Research Essay



“The way of life in cities of the developed world is characterized by high levels of consumption of resources and of the production of waste and pollution.” (Frey 2007, p87) This high level of consumption leads to the exhaustion of the planets resources. The Club of Rome concluded in 1972 in the report The Limits to Growth that: ”if the present growth trends in world population, industrialization, pollution, food production, and resource depletion continue unchanged, the limits to growth on this planet will be reached sometime within the next one hundred years .” (Frey 2007, p5) The production of waste in 2007 in The Netherlands was 60.422 million kg. Wherefrom 23.140 million kg comes from the building sector. (SenterNovem 2009)
As the natural resources in the earth become more valuable it is important to be cautious how we use them. As the building sector produces more than 1/3 of the waste, is there a lot that can be done to be more cautious with the natural resources and reduce the production of waste.

There are several ways how to reduce the impact of consumption and construction. On the one hand should the waste that is generated be reduced, reused or recycled and thereby extending the lifecycle of buildings, components and materials. Variations on those techniques are the concepts of Superuse and Cradle to Cradle. On the other hand should the impact of using new materials be decreased. So when new materials are used they should be (rapidly) renewable so that exhaustion of resources will be prevented. The question is how those concepts/techniques can benefit to the process of building, using and demolishing of settlements. And thereby reduce the amount of raw materials used and amount of waste generated. Ideally constructing with renewable resources and/or waste without producing waste during construction and demolishing.

What waste?
Bouwafval.jpgThere are three major producers of waste. The biggest one is the construction/demolition sector which produces 38% of all waste in the Netherlands. The second largest producer of waste is the industry with 28%. And with 16% are the households consumers the third biggest waste producer.
Households produce different kinds of waste. The table shows the different wastes that get collected separate per inhabitant per year. (Brauw, p XVI) The residual waste mainly consists of organic (33%), paper/cardboard (27%) and plastic (20%) waste. Especially the amount of plastic waste has grown over the last years.
Construction and demolition waste generally consists of debris, wood, wallpaper, floorings, window frames, doors and windows, roof tiles, sanitary elements, etc. The image shows what most construction and demolition waste consist of.
243 kg
Residual waste
79 kg
Kitchen and garden waste
66 kg
Paper and cardboard
44 kg
Heavy/big waste
21 kg
Glass
109 kg
Others

Processing waste.

Collection
As mentioned above, there are different kinds of waste produced by consumers. Besides the mentioned domestic waste is there also waste water coming from houses. This waste water gets collected in a septic tank. In this septic tank the waste water and sludge are separated.
The organic waste from a household gets generally separately collected by the consumers and picked up by the municipality. The municipality than transport it to a collection centre. Papers, glass and plastics gets generally separated by the consumers and collected by the municipality. Residual waste is collected by the municipality and separated for recycling.
The other domestic wastes get partly separated and brought to a municipal collection centre by the consumers. CityScheme2.jpg
Construction and demolition waste generally gets separated on the building site where different containers collect different wastes.
For high quality of reuse and recycling is it important that the collected wastes are carefully separated. As the purity of the collected materials determine the quality of the processed outcome. With reuse in mind components should be carefully collected to keep them in good condition. This will reduce the amount of work of improving or repairing the component.

Processing
To make the waste useful again it can be processed on different ways.
Waste water can be treated in a constructed wetland which will filter the water. The sludge from the septic tank can be processed with pyrolysis. Pyrolysis is the chemical demcomposition of condensed substances by heating, that occurs at high temperatures. Also the organic waste can be processed with pyrolysis.
The other domestic waste and the construction/demolition waste can be processed in different ways. The best way is reusing. Reusing is nowadays a normal part of life. Bottles get collected by the supermarket and refilled in a factory. In the building sector is reusing not yet far developed and mostly are new components and materials used for new buildings. Part of the reusing process is modifying the product to a state that it can be sold again, for example by cleaning, painting, fixing the product. Reuse can happen on different levels, urban, building, component and material level. Reusing at a bigger scale is generally better than on the lower scale. For example it is better to reuse a door than to reuse the wood of the door.
Another way of using waste is the ‘Superuse’ way. Superuse is a concept/technique developed by 2012 architects. The main idea of Superuse is using waste into new building components and thereby shortcutting the flow of products and elements. Superuse may appear similar to reuse, but there are some differences. Where reuse is based on using a component or material for the purpose what it is designed for. Superuse takes materials and components out of their designed purpose and use it in a different way. For example: reuse would use a used door again as a door, but with Superuse the door would be reused as a façade element.
If reuse or Superuse is not possible, the next best process would be recycling. Recycling is the process of converting wastes to raw material that can be reused to produce new products. The recycling process generally consist of melting or crushing the waste, wherefrom it can be used as a technical nutrient for new products.

Outcome
The different outcomes of waste processing are, generally, new materials, components, resources or nutrients. The waste water that has been treated in a constructed wetland has become clean water which can be used to recharge the watertable or brought back in the cycle of domestic water supply.
The outcome of the pyrolysis process consist of two products. On the one hand does it create bio energy, which can be used either for the pyrolysis of new waste or used for example as energy for heating a house. On the other hand produces pyrolysis the product Biochar. Biochar is a product that can be used to fertilize the soil. An extra advantage of Biochar is that it captures and stores carbon.
Out of the processing of domestic waste and construction/demolition waste can come a large variety of products. When components or materials are being reused the outcome is the same product as came in as waste. The reusable product gets sold as new products or as reuse products. For example the reused bottle gets sold as new in a supermarket and on the other hand are there also the so called recycle or second hand shops where the products get sold.
Superuse has been developed as a strategy for using waste into new buildings, but this technique can be used also on other ways. The outcome of the superuse process are new building materials, for example kitchen sinks or cable reels as façade element or bottles as bricks. The other ways of using superuse can be done in for example making art, toys, household items, etc. For example scrap metalCityConcept.jpg becoming a statue or a toy car made of tin cans or use cans to store nails.
The outcome of recycling are generally melted products or aggregate . Melted products are for example glass or steel which get modified into new products like bottles and windows or structural beams or cans. The aggregate comes generally from bricks, rubble, etc. This aggregate gets used in new materials like bricks or concrete.

Additional materials
Although a lot of materials can get out of waste, there will be always the need of new materials. Those materials and components should be selected and designed in such a way that exhaustion of resources and the production of waste is prevented.
Preventing exhaustion can be reached by using materials that are renewable. Examples of renewable materials are wood, straw, willow, clay, etc. Because the consumption of materials is very high and some renewable materials still take many years to renew, is it even better to use rapidly renewable materials. Examples of rapidly renewable materials are straw, wool, bamboo, etc. Those materials have harvest cycles of less than ten years.
When selecting and designing materials and components the concept of Cradle to Cradle can contribute to preventing exhaustion of resources and the production of waste. The main idea of Cradle to Cradle is that: “Products should be designed from the outset so that, after their useful lives, they will provide nourishment for something new. They can be conceived as “biological nutrients”. Or they can be “technical nutrients”. (McDonough, p..) The technical nutrients prevent the use of new nutrients, because they can be recycled. The biological nutrients can be used as fertilizer for the production of new renewable materials.

Demountability.
To enhance to possibilities of reuse, superuse and recycling are there some considerations for the design what has to be acknowledged. An important issue for reuse, superuse and recycle is the possibility to separate materials. To make this possible buildings, building components and materials have to be flexible and easy demountable. De ability to demount a building easy makesUrbanPlanFlows.jpg it easy to replace components of a building, which extends the buildings lifecycle. Easy demountable buildings and components also make it easy to use those components and materials for new construction, extending the lifecycle of the components and materials. If buildings, components and materials are easy demountable will separation be more easy resulting in higher quality of recycled materials.

Conclusion.
The processing of waste can become a economy for the settlement. The waste, from external construction and demolition sites, from external industries and the city’s consumer waste, starts with being collected at a point where it gets separated into different materials and in the different processes of reuse, superuse and recycle. Every process will have its own location close to the collection point to minimize transport. Close to those processing points will come the functions like shops and galleries where the public can buy or watch the products than have been processed out of waste.
The products coming from the waste processing and the use of new renewable materials can make the city like a growing organism. It feeds itself with waste and renewable materials wherefrom new buildings can be build.
Demountability will reduce the generation of waste from demolition. The city, buildings and component can be demounted and after that used at another place in another project. This makes that the city not only grows, but also can transform.




Renewable materials


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Cradle to Cradle


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Reuse


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Superuse


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Recycling


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