Aluminum: How Sustainable is It?

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Aluminum, it’s everywhere: in our cars, trains, airplanes, buildings, soda cans, antiperspirants, dyes and right on our kitchen table in the form of food additives and kitchen utensils. Not a day goes by that we don’t depend on aluminum. Considering it was discovered only about 200 years and available at commercially reasonable prices only for the last 60 years, it is amazing how intrinsically connected it has become to our lives. The most prevalent non-ferrous metal, aluminum is strong and lightweight, recyclable and to many people, indispensable for modern living.

Because of its recyclability, aluminum is one of the green movements poster children. But there are serious issues with aluminum. The process of producing the pure metal we all know and love from its most basic natural occurring state (Bauxite) requires an incredible amount of energy. So much energy, in fact, that you would have to recycle the same piece of aluminum 20 times to just break even on the energy used to create it in the first place. And that is just the tip of the iceberg.

The best measure of the energy used to make a material is the total amount of energy consumed by all of the processes associated with its production; it is usually a tally of BTUs needed to (in the case of aluminum) mine, process, and form the base material into the finished product. It takes 200 million BTUs to make one ton of virgin aluminum. That is 7 times the amount of energy needed to make one ton of new steel.

Produced through electrolysis, aluminum requires massive amounts of electricity: each US aluminum factory uses on average about 2,600 Megawatts (enough energy to power over 2.5 million homes per year). The electricity prices paid by aluminum smelters are a well-kept secret, but there is sufficient evidence to indicate that the industry has secured electricity at below market prices throughout the Western World. As a result of these arrangements, it is likely that world aluminum prices are lower than they would otherwise be, encouraging overuse and reducing incentives for recycling.

So what does all this have to do with the building professions?

The building and construction industry is the second largest consumer of aluminum in the US (behind the transportation industry); in the rest of the world, building and construction is the top user of aluminum. Exterior applications include curtain walls, window frames, siding and roofing, skylights and daylighting assemblies, scaffolding and ladders. Interior uses include wall partitions, hardware, furniture parts, staircases, and heating and air conditioning systems. Architects and designers have tremendous buying power when it comes to specifying this material.

What about recycling?

At first glance, the numbers on aluminum recycling look great. When the metal is recycled, it needs only 5% of the amount of energy needed to create new aluminum. But 100% recycled aluminum is not preferred by manufacturers because of cosmetic defects and the exact performance properties of the material are unknown. 100% recycled aluminum is a mixture of many different types of alloys that were made to order for many different types of applications that are then melted down together. This melting pot of metal presents a risk to manufacturers who are creating aluminum parts with specific tolerances.

To be truly diligent when it comes to recycling, aluminum (like plastic) needs to be sorted by its different properties for optimum recycling. Unlike plastic, aluminum products do not identify the type of alloy they contain. At any rate, recycling should be seen as an ancillary benefit of the material, and not the best reason to use it. America is not very good at recycling anyway. Only half of the aluminum cans we consume end up recycled, and most building components contain aluminum clad around another material, which makes separation difficult. Just because a material is recyclable does not necessarily mean it gets recycled. Ask any contractor during the demolition phase of a project.

The true benefit of using recycled aluminum (from a manufacturer’s perspective) is the cost. Virgin aluminum cost roughly $1,900 per ton, while recycled aluminum is about $310 per ton. The environmental cost of disposal is $5 per ton for both recycled and virgin feedstock.

Post industrial vs. post consumer

It’s also interesting to note the distinction the US Green Building Council gives to their version of post industrial recycling compared to what most manufacturers would call the same thing: according to the USGBC, post industrial waste is material that one industry has sold or traded with another through the marketplace. A good example of this would be an auto manufacturer selling aluminum scrap to a window company. This new definition of post-industrial recycling – one that does not include in-house scrap that is normally fed back into the same manufacturing process – is meant to keep manufacturers honest. A factory feeding their scraps back into the production line is first and foremost good business that happens to help the environment, but if a manufacturer is attempting to highlight their sustainable initiatives to their clients, this is hardly noteworthy.

What about alternatives?

Due to its versatility, finding a single alternative to aluminum is difficult. It turns out that more than 40 years after the film The Graduate, Mr. McGuire was right: the future is still in plastics. Many plastics have some of the characteristics of aluminum, but none have all of them. They also don’t have the same level of embodied energy or messy manufacturing process intrinsic to aluminum.

Carbon fiber is a wonderful, albeit expensive alternative to many different aluminum applications. The transportation industry is starting to see the practical uses of carbon fiber. Half of every new Boeing 787 Dreamliner is made of composite plastic and carbon fiber materials, resulting in a 30% reduction in the use of aluminum compared to the Boeing 777. Carbon fiber also keeps more moisture in the cabin at high altitudes (good for long flights).

Field study

I took my findings to Emeco, the aluminum furniture company based in Hanover, PA. Emeco has not changed how they have made their chairs since the company was formed in the 1940’s – each piece is still made completely by hand, using skilled craftsmen. It was truly remarkable to see how they use a very simple kit of modular parts to create a huge variety of chairs. Their simple, straightforward approach has attracted the likes of Frank Gehry, Philippe Starck, Jean Nouvel and many more world famous designers to create products for them. Emeco is even in MoMA’s permanent collection.

Each chair starts out as a series of sheets of aluminum that are then punched, formed, welded, tempered, anodized and polished into the final product. For many years, the US Navy was Emeco’s sole customer. Each piece is intended to last over 150 years and must pass an internal test for 1,000lbs. of weight. How is that for sustainability?

Like most manufacturers, Emeco is concerned about the environmental impact of their products. In addition to using recycled aluminum for all of its chairs, they are planning to introduce their Navy Chair made entirely of PET, a 100% post-consumer plastic from soda bottles. This introduction enables them to hit certain price points that were previously unavailable to the company.

The Good Design Factor

Emeco can be distinguished from most other manufacturers using aluminum because of the nature and design of its products. In a sense, “using aluminum is using aluminum,” and the quantity and concentration, for some, may not be a significant differentiator. But, Emeco products, by the nature and quality of their design, are intended to have a lifespan that exceeds most other products by a large factor: the design does not change or become tired, and the product does not significantly degrade. This long-term usage provides a persuasive argument for the substantial front-end energy investment.

Emeco’s example of good, timeless design can be translated to many sectors throughout the design industry. What better way to be sustainable than to design furniture, buildings or even vehicles that are in continuous use for many decades, if not centuries? As noble as recycling is, it still uses energy to enable the object’s reuse.

In far too many situations, however, aluminum is used by manufacturers for decorative purposes and in situations where adequate substitutes are available. When the carbon footprint of materials becomes an issue in design (and it will), the complete picture regarding the use of aluminum will surface, and changes will be required. Aluminum is a great material for certain applications, but because it can never be recycled in a closed loop environment, it will always have inherent characteristics that are not sustainable.

But that should not be an unacceptable constraint. Design has been and always will be about problem solving. The continued use of aluminum seems certain, but perhaps its use will be more circumspect.