Recycling instead of downcycling

Aluminium plays a key role in sustainable, future-proof construction. Thanks to its ability to be repeatedly recycled, this proven material saves valuable resources and reduces CO2 emissions. At the Innovationsbogen in Augsburg, designed by Hadi Teherani Architects, a façade made from WICONA’s 100% end-of-life aluminium has been implemented for the first time. The circular economy with aluminium is now a built reality.

 Energy balance of primary aluminium, Hydro CIRCAL 75R, Hydro CIRCAL 100R

According to information from the European Committee for Standardization on "Sustainability of construction works" (CEN/TC 350), 50% of the materials obtained from the earth are used for buildings. During their lifecycle, buildings are the largest energy consumers: they use almost half of primary energy and produce around 40% of all Europe’s greenhouse gas emissions. Waste originating from building materials account for 25% of the total waste generated annually. Given that the global population will probably increase markedly in the next few decades and around 70% of these people will live in cities and urban areas, we can expect a further rise in the consumption of raw materials and energy, as well as an increase in CO2 emissions from buildings in those cities. In view of this, aluminium as a key material in the building sector is of particular importance. Of the roughly 86 million tonnes of aluminium used worldwide in 2021, 25% was reported as being used by the building sector. Treating limited resources responsibly is therefore more important than ever, and is a key factor in environment- and climate-friendly construction.

Recycling plays a central role, and for a good reason, because aluminium is one of the few materials that retains its characteristics and quality to the full after reprocessing. Another significant benefit is that recycling aluminium only uses around 5% of the energy that is consumed in manufacturing primary aluminium. The aim must therefore be to significantly increase the use of secondary aluminium (end-of-life aluminium). Primary aluminium currently accounts for around 75% of global production – in other words, material that is produced from bauxite in a costly and energy-intensive process.

Co₂ footprint: Cut-off methods

Pre- and post-consumer scrap

In this context it is important to note that not all recycled aluminium is the same. There are fundamentally two different sources of material for the metal recycling process – and these have a decisive influence on the energy balance or CO2 footprint of the recycled material. The first source is what is referred to as pre-consumer scrap – in other words, process scrap aluminium. This material has never been used as a product and comes from production waste or processing steps such as extrusion. It is collected from the production process and then made into a product. The second and less common option is post-consumer scrap or end-of-life aluminium (EoL). This is the name given to material that has already been used in a product and has passed through its whole lifecycle. End-of-life aluminium, as used by WICONA, comes from sources such as façades, windows and other construction elements that have been disassembled and recycled. In the past the recycling process often converted

this aluminium into inferior alloys.

From a present-day understanding this would be called downcycling, as these alloys cannot be used to make high-quality aluminium profiles for the construction industry. As a pioneer in the field, Hydro developed a sorting and classification process that enables large quantities of end-of-life aluminium to be sorted in a way that means they can be processed into high-quality aluminium profiles. These alloys are then called Hydro CIRCAL 75R or Hydro CIRCAL 100R, depending on the recycled proportion.

Co₂ footprint: Avoided burden method

Calculating the CO2 footprint

Irrespective of whether it is pre- or post-consumer scrap, when evaluating the material for a life cycle assessment the CO2 footprint is a key parameter. It is generally acknowledged that post-consumer scrap has a zero CO2 footprint due to its previous use in a product. For pre-consumer scrap, however, the current standards for life cycle assessments enable two different calculation methods that have a significant influence on the environmental assessment of the material. In what is known as the cut-off method, the footprint follows the products. This means, for example, that for extrusion billets with a CO2 footprint of 1,000 kg, the extruded profiles bear the whole carbon emission, while the process waste – which usually amount to 20% – are not assigned any CO2 footprint. As the entire CO2 footprint is assigned to the original product, it follows that pre-consumer scrap of all sources is considered as being decarbonised and there is no distinction made between this and post-consumer scrap, which considerably weakens a transparent CO2 assessment.

As a result, the first process cycle gives rise to a product made of aluminium with a significantly increased CO2 rucksack, which is processed into applications where the topic of sustainability is not given any special attention. The 20% process scrap produced from this is decarbonised "on paper" and, in a further melting and extruding process, can be made into a product with a low CO2 footprint. Using this principally unsustainable method gives no incentive for process improvements.

Post-consumer scrap (end-of-life aluminium) processing takes place in the Hydro plant in Dormagen and is monitored by an independent third party

The avoided burden method is significantly more transparent – in relation to the aluminium sector – and is also that used by WICONA for life cycle assessment calculations. In this method the CO2 footprint follows the material. This means that, in the case of the above-mentioned extrusion billets with a CO2 footprint of 1,000 kg, the environmental impact is split between the original product and the scrap material based on the physical distribution – i.e. 800 kg CO2 is allocated to the profiles and 200 kg CO2 to the process scrap. Consequently, the pre-consumer scrap arising from the process is allocated the CO2 footprint of its original material. A further reduction of the CO2 emissions can only be achieved through costly optimisations in the process steps. WICONA believes that this is therefore the only correct method for a truly sustainable circular economy.

The façade units in the Innovationsbogen are manufactured and installed by Schindler Fenster + Fassaden (Roding).

External certification along the value chain

When evaluating the CO2 footprint of aluminium, it is important to consider whether the declared values apply to the whole value chain (cradle to grave) or only parts of it (cradle to gate with options). This is specified in the life cycle assessment and in the resulting Environmental Product Declaration (EPD), because a cradle to grave evaluation is only an optional requirement. In addition, external certifications – for example through the Aluminium Steward Initiative (ASI) – can increase credibility. ASI is the most internationally recognised standard relating to environmental, social and governance (ESG) aspects of the entire aluminium value chain. The evaluation is based on the sustainable production of aluminium from bauxite mining to product manufacture and takes account of recycling of pre- and post-consumer scrap. Hydro was one of the first companies to obtain ASI certification. The entire value chain of WICONA aluminium is also ASI certified.

The "Innovationsbogen Augsburg" (Hadi Teherani Architects) is the first project in the world with a WICONA façade solution made from 100% end-of-life aluminium.

Complex recycling process

Det är uppenbart att mängden uttjänt aluminium för närvarande fortfarande ligger långt under mängden primäraluminium och processmaterial. Den nuvarande utvecklingen av hållbarhet inom byggsektorn säkerställer dock en betydande ökning (för ytterligare information se https://aluminium-stewardship.org). För att kunna återvinna de ökande mängderna aluminium i tillräckligt hög kvalitet i framtiden krävs segregerad insamling och bearbetning. Uttjänt aluminium- till exempel när det tidigare använts i ett fönster - har vanligtvis anodiserats eller belagts och profilerna kan också innehålla andra komponenter som till exempel en termisk brytare. Återvinning kräver därför omfattande kunskap och den senaste tekniken och processtegen (som i Hydros egen återvinningsanläggning i Dormagen): från den första inspektionen via fragmentering, separering, krossning och sortering hela vägen till smältning. Slutligen förbereds materialet på ett sådant sätt att det, i rätt legering, kan återföras till produktionen av högkvalitativa aluminiumprofiler. Detta är målet för AIUIF e. V., där WICONA är medlem. Hela processen på Hydro övervakas och certifieras löpande av det oberoende testorganet DNV-GL.

True circular economy with end-of-life aluminium

In order to respond actively to the increasing requirements of climate protection, Hydro Building Systems with its WICONA brand has launched the "Build Beyond Tomorrow" strategy for the future – in part to advance the development of sustainable products. With Hydro CIRCAL 75R, the company has been offering an aluminium alloy that consists of at least 75% end-of-life aluminium since 2019 and, with 2.3 kg CO2 per kg aluminium, possesses one of the lowest CO2 footprints worldwide. This is 65% less than the European average (around 6.8 kg CO2). All new system solutions contain at least 75% recycled material and 95% recyclable material.

In addition, recycled polyamide is used for the insulating strips, and all other materials – besides aluminium also TPE, Zamak, stainless steel and ABS – are in line with the 75/95 premise. The next step towards a true circular economy was the market launch in spring 2023 of Hydro CIRCAL 100R – the world's first aluminium alloy made from 100% recycled end-of-life aluminium. This material has the lowest CO2 footprint at international level with an average of 0.5 kg CO2 per kg aluminium.

Innovationsbogen Augsburg

The Innovationsbogen Augsburg has the first façade to be made from 100% end-of-life aluminium. The building designed by Hadi Teherani Architects (Hamburg) is to be awarded a uLEED platinum sustainability certification. The 145-metre-long arc-shaped building is located at the southern entrance to the new innovation park where it rises from its surroundings of a flowering meadow. The main "sustainability" guiding principle is visible in such features as its harmonious integration in the environment and a maximum flexibility in the ground plan design. This permits both traditional cubicle offices as well as open-plan areas, depending on requirements.

A further fundamental element is the energy concept, which includes photovoltaic systems, heating and cooling sails for the building's climate control and a district heating supply. An important contribution to sustainability is also provided by the façade. This entails a special design of WICONA’s WICTEC EL evo unitised façade, which makes the first ever use of the aluminium alloy Hydro CIRCAL 100R, made from 100% end-of-life aluminium. With the 85 tonnes of Hydro CIRCAL 100R installed, this corresponds to a CO2 reduction of 527 tonnes.

Holistic thinking about the circular economy

In summary it can be stated that, in terms of climate protection and reducing CO2 emissions, all the partners in the construction sector should have the aim of using systems with a high proportion of post-consumer scrap (end-of-life aluminium) for the design and implementation of aluminium windows, doors and façades. In view of this, WICONA provides designers and clients with dynamic EPDs with which to compare a wide range of options and so calculate a precise CO2 footprint customised for each project.

In addition, the aluminium systems house supplier already offers solutions containing 100% end-of-life aluminium. What is required is the further development of a comprehensive recycling concept for windows and façades – based on the "75/95" concept already introduced to the market. This means including glazing, hardware and sealing systems in the collection and recycling processes. Practical cooperation is already available for this – for example with the glass industry and sealing system manufacturers. The goal is to be able to recycle a façade in its entirety.

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Over the last few decades the brand name of WICONA has developed into a synonym for aluminium profile systems that meet the highest standards. The high technological standards, rigorous system considerations and quality processing of the products, as well as comprehensive services and consultation, all make a significant contribution to the success of the brand. WICONA belongs to the Norwegian company Hydro, a fully integrated aluminium company with 35,000 employees in 40 countries on all continents, combining local expertise, worldwide reach and unmatched capabilities in R&D.

>> www.wicona.lt

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