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Downcycling, or cascading, is the recycling of waste where the recycled material is of lower quality and functionality than the original material. Often, this is due to the accumulation of tramp elements in secondary metals, which may exclude the latter from high-quality applications. For example, steel scrap from end-of-life vehicles is often contaminated with copper from wires and tin from coating. This contaminated scrap yields a secondary steel that does not meet the specifications for automotive steel and therefore, it is mostly applied in the construction sector.
Origin and effect
Downcycling can help to keep materials in use, reduce consumption of raw materials, and avoid the energy usage, greenhouse gas emissions, air pollution, and water pollution of primary production and resource extraction.
thumb|Downcycling of steel from scrap cars into buildings. Vehicle steel scrap, which is contaminated with other metals, is often remelted into construction steel that can contain up to 0.4% of copper. <blockquote> We talked about the impending EU Demolition Waste Streams directive. "Recycling, he said, "I call it downcycling. They smash [[bricks, they smash everything. What we need is upcycling where old products are given more value not less." He despairs of the German situation and recalls the supply of a large quantity of reclaimed woodblock from an English supplier for a contract in Nuremberg while just down the road a load of similar blocks was scrapped. It was a pinky looking aggregate with pieces of handmade brick, old tiles and discernible parts of useful old items mixed with crushed concrete. Is this the future for Europe?
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The term downcycling was also used by William McDonough and Michael Braungart in their 2002 book Cradle to Cradle: Remaking the Way We Make Things.
A detailed discussion on the relation between downcycling, open loop recycling and their environmental impact is provided by Geyer et al. (2015). They write that "Poor product design and EOL management can lead to recycled materials of poor quality, which, in turn, limits the applications these materials can be used in." They also argue that "closed-loop recycling neither intrinsically displaces more primary material owing to multiple loops (quantity argument) nor per se generates higher environmental benefits on a unit basis (quality argument)." The reason for their argument lies in the necessity to include the product system of the target application, in which the recycled material is used or not, into the assessment of overall primary material demand and environmental impact.