Finstral magazine F_04
Frame reframe: 180 pages of interviews, reflections and opinions on topics from the vast field of architecture.
Aluminium.
Circular thinking.
1. Production
Aluminium is derived from bauxite (primary aluminium) or by recycling aluminium waste (secondary aluminium). The usual method for this is fused-salt electrolysis using the Hall-Héroult process, which requires significant amounts of energy (13–15 MWh per tonne of aluminium). Processing aluminium waste is much more energy-efficient, requiring just 0.7 MWh per tonne – an energy saving of up to 95% compared to primary production.
2. Opportunities
Unlimited recycling: Aluminium can be recycled numerous times while still retaining the majority of its original properties, which makes it attractive for the circular economy.
Optimised carbon footprint through decision-making in materials and design: Modular design makes decomposition into pure components easier and reduces material consumption.
Carbon reduction through green energy: Recycled aluminium can reduce the carbon footprint to 3.3 kg CO2/kg. Primary aluminium with energy from coal-driven power stations, on the other hand, produces up to 20 kg CO2/kg. In regions that use a lot of renewable energy, such as Norway and Iceland, primary aluminium can be produced with a carbon footprint of 3.7 kg CO2/kg (e.g. ISAL billets) or just 1.9 kg CO2/kg in particularly optimised processes (e.g. Hydro 75R Green Billets).
Social sustainability: Increased recycling reduces dependence on bauxite mines in countries with problematic labour conditions, such as Brazil and China.
Green smelting process under development: The first pilot projects for hydrogen-based and biogas-based smelting processes indicate that we will be able to achieve almost emission-free aluminium production in the future.
Better material availability through closed circuits: Material banks and leasing models could ensure that aluminium is consistently fed back for recycling.
Increasing significance of environmental product declarations (EPDs): Environmental product declarations are increasingly becoming standard in the construction industry. Recycled aluminium improves ratings under LEED, BREEAM and WELL certification.
Aesthetic factor in window construction: Windows don’t necessarily need aluminium for their functioning and durability, so the kind of minor losses in material quality found in secondary aluminium are acceptable.
3. Challenges
Energy-intensive recycling process: Although aluminium can be recycled endlessly, processing post-consumer scrap requires complex sorting and smelting technologies, particularly if the material has been contaminated with lacquer or foreign substances.
Impurities and alloy problems: Undesirable alloys cannot always be removed. That means the proportion of recycled aluminium must be precisely calibrated to ensure its mechanical properties and workability. A high proportion of post-consumer scrap can negatively impact the material quality.
Slower processing: Post-consumer aluminium slows the extrusion process, which increases production costs.
Material imbalance and lack of regulation: Europe exports 1.2 million tonnes of aluminium scrap per year while simultaneously importing emission-intensive primary aluminium. The lack of carbon pricing keeps primary aluminium artificially cheap and impedes a sustainable circular economy.
Lack of recycling infrastructure: Europe needs more collection points, better scrap sorting and targeted funding programmes for aluminium recycling.
Electricity mix – a critical factor: In countries with carbon-intensive electricity such as Poland (600 g CO2/MWh), the carbon footprint remains high – even for recycled aluminium.
4. Best-case scenario 2050
Completely closed material circuit: Advanced recycling and sorting technologies make primary aluminium superfluous.
80–100% recycling rate: Aluminium production is almost carbon-free, with a footprint of less than 2 kg CO2/kg.
Green smelting process: The use of hydrogen and biogas as fuels further reduces emissions. Advanced electrical smelting ovens operated with renewable energies ensure even greater reduction of carbon emissions.
Material circuits and leasing models established: Instead of direct sales, aluminium products such as windows, façades and other construction elements are used under a leasing model. They are then returned under controlled conditions so they can be completely recycled and reused. Material banks manage these products throughout their entire lifecycle to ensure a closed circular economy.
Political regulation promotes the circular economy: Measures such as CBAM and similar mechanisms make sure that carbon-intensive aluminium imports attract higher import duties. In addition, subsidies for recycling plants and collection points promote a more efficient circular economy.
Reduced aluminium content in window profiles: New constructions use less aluminium – saving it for visible strips, for instance.
Aluminium is derived from bauxite (primary aluminium) or by recycling aluminium waste (secondary aluminium). The usual method for this is fused-salt electrolysis using the Hall-Héroult process, which requires significant amounts of energy (13–15 MWh per tonne of aluminium). Processing aluminium waste is much more energy-efficient, requiring just 0.7 MWh per tonne – an energy saving of up to 95% compared to primary production.
2. Opportunities
Unlimited recycling: Aluminium can be recycled numerous times while still retaining the majority of its original properties, which makes it attractive for the circular economy.
Optimised carbon footprint through decision-making in materials and design: Modular design makes decomposition into pure components easier and reduces material consumption.
Carbon reduction through green energy: Recycled aluminium can reduce the carbon footprint to 3.3 kg CO2/kg. Primary aluminium with energy from coal-driven power stations, on the other hand, produces up to 20 kg CO2/kg. In regions that use a lot of renewable energy, such as Norway and Iceland, primary aluminium can be produced with a carbon footprint of 3.7 kg CO2/kg (e.g. ISAL billets) or just 1.9 kg CO2/kg in particularly optimised processes (e.g. Hydro 75R Green Billets).
Social sustainability: Increased recycling reduces dependence on bauxite mines in countries with problematic labour conditions, such as Brazil and China.
Green smelting process under development: The first pilot projects for hydrogen-based and biogas-based smelting processes indicate that we will be able to achieve almost emission-free aluminium production in the future.
Better material availability through closed circuits: Material banks and leasing models could ensure that aluminium is consistently fed back for recycling.
Increasing significance of environmental product declarations (EPDs): Environmental product declarations are increasingly becoming standard in the construction industry. Recycled aluminium improves ratings under LEED, BREEAM and WELL certification.
Aesthetic factor in window construction: Windows don’t necessarily need aluminium for their functioning and durability, so the kind of minor losses in material quality found in secondary aluminium are acceptable.
3. Challenges
Energy-intensive recycling process: Although aluminium can be recycled endlessly, processing post-consumer scrap requires complex sorting and smelting technologies, particularly if the material has been contaminated with lacquer or foreign substances.
Impurities and alloy problems: Undesirable alloys cannot always be removed. That means the proportion of recycled aluminium must be precisely calibrated to ensure its mechanical properties and workability. A high proportion of post-consumer scrap can negatively impact the material quality.
Slower processing: Post-consumer aluminium slows the extrusion process, which increases production costs.
Material imbalance and lack of regulation: Europe exports 1.2 million tonnes of aluminium scrap per year while simultaneously importing emission-intensive primary aluminium. The lack of carbon pricing keeps primary aluminium artificially cheap and impedes a sustainable circular economy.
Lack of recycling infrastructure: Europe needs more collection points, better scrap sorting and targeted funding programmes for aluminium recycling.
Electricity mix – a critical factor: In countries with carbon-intensive electricity such as Poland (600 g CO2/MWh), the carbon footprint remains high – even for recycled aluminium.
4. Best-case scenario 2050
Completely closed material circuit: Advanced recycling and sorting technologies make primary aluminium superfluous.
80–100% recycling rate: Aluminium production is almost carbon-free, with a footprint of less than 2 kg CO2/kg.
Green smelting process: The use of hydrogen and biogas as fuels further reduces emissions. Advanced electrical smelting ovens operated with renewable energies ensure even greater reduction of carbon emissions.
Material circuits and leasing models established: Instead of direct sales, aluminium products such as windows, façades and other construction elements are used under a leasing model. They are then returned under controlled conditions so they can be completely recycled and reused. Material banks manage these products throughout their entire lifecycle to ensure a closed circular economy.
Political regulation promotes the circular economy: Measures such as CBAM and similar mechanisms make sure that carbon-intensive aluminium imports attract higher import duties. In addition, subsidies for recycling plants and collection points promote a more efficient circular economy.
Reduced aluminium content in window profiles: New constructions use less aluminium – saving it for visible strips, for instance.
Circular thinking.
Taking sustainability seriously means using materials in a way that prevents waste. That applies to window manufacturers, too. A circular dialogue with Finstral’s main suppliers.
