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City of the Sun: illuminating sustainable cities


  • Experts interviews

Architect Ashok Bhalotra developed a concept for a truly sustainable city. Through his perseverance, this idea has been realised in the form of Heerhugowaard’s City of the Sun.

Ashok Bhalotra is the chief executive officer of KuiperCompagnons, a Dutch-based specialist in architecture and urban planning. He is the initiator of the City of the Sun project in Heerhugowaard, the Netherlands, which is the largest CO2-neutral residential area in the world. This project began in 1993 and was completed in 2006. Built on a vacant site, the City of the Sun generates 10 MW of energy from wind and solar power, and uses natural water-filtration systems.

From where did the concept for the City of the Sun come?

While studying in Paris in the 1960s, I designed a conceptual university in my home town of Delhi for a competition. Focusing on the issue of self-sufficiency, I designed a rainwater-collection system to store water from the monsoon underground. This project opened my eyes to the importance of designing self-sufficient and sustainable urban settings. In many ways, it shaped my outlook as an architect.

Through the City of the Sun you aimed to inspire people to make small changes to help save energy. How do you encourage people to make such changes?

I think it is important that people see energy-efficiency measures as desirable. If you make such sustainability measures things to be proud of, people are going to work harder to have them in their communities. The same goes for sustainable public spaces, if people have a certain level of civic pride they will do more to protect their local environment.

Was it difficult to find political or financial support for the project?

The key to finding support was perseverance and the willingness to build bridges between the developers, the politicians and the inhabitants of Heerhugowaard. By having enough energy and by being consistent in how we presented our ideas for the sustainable city, we were able to convince others to support us. We received financial support not only from the Dutch government, but also from the province of North Holland and the European Union. In particular, the province and the EU consistently provided significant funding and, in many ways, were the mother and father of this project. The European Funding for the project was provided under the Commission’s Fifth Framework Programme.

A key feature of the project is its water system. What eco-innovations are used in this system?

Our natural biological water-filtration system, based on rainwater collection and reed-bed filtration, led to a major improvement in the water quality of the area. In addition to storing large amounts of water in both shallow- and deep-well systems, we have been able to meet the Dutch standard for swimming water.

What concepts, or specific eco-innovations, do you think could be applied in other cities?

There are a number of low- and high-tech solutions which could be adopted elsewhere. We have begun to take the ideas developed in the City of the Sun and use them elsewhere. For example, we are coordinating projects in Rajasthan, India and in Shenzhen, China using the same water-purification, solar and wind techniques. I believe it is not only important to share good ideas, but also to be constantly looking for new ideas. For example, the developer Dutchrainmaker came up with a wind turbine which can collect water vapour from the air for use as drinking water or in irrigation. It is important to share such knowledge. In terms of planning, the City of the Sun was intentionally orientated towards the sun with a north-south orientation that optimises the potential for solar energy. By thinking sustainably in the planning stage, we can improve the efficiency of a city.

It’s important to show that these concepts work. In Heerhugowaard, approximately 1 500 newly built houses are equipped with solar panels and heat pumps. Furthermore, there are currently three wind turbines. Combined, this gives us 10 MW of energy transformed into electricity, enough for 4 000 dwellings in the city. By showing others that sustainable cities are positive environments for future generations, we can encourage the adoption of similar measures elsewhere.

The City of the Sun, Heerhugowaard

  • Measures approximately 118 ha, including a 49-ha square island situated on a polder in the middle of a 60-ha lake.
  • A fully functioning city with all necessary amenities
  • 2 950 houses have been built
  • 3.75 MW is provided by solar panels located on the city’s buildings
  • Located in Park van Luna, there are 177 ha of recreational areas, including 75 ha of water for swimming.

More information:

Wijkpanel – Stad van de Zon:

Heerhugowaard – Stad van kansen: