Knowing ‘what’ you’re specifying when it comes to recycled aluminium curtain wall, window and door systems could really make a difference to the carbon footprint on your next sustainable architecture project.

When designing buildings with circularity in mind, choosing aluminium is a no-brainer. It is one of few building materials that keeps its properties after recycling. It can be remelted and used again and again in new products, making it a sustainable building material.

Why it’s important to check how the aluminium is manufactured

However, at face value, compared with other building materials, the carbon footprint of primary aluminium can appear high if architects are looking at CO2 emission averages or the embodied carbon in building materials using tools like these. This is down to the way it is produced. If it’s produced sustainably, it in fact has one of the lowest carbon footprints.

A great start is to avoid aluminium where the fuel used to create the electricity for the smelting process results in a high carbon footprint. The world average, according to CRU, Hydro Analysis, IAI, is 16.7 kg of CO2 per kilo of aluminium, which is largely due to coal so looking for alternatives that use renewable energy from water (hydro power), wind and solar sources is one option.

Alternatively, look for aluminium that uses post consumer recycled aluminium in the production process, which means that a lower amount of heat (and therefore energy) is generated. According to European Aluminium (2015) in its “Recycling Aluminium. A Pathway to Sustainable Economy” document, only 5% of the energy required in the production of the primary metal is needed in the recycling process.

Some architectural aluminium systems therefore, are definitely greener than others and manufacturer claims that they are made from recycled content isn’t enough – it’s important to take it that step further and get to know the difference between subtler terms like pre consumer scrap and post consumer scrap as there is, in truth, a big difference.

Whether you’re specifying for a unitised, stick or bespoke façade solution, here are some useful definitions to help navigate the terms associated with recycled aluminium content:

Recycled content

In the context of the aluminium industry, recycled content includes both the pre-consumer scrap and post-consumer scrap in the product.

Pre consumer scrap – unused waste

Recycled pre-consumer or aluminium process scrap is, essentially, waste from a manufacturing process like aluminium extrusion – it has never been a ‘product’ as such.

A positive step in that when aluminium is recycled, it saves about 95 percent of the energy used in the production of primary aluminium.

Recycled post-consumer scrap - end-of-life or reclaimed aluminium

This is when an actual aluminium product has gone through its full life cycle and is ready for disposal, recycling or reuse, it is known as post-consumer aluminium scrap. An aluminium window frame in a building, for instance, can be considered post-consumer scrap when the building is demolished. The aluminium obtained would be sorted, remelted and then used to create a new product.

What’s the real difference?

Recycled and recyclable content = Better for the circular economy

Producing top-quality metal that has a high content of post-consumer scrap is a more complex process. However, it yields a lower carbon footprint so is therefore more appealing from a sustainable building perspective.

Looking at the aluminium window frame example again. An aluminium frame has probably been anodized and painted. It may also contain fasteners, screws, glass, thermal break – the insulation within the frame. Conversely, process scrap is basically ’clean’ metal.

Recycling the aluminium from a window frame has many steps including inspection, sorting, shredding, decoating. The metal needs to be x-rayed to identify alloying elements and segregated, as different types of alloys should not be melted together if you want to have similar high-quality alloy back from the recycling loop.

Stopping this aluminium waste going to landfill, WICONA parent company Hydro has created Hydro CIRCAL - a range of aluminium products made with recycled, post-consumer aluminium scrap, like façades and windows that have been dismounted from buildings and fully recycled.

Currently Hydro offers Hydro CIRCAL® 75R, with at least 75% aluminium from post-consumer scrap - one of the smallest CO2 footprints worldwide: at 2.3kg of CO2 emissions per kilo of aluminium. This is 6 times less than the global average for primary extraction.

The company is working to launch new products with even higher content of recycled aluminium in the future.

It’s worth noting that a producer marketing high average recycled content of above 90 per cent in their products should disclose what fractions of post and pre-consumer scrap are included.

To meet the growing demand for more sustainable products on building projects, WICONA offers windows, doors and facades produced with Hydro CIRCAL® 75R – a high quality recycled aluminium or Hydro REDUXA - a certified low-carbon aluminium.

By specifying Hydro CIRCAL or Hydro REDUXA, your designs will already be meeting standards-including green building certifications such as LEED, BREEAM and DGNB.

Sustainability credibility checklist for specifying aluminium curtain walling, windows and doors

Investigate traceability

Is the aluminium production process fully traceable? Does an independent third party, such as DNV-GL, certify the product?

Seek out certification proof

Look for systems that may also have passed other certifications such as the ift Rosenheim, an EPD (Environmental Product Declaration) or the international Cradle to Cradle™ certification.

Look for products that meet green building standards

There are aluminium system products on the market that meet standard green building certifications such as LEED, BREEAM and DGNB.

How to introduce higher recycled aluminium content in to your next project

Increasingly, clients are stating a sustainable aluminium system package as a requirement. For specification purposes, including the text below in the tender document will provide clear direction for your supply chain:

The system makes use of recycled material in the following area:

• 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 more.

The minimum 75 percent proportion of this post-consumer material (≥ 75% EoL material) must be verified by means of independent certification.



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