It is believed that copper was the first metal to be found by men and used in the manufacture of tools and weapons. This occurred in the last period of prehistory, more than 10,000 years ago, in the so-called Metal Age, when groups, until then nomadic, started to become sedentary, developing agriculture and starting the first urban settlements. Copper has since been used in diverse ways. Used for decorative objects, jewelry, automotive parts, electrical systems, and even for dental amalgams, the material has had huge demand. In architecture, copper coatings are greatly appreciated for their aesthetics and durability. But a factor worth mentioning is that copper can be recycled infinitely, practically without losing its properties.
This is an important feature, since the demand for the material is expected to increase significantly in the future. A 2017 World Bank report “The Growing Role of Minerals and Metals for a Low Carbon Future” highlights how demand for metals such as aluminum, copper, lithium and others will increase with the large-scale use of solar, wind, and batteries. The document emphasizes that effective recycling measures are essential so that the extraction of copper in mines does not need to increase significantly. The copper recycling process consists of collecting and classifying scrap according to its purity. Depending on their level, they can be sent directly to the smelter (in the case of pure copper) or subjected to a treatment, forming anodes or other alloys.
To say that copper is a green material will never be an exaggeration. This is because, in addition to its infinite possibility for recycling, when exposed to the weather, it develops a greenish patina, like a thin layer of protection that leaves the inner part of the piece intact. This is even an aesthetic sought by many designers, while others prefer the orange and polished tones of the original pieces. With the eight examples below, we may see the different possibilities of use and appearance that copper can have:
In the project The Dallas Holocaust & Human Rights Museum / OMNIPLAN, for example, the copper coating, still quite recent in the photos, carries the bright and orange color most characteristic of the material. According to the architects, the project's external and internal materials embrace the idea of reusing materials and recyclable content. "Copper has an infinitely recyclable life, making it highly reusable for future generations."
At JKMM Architects' Lahti Travel Center, copper works simultaneously to highlight the urban infrastructure and to integrate it into a historic red-brick building. Copper is part of almost all transport equipment, bringing reflections and a subtle highlight to the structure. In the building designed by LAN Architecture, with offices in the city of Lille, France, it was decided to create a striking difference between the new construction and its urban context. In this case, the copper is apparent in several different forms, already with a gray patina. “The building's surroundings were conceived as a way to visually reinvent the city. The facades are characterized by different designs in response to their orientation, their use and their thermal requirements. In this way, predominantly glass areas, some of which have a double film, are juxtaposed to different forms of more or less porous copper cladding.”
Copper also has an advantage in reducing the need for maintenance. For the Skelleftea Kraft Office Building, from General Architecture, in Sweden, the strong structure and articulated tectonics of the new building is based on a general three-dimensional order and is related to a classical rational tradition. The use of pre-oxidized copper on the facade meets this aim, optimized for durability and minimizing the cost of maintenance over time. Nine thousand copper panels are anchored to a hidden stainless steel structure. The result is an outer layer consisting entirely of non-organic materials.
In the oxidation process, the copper pieces form a layer called verdigris, responsible for the greenish appearance, which also protects the internal part of the piece. In fact, copper is a material that drastically changes its appearance, ranging from orange to greenish, going through gray and even black. Considering how the material will age can be a wise decision, as was the case with Suvela Chapel, Finland. In this project, the architects point out that “the tactile sensation of the material has a deliberately strong presence both inside and outside the building. The exterior cover is completely covered with copper to highlight the unity of the building's varied volume. Copper was an ecological choice of material for the outdoors. It is durable and recyclable and therefore sustainable. It also ages well and acquires a beautiful patina over time.”
At Villa Drei Birken, from Plasma Studio, copper and wood are exposed to a natural color variation caused by the atmospheric influence of sun, rain, and snow, which further increases the integration of the building into its context over time. The coating pattern of the copper tiles in the Kirkkonummi Library, designed by JKMM Architects, together with the oxidation of the material, are related to its reconceptualization of its maritime heritage. The main building of Aalto University, by ALA Architects, highlights the final stage of oxidation. A greenish texture, which varies in relation to orientation and exposure, brings out a different dimension to copper as an architectural material.
Through these examples, it is possible to observe how diverse copper use can be. It has already been useful to humanity as the source of our first metal tools, and it should be very important in future efforts to reduce carbon emissions. And in addition to being indispensable to multiple aspects of our daily lives, it can acquire different shapes and appearances when applied to the construction of buildings.
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