wells and ditches in some places bearing witness to the area's past as a waste tip, the extensive transformation of the island has opened up for many leisure activities and outdoor experiences. The area is now open to nature lovers, joggers, associations, institutions and anyone who wants the experience this special landscape close to Odense. The many activities that can be performed include Nordic walking, mountain biking, canoeing and kayaking. The long-term objective is for the area to provide facilities for both physical activity and reflection.


Master plans: Stockholm, Sweden


The extensive Stockholm Royal Seaport project is the latest attempt of the Swedish capital in pursuing its sustainable city dream. The ambitious goal is to create a district that can function as a model for other growing cities around the world. The area has been part industrial land and part Royal hunting grounds. The old industrial gasometers that have been the symbol of the area up until now will be transformed into apartments and a cultural centre, or torn down and re-erected.


The project envisions 10.000 new apartments and 30.000 new work places upon completion, as well as urban parks, an art gallery and a harbour for cruise ships. Some of the features include being fossil fuel free, made possible through initiatives such as energy efficient transportation, food waste becoming biogas as well as reuse and circulation of water, waste and energy within the district. Much effort is put into the most visible elements, such as planting oaks for biodiversity and creating spectacular green-design buildings.


Transportation: Vienna, Austria


In 2008, a 99 flats housing project called “Bike-City” got an unexpected huge positive feedback. The particularity of the project lies in the design of the development, which focuses on the needs of bicycle users. It includes a number of bike-friendly features such as a garage for repairs, plenty of safe cycle storage space, large elevators, etc. In addition, the premise was that money should be taken away from building one automobile parking space for each household and put into communal facilities that raise the standard of living. Therefore, only 50% of typically required parking facilities were constructed. The resulting high standard of living at an affordable cost made the project a big success and determined the city to plan for yet another bike-city project in Vienna.


Waste: Zurich, Switzerland


During the period 1992-2005, Zürich managed to reduce its municipal waste production by 28%. The Swiss city has pursued a radical waste policy which has turned its citizens into environment-aware recyclers and revolutionised their consumption habits. The change is the result of a collaborative effort between local and regional lawmakers, NGOs and Zürich's waste disposal authority. The solution consisted of the “Züri-Sack” and “Zürich recycling” and an extensive information campaign designed to motivate consumers to commit themselves to sustainable waste disposal and start composting.


Zürich householders were thus faced with the following choice: separate waste (by recycling at the various collection points made available and/or composting) or pay for the waste they sent to incineration through the “Züri-Sack”. Penalties amounted to as much as 250 Swiss francs, incentivising citizens to produce the least possible amount of waste. Having to pay for the volume of waste generated and being responsible for delivering packaging material to recycling stations also made people more aware of unnecessary packaging. Retailers now use much less packaging and offer customers the opportunity to unwrap their purchases and leave packaging behind.


Water: Berlin, Germany


The Urban Waterscape scheme that has been designed and implemented in the Potsdamer Platz in Berlin combines rainwater harvesting with a recreational cityscape and demonstrates how recycling rainwater can be of benefit to the cities of the future affected by climate change. The idea is that the rainwater should be used where it falls. About 60% of the roof space is covered with grass, so that some of the rainwater evaporates while the rest is stored.


A little more than half of the harvested rainwater is used for irrigation, the pools and canals in the area, while the rest is used in the buildings to flush lavatories and by fire extinguishing systems. Five massive underground cisterns accommodate the excess water in the event of extremely heavy rainfall. From here, the water is fed into the system of canals. Integrated into the system are biotopes, plants with a cleansing effect which filter the water as it passes through them. The falling rain becomes the water table and the canal installation in the open cityscape has helped to make the square one of Berlin's greatest tourist attractions.





The examples given above open a very positive perspective on the possibilities for sustainable development that cities everywhere could pursue. Of course, only contemplating these alternatives does not automatically imply that they can be implemented tomorrow. A variety of factors, starting with funding and up to consensus among responsible institutions, need to be favourable. However, local, regional and national authorities are beginning to recognize the need for an integrated, holistic approach in urban planning and sustainable solutions may well be fitted in this approach.


Fortunately, the number of cities adopting green practices has increased. Given the large efforts entailed by such initiatives, it is understandable that all of these cities are keen in showcasing their achievements and inspiring others to follow their lead. In fact, some cities came together to form groups and networks, where they can share ideas and collaborate. For instance, the Sustainable Cities International Network is comprised of 40 cities, towns and metropolitan regions around the globe that share the common goal of moving their communities to more sustainable futures. Acting as “urban laboratories”, Network cities adopt technological and social innovations and then adapt and implement them – making improvements to the innovation as they proceed. In turn, what they learn is shared with other members of the Network and not only.


New models of housing, energy and mobility are becoming available and exploring them can be a good response (if not the only one) to the challenges that lie ahead, such as a growing population and climate change. It is in the power of our leaders to start a dialogue and initiate such projects, but, most importantly, it is in our power to demand this from them.




sustainable_cities.txt · Last modified: 2012/10/10 20:37 (external edit)