Aluminum is Forever
How this versatile, durable building material is shaping a sustainable future.
The following article is presented as part of a promotional partnership with Hunter Douglas Architectural. For those further interested in how recycled aluminum products can play into a sustainable architecture and design strategy, follow @MetropolisMag on Twitter for a live discussion titled #AluminumToday on May 18th, 1pm EST.
For architects and those who appreciate architecture, a visit to Rome is a life’s goal. With classics like the Colosseum, the Pantheon, and the Castel Sant’Angelo dotting the city’s map, visitors can experience some of architecture’s finest examples.
Another structure in Rome may not appear on many “must see” lists, but the San Gioacchino ai Prati Castello, a basilical Catholic church on the outskirts of Rome, nevertheless marks an important milestone in architectural history.
Built in 1898, the San Gioacchino features an eclectic mix of neoclassical and gothic architecture with impressive features like a two-story entrance facade and an ornate interior. But the key architectural element of the San Gioacchino is its aluminum-clad, octagonal dome, considered to be the first major application of the metal in architecture. Though it would take another half century for the material to gain widespread use in civil projects, the San Gioacchino and its cupola presciently demonstrated the flexibility and durability of this ever-adaptable material.
Today, aluminum is more important than ever as designers take serious note of the scarcity of natural resources and greenhouse gas emissions from industrial activity. And while the benefits of this metal are many—from its abundance, to its versatility, to its durability—it is the high degree of recyclability which makes aluminum one of the premier building materials for sustainable architecture.
A Heritage of Sustainability
For Hunter Douglas—a global architectural products manufacturer—aluminum holds the key to meeting sustainability goals and to reducing the company’s carbon footprint. The firm’s heritage in recycling aluminum dates back to 1946, when, as Europe recovered from the ravages of World War II, the Netherlands-based manufacturer pioneered technology for the continuous casting of recycled, lightweight aluminum. This advance eventually lead to the creation of metal Venetian Blinds (gaining the company worldwide renown) and with continued commitment to innovation and recycling, in the 1960s Hunter Douglas launched its first aluminum ceiling products (quickly popular for their unique designs and easy installation).
Creating primary aluminum is an energy- and resource-intensive, three-step process that includes mining bauxite, extracting alumina, and smelting. Though it has become more efficient in recent years, this process still has significant energy demands. Once the aluminum is produced, however, it enters a potentially infinite, cradle-to-cradle life cycle by which it is manufactured into products, incorporated into buildings, collected from razed construction, recycled, and put back into production.
At the Hunter Douglas plant in Rotterdam this process is on full display. Here, scrap metal from engine blocks, injection molds, and construction materials is collected and sorted by the employees. It then goes into a furnace, where it is melted, combined with alloying elements to give the final material the desired properties, and finally cast and milled into coils to await final production.
Continuously improving its recycling processes, the plant has invested in wide casting equipment and new melting ovens that use 50% less energy. This has helped the manufacturer achieve an 85% reduction in energy use and carbon dioxide emissions per square meter of blind between 1970 and 2016. And since maintaining the integrity of the metal is critical to achieving high-quality results, Hunter Douglas obtains its aluminum from carefully selected sources and scrap metal suppliers, who, as committed partners, provide exact material composition data.
High Intrinsic Value
With a relatively low melting point of 700 C˚, recycling aluminum is easy and economically attractive, requiring far less energy than something like steel (which melts at 1600 C˚). Recycling is also much less energy-intensive than primary aluminum production, using 95% less energy than creating it from bauxite. Once recycled, the metal maintains the same properties it had in its primary state. It can be recycled repeatedly without any loss in strength, durability, or stiffness, so products made from recycled aluminum are identical in quality to those made from “virgin” material.
These factors combine to give scrap aluminum a high intrinsic value, making it widely recycled on a global scale. In fact, it is estimated that as much as 75 percent of all the aluminum created since the late 1800s is still in use in some form. That means an aluminum ceiling or window covering produced today may contain material that dates back several decades or longer. And with contemporary recycling programs integrated into industrial process much more tightly, it’s even more likely that that aluminum will live on for centuries, either in its current form or as a recycled product. In a very real sense, aluminum is forever.
Aluminum for Design
With aluminum at the center of Hunter Douglas’s strategy, the company goes to great lengths to develop sustainable products and processes. The use of recycled aluminum versus virgin material, for instance, has increased gradually over decades, with the aforementioned blinds and ceilings now made from up to 98% and 92% recycled aluminum, respectively. Product optimization, such as thinning the slats of the Venetian Blinds, is another sustainability-driven approach that’s yielded reductions in material use and waste.
Aluminum can be formed into a wide variety of shapes, sizes and profiles, giving architects and designers broad creative freedom. Because of its strength-to-weight ratio, aluminum presents fewer structural obstacles to achieving that creative vision. These advantages make the metal a desirable material for a variety of applications, including interior walls, ceilings, curtain walls, and window shades, as well as exterior roofs, cladding and doors. At the same time, with aluminum being softer than steel, these products can be readily cut, drilled and modified in the factory or on site, requiring less specialized equipment and energy.
This ease of formability presents advantages over other materials such as steel, wood and gypsum, giving architects and designers the ability to create custom designs. Recent advances in design software and machining technology have led to more creativity, and nonlinear shapes, curves, topography, and other visual effects that are now being incorporated into many architectural elements, including ceilings.
From Hunter Douglas’ Rotterdam plant, the coils go to facilities around the world where they are cut and/or roll formed to create a variety of products like Venetian Blind slats or ceiling panels. The metal can then be painted, perforated, and customized to meet structural and aesthetic specifications. It’s all part of an approach that reflects Hunter Douglas’s commitment to providing high-quality products and contributes to a more sustainable world.
As the San Gioacchino ai Prati Castello approaches its 120th anniversary — young by Rome’s standards — it stands as a testament to aluminum’s role in the future of building. Just as it did when it was built, the dome reflects the Italian sun and will continue to do so as long as the church stands. If the church is ever razed, the aluminum on the dome will live on forever. It will almost certainly be reclaimed and recycled, evolving to serve other yet-to-be imagined applications.