Although one of our oldest building materials, traditionally covering the domes and spires of city skylines, copper is also a thoroughly modern material offering limitless possibilities for contemporary architectural design, particularly alongside historic buildings. Combining numerous natural surfaces and alloys, Nordic Copper products from Aurubis – deployed in various forms and systems – provide design freedom with exemplary recyclability, sustainability and longevity.
Copper’s unique architectural qualities are defined by its naturally changing patina – which cannot be successfully replicated using other materials with surface coatings. Within a few days of exposure to the atmosphere, a copper surface begins to oxidise, changing from the ‘bright’ mill finish to a chestnut brown, which gradually darkens over several years to a chocolate brown.
Continued weathering can then result in development of the distinctive green patina – or blue in coastal locations. This process is an expression of the metal’s propensity to revert to mineral compounds that resemble the ore from which it originally came. Some rainwater is needed for the patina to form and its rate of development will depend on the water “dwell time” on a surface. As a result, vertical cladding and sheltered surfaces will take much longer to patinate naturally than exposed roofs. Airborne pollution also increases the rate of patination, which therefore takes longer in more remote, cleaner environments than in cities or industrial areas.
The complex combination of factors determines the nature and speed of development of patination, giving copper unique, living visual characteristics developing over time in response to local conditions. Natural Surface Treatments Today, all these naturally developing surfaces can be provided straightaway with the ‘Nordic Copper’ range. The factory processes involved are generally similar to those taking place over time in the environment utilising copper mineral compounds, not alien chemical processes.
The surfaces form an integral part of the copper, generally continuing to change over time, and are not lifeless coatings or paint. The architectural range includes Nordic Standard ‘mill finish’ and Nordic Brown pre-oxidised copper, offering lighter or darker shades of brown determined by the thickness of the oxide layer. Copper alloys include Nordic Bronze and Nordic Brass, which can also be supplied pre-weathered. The innovative Nordic Royal is an alloy of copper with aluminium and zinc, retaining its golden colour and simply losing some of its sheen over time with exposure to the atmosphere to give a matt finish.
The extensive Nordic Blue, Nordic Green and Nordic Turquoise ranges have been developed with properties and colours based on the same brochantite mineralogy found in natural patinas all over the world.
As well as the solid patina colours, ‘Living’ surfaces are available for each with other intensities of patina flecks revealing some of the dark oxidised background material. Repair and Restoration Copper’s patina film provides impressive protection against corrosion and can repair itself if damaged, defining the exceptional longevity of copper cladding, counted in hundreds of years. But repairs and restoration – following substrate or structural failures, or other damage – or complementary extensions to historic copper buildings may still be needed. Unique pre-patinated copper material can now be produced to match the naturally patinated copper on a building.
An original sample from the building is used but initial development can be started with photographs. Often, the original copper removed from a project can be recycled for re-use on the same building.
Combinations of these numerous natural surfaces, diverse forms and innovative installation techniques offer architects a new design freedom – enhanced by copper’s exemplary sustainability credentials.
Copper is a natural element within the earth’s crust which has been incorporated into living organisms throughout the evolutionary process. It is non-toxic and its inherent antimicrobial qualities make it ideal for touch surfaces, including interiors. Sustainability Naturally As a lightweight and flexible covering, structural support demands are reduced, resulting in lower carbon and ‘whole of life’ costs.
Then, at the end of a building’s life, copper retains a high scrap value which drives recovery and recycling. In fact it can be recycled again and again without any loss of performance or qualities, and its lifespan can be regarded conservatively as 200 years when correctly installed.
When copper roofs or facades are replaced, it is generally due to substrate or structure failure, rather than the copper. And Nordic Copper products require no decoration, maintenance or cleaning – saving resources, cleaning chemicals and cost.
Its interaction with the environment has been assessed under the European Reach chemical policy and has no classification/restriction. With an ‘A1 (non-combustible material)’ fire classification to EN 13501-1, copper is suitable for cladding tall buildings, using appropriate constructions. Low thermal movement makes it safe and straightforward to use in any climates and locations. Aurubis is part of the world’s leading integrated copper group and largest copper recycler.
For more information about Nordic Copper and to read project stories visit: www.nordiccopper.com or
email: nordicCopper@aurubis.com
