Q: How would you define a city? 

A: I would define a city similar to Wikipedia: “A city is a human settlement of a notable size. It is a permanent and densely settled place with administratively defined boundaries whose members work primarily on non-agricultural tasks. Cities generally have extensive systems for housing, transportation, sanitation, utilities, land use, production of goods, and communication. Their density facilitates interaction between people, government organisations, and businesses, sometimes benefiting different parties in the process, such as improving the efficiency of goods and services distribution”. I would add to this that cities are those ultra dynamic places that function as global leaders in a world increasingly dominated by city-states. The viability of cities determines the well-being of its inhabitants, the surrounding regions, and the nations in which they are located. 

Q: What is the 2000-Watt society about? 

A: Watts per person is an excellent measure of individual energy consumption. Since almost all human activities are energy-dependent, or can be expressed as energy, watts translate a wide variety of human activities into a precisely quantifiable unit that is comprehensive, easy to understand, and can be used as a general measure. Of course, we can use watts to measure our electricity and any other fuel use (coal, oil, natural gas, nuclear, etc.), the energy needed to produce buildings, roads and other infrastructure such as cement, steel, glass, chemicals, etc., often referred to as embedded energy. Watts also quantify the energy costs of mobility, communication, emissions, resource use such as water, air, minerals, etc. and the efficiency of markets. The solar radiation that hits the earth is also measured in watts. 

When we formulated the concept of the 2000-Watt Society in Switzerland in the mid-1990s, the average world energy consumption per capita was 2,000 watts, some countries far above that, such as the USA with around 12,000, Europe with 7,000, but other countries like China with 1,800 or Bangladesh with 500 watts. The 2000-Watt society for all humans is a fair concept, forcing energy wasters to drastically improve their energy efficiency and giving those below this limit the energy to develop. It is also a perfect concept to plan for the demand side, as opposed to the global effort to boost the supply side at almost any cost. 2,000 watts is equivalent to 17,500 kWh per year or the consumption of 1,700 liters of gasoline per year, all per person. 

The 2000-Watt Society concept is an excellent benchmark to quantify where we are on the path to a more sustainable world. It forces people to reduce emissions, conserve resources and increase energy efficiency. It is a driver for innovation, because highly energy-efficient technologies are needed by everyone. The concept comprises by definition scope 1 through 3. Though singling out the different scopes is possible, it was never part of the concept. At the beginning of the first decade of the second millennium, many cities in Europe began to adopt the concept of the 2000-Watt Society as a planning tool for the future of their cities. In a referendum held in 2008, the citizens of Zurich adopted the concept of the 2,000-Watt society as a guideline for the planning and future development of the city by a majority of 76 percent. Many cities in Europe, the USA, Australia and, more recently, India have followed suit, and discussions are underway in China. 

Nothing is completely ideal, including the concept of the 2000-Watt Society. This concept makes no distinction between fossil and renewable energy. As fossil fuels will still account for more than 60 per cent of the energy supply in 2050, the concept is still relevant. Based on the need to reduce emissions, the initiators postulated early on that around half of the 2,000 watts should ultimately come from renewable sources. This sets an achievable target for renewables to limit global emissions to a level of around 1.5 °C global warming. The 2,000-Watt society is silent when it comes to protecting health, the ecological balance and biodiversity itself. However, energy is needed to repair damage and protect deficits in these areas. 

Q: Do you think it needs to be adapted to different contexts, beyond how it was implemented in the Western context? 

A: The baselines of the 2000-Watt Society concept need no adaptation. The Watt is a physical quantity that is the same everywhere, probably in the entire universe. However, the way in which it is implemented will differ. What works for buildings in temperate zones certainly cannot be copied everywhere. Other solutions are required in the tropics. In addition, regional and local cultures and habits call for adapted or completely different realisations. For example, a long house in Kalimantan is conceptually completely different from a communal house somewhere in the West, heating or cooling require totally different approaches, particularly at high humidities, or roads in Scandinavia with frost and thaw have to be built differently from roads in areas with heavy monsoons and no frost. There are certainly many other examples. For me as an engineer, scientist or planner, these differences are a great opportunity. It's a wide open field to push boundaries. NUS Cities is an almost perfect place where adapted and new solutions can be developed or tested. 

Q: Why have you been interested in Singapore? 

A: Singapore is one of the most vibrant places in the world. It is the place where the East meets the West. The population is highly diverse and multicultural. Singapore is able to bring all these elements together to create something new, something exciting. Singapore is the place where the future of cities is being developed. The lack of space is forcing Singapore to find new solutions on how to make a city liveable for all citizens despite its high population density. Decision-making in Singapore is highly pragmatic and is not influenced by dogmatic views. Singapore is located in the tropics. The tropics are the part of the world where population growth and new urban development will be a challenge not only locally but for global communities as a whole. Singapore has the potential to serve as a beacon for the well-organised and innovative handling of future metropolitan areas. Singapore has excellent universities with many great researchers and personalities. Need more reasons? 

Q: What is the future of cities? 

A: As I said at the beginning, cities are the engine for the future of humanity, they are the leaders of the world. Cities are the places of innovation. Every city is a laboratory where new ways of living together can be tested. There is no one size fits all. Every city is different, has developed different solutions; some are better than others. We can only learn from this diversity, develop the best approaches and avoid the bad examples. The mediaeval proverb “city air makes you free” is becoming more and more true today. Cities offer work, security, services for individual well-being, intellectual challenges, etc. As humanity increasingly lives in cities, urban living will become the predominant way of life for humans on earth. 

As food production becomes more efficient, less land will be needed for agriculture. The rural population will move to the cities, reducing the population pressure on rural areas and creating space for recreation and nature. In rural areas, the gravity of cities can be a trigger for some ecosystems to recover and create space for increasing biodiversity - an almost counter-intuitive effect. As a consequence, cities have the potential to make the planet more sustainable despite demographic trends.