Cities should be resilient against climate change (adaptive) and utilise more useable residual materials as raw materials (circular). Wageningen Environmental Research (Alterra) offers a set of tools that helps city authorities meet these new demands.
Wim de Haas from Wageningen Environmental Research (Alterra) coordinated the ‘water, food and energy’ area of the Adaptive Circular Cities project. With a budget of 1.3 million euros, Wageningen University & Research partnered with knowledge institutes Deltares, TNO and ECN in concrete cases to help realise some ambitious urban goals. “For example, we developed a tool that allows cities to choose between the possible second lives of their organic waste streams,” says De Haas. This clearly goes beyond vegetable and fruit composting or fermenting organic waste into biogas. “Organic waste can be used to grow algae, or be fed to insects which can in turn provide protein. Technically speaking it is possible to use sewage sludge as a source of building blocks for bioplastics.”
Interface between circular and biobased
This new tool lies firmly in the interface between a more circular-oriented economy and the biobased economy. “There are major opportunities for cities to reduce dependency on fossil fuels and base their energy and raw material supplies more on renewable, vegetable raw materials.” Another tool is a new type of monitoring, which enables residents and government officials to work together at a neighbourhood level in the field of energy consumption and waste production.
Water management via green roofs
Water management is another way in which cities can make a difference, according to De Haas. “We developed a design tool that allows cities to see which type of green roof is best for which roofs in which neighbourhoods. The roof vegetation on these green roofs largely absorbs heavy showers, retaining water and keeping the sewers from overflowing.” Green roofs also provide insulation that reduces heating costs in winter and, by offering cooling, reduces the need for air conditioning on tropical summer days.
In addition to clear technical benefits, cities offer advantages that are less easily expressed in figures or funds. A climate robust circular city is a more attractive place for residents and companies. Moreover, the chances of people becoming ill due to heat stress in cities full of concrete or due to fine particles is thought to be reduced by the presence of plants and trees.
Cases in Duiven, Utrecht and Amsterdam
The design tools were tested in physical cases last year, including at the Jaarbeurs exhibition area in Utrecht, the Innofase industrial estate in Duiven, and the Buiksloterham neighbourhood of Amsterdam North.
Wim de Haas underlines that the design tools mainly provide insight into the technical possibilities of residential areas and industrial estates, but that many issues are of an administrative or legislative nature. “There are municipalities that only allow standard paving stones, and not porous ones, for instance. This is a shame as the latter allow water to enter the soil more easily and prevent it from entering the sewers. These obstructions should be removed if we are ever to achieve climate-adaptive, circular cities.”