Multi-functionality and multiple use: important features for sustainable cities

I want to write again on a topic that highly interests me. I wrote a blog ‘A sustainable city needs to be smart’ in May 2012. The topic I want to discuss this time builds on this subject.

I did some studies about making urban areas more sustainable during my work as a researcher at Wageningen University (The Netherlands). Together with a colleague with a background in spatial planning, I performed a study on the diversity of urban areas. We wrote a paper on the subject. We discussed the importance of a multi-functional urban area. It is important to see the chances the different urban functions have to offer in reaching a sustainable future.

In that way, having an industrial area in the vicinity of a residential area could be advantageous. Think about the concept of ‘Industrial Ecology’, with the case of Kalundborg in Denmark as example. Industrial Ecology can be seen as an example of park management: the companies within the borders of an industrial area try to find ways to re-use materials, to create new products from residual resources and to limit waste. A way of dealing with empty space in industrial areas and allowing other companies to build an industrial facility in that area, could be to use the local characteristics and available resources as restrictions. In that way, only a company that can be part of the chain is allowed to start its activities in the industrial area.

Park management is a good start, but it is not enough to make a complete urban area more sustainable. Therefore, we used the term ‘urban management’ (Leduc & Van Kann, 2013), in which we propose to broaden the scope and to look for options outside the borders of the industrial area. Often these industrial areas are close enough connected to residential areas or office space were, e.g., waste heat can be very useful, or residual resources from industry can be used to build houses, roads. Empty space in industrial areas can be used to collect water or to produce energy. It is very important to find synergy, so collecting water and energy can go together.

In order to create a sustainable urban area, we need to know how the area looks like. So, it is very important to perform a thorough check of the area first. Use this check to find out which functions are available in the area, at which locations, at what distances, what type of energy, materials and water is used and how much. Try to answer which type of energy, materials and water is needed at which quantity, at which location and when. An answer to these four questions can help to find better, more efficient ways to use energy and other resources, and to re-use resources.

The idea is to transform the urban area from a linear, resource-to-waste, metabolism to a more circular metabolism. In such a system resources can be used multiple times, more efficiently and effectively, and waste is not seen as waste, but as a residual resource. Any resource – energy, water, material – can be seen as a resource with still some remaining quality after use. When producing energy, lots of heat is produced that is mostly thrown away. This waste heat can also be seen as a residual resource that can be used by other urban functions for industrial processes or heating purposes. A similar idea can be found for water and materials: certain tasks in the household or industry need clean water, which after use will be ‘grey’ water and is usually eliminated via the sewer. If that ‘grey’ water is seen as a residual resource and not eliminated immediately, it can be used for other purposes like toilet flushing or gardening. An example for materials could be wood: it can be used immediately to be burned and produce energy, but it could be used more effectively. The wood could first be used to build a house, after the lifetime some of the beams could probably still be used to make furniture and in the last phase the wood could be used to produce energy. By following this chain, the same piece of wood would still produce the same amount of energy, but its qualities are used more effectively.

The ideas are based on research performed by the author and described in a published paper:

Wouter R.W.A. Leduc and Ferry M.G. Van Kann. Spatial planning based on urban energy harvesting toward productive urban regions. Journal of Cleaner Production, 2013, 39, pp. 180-190.

Available by author on request.

Wouter Leduc

By wouterleduc Posted in General

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