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Aluminium can be remelted and used again and again in new products, making it an environmentally friendly metal and sustainable building material
Pre-consumer versus post- consumer scrap Firstly, ‘recycled content’ covers both the pre-consumer and post-consumer waste within the product. One source is aluminium process scrap. This is waste produced from manufacturing processes, such as extrusion, where the metal has not yet been made into a consumer product. It may have been anodised or painted, but it hasn’t actually been ‘used,’ so is ‘pre-consumer.’ It is collected from the production process, returned to recycling plants, and then melted again to create something new. This is a positive, considering that when we recycle aluminium, we save about 95% of the energy used in the production of primary aluminium.
Post-consumer aluminium scrap is metal that has gone through its full life cycle and is ready for disposal, recycling or reuse. An aluminium window frame in a building, for instance, can be considered post-consumer scrap when the building is demolished and the aluminium is obtained and sent on to be remelted, then applied in a new product.
Differences in footprint The higher the post-consumer recycled content, the lower the carbon footprint. It is more difficult to produce top-quality metal that has a high content of post-consumer scrap. However, it yields a lower carbon footprint, so is therefore more appealing from a sustainability perspective. Going back to the window frame – an aluminium frame has probably been anodized and painted. It may also contain a thermal break – ie. the insulation within the frame. Conversely, process scrap is basically ‘clean’ metal.
Recycling the aluminium from a window frame is a complex process, with many steps; namely inspection, separations, shredding, and de-coating. The metal also needs to be x-rayed (to determine alloying elements), and then segregated – as different types of alloys should not be melted together if you want to obtain a similar quality of alloy back from the recycling loop.
A post-consumer rescue mission In a move that prevents this aluminium waste going to landfill, Technal parent company Norsk Hydro has created a range of aluminium products made with
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recycled, post-consumer aluminium scrap, such as facades and windows that have been dismounted from buildings and fully recycled.
The range includes products with at least 75% recycled aluminium from post- consumer scrap – featuring material with one of the smallest CO2 sector – 2.3 kg CO2
footprints in the emissions per kilo of
aluminium. This is seven times less than the global average for primary extraction. The company is working to launch new products with an even higher content of recycled aluminium in the future, with two projects in Europe due to feature aluminium that contains 100% recycled post-consumer material. This will lower the CO2
emissions per kilo of aluminium to just 0.5.
When specifying aluminium curtain walling, windows, doors and sliding systems in a credible sustainable way, a good starting point is checking the aluminium product process is fully traceable, and that an independent third party, such as DNV- GL, certifies the product. Systems may also have passed other certifications such as the ift Rosenheim, an EPD (Environmental Product Declaration) or the international Cradle to Cradle certification. In addition, there are aluminium system products on the UK market that meet standard green building certifications such as LEED, BREEAM and DGNB.
How to raise recycled aluminium content If your next build has a requirement for a sustainable aluminium system package, making sure to specify that the system uses recycled material in the tender document will provide clear direction for your supply chain. For example, this would mean aluminium with material usage of at least 75% end-of-life (EoL), e.g. EN AW-6060 T66. For aluminium with EoL recovery, material that has already been installed in and removed from a building is recycled once again.
The minimum 75% proportion of this post-consumer material (≥ 75% EoL material) must be verified by means of independent certification. To avoid misleading customers, a manufacturer marketing higher than average recycled content of above 90% in their products should disclose what fractions of post and pre-consumer scrap are included.
Gareth Evans is specification sales manager at Technal UK
ADF OCTOBER 2023
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