Copper and Nature
Copper is a natural element within the earth's crust which has been incorporated into living organisms throughout the evolutionary process. It is an essential nutrient required by virtually all higher life forms and nature is well adapted to making best use of copper, protecting itself from any negative effects. This applies at the most basic levels right up to the most complex metabolic functions of the human body. It also holds true with the long-term effects of man's use of copper in buildings.
Right: copper gutters, down pipes, flashings and
weatherings at Linacre College, Oxford (BREEAM
rated 'Excellent' and Green Building of the Year). |
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Reserves and Recycling
It is estimated that only 12% of known copper reserves have been mined throughout history. Most copper is extracted from open cast mines which can be found in all five continents. Local environmental impact of mining is strictly controlled and refining is carried out close to the main sources of ore. The recycling of copper is a well established practice and its extent follows overall consumption patterns: by 1985, more copper was recycled than the total consumption of 1950. This is due to the relative ease - compared with other metals - of re-using both processing waste and salvaged scrap from eventual demolition, as well as the incentive of copper's value. Today, at least 90% of copper scrap is re-used and about 55% of copper used in architecture comes from recycled sources. |
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Durability and Lifespan
Copper exposed to the elements develops a protective patina over time which can reform if damaged. This ensures extreme durability and resistance to corrosion in virtually any atmospheric conditions and, unlike some other roofing metals, copper does not suffer from underside corrosion. Consequently, it is invariably the supporting substrates or structure which eventually fail rather than the copper cladding itself and copper roofs have been known to perform well for over 700 years. Similar empirical evidence cannot be provided for more recently developed cladding materials such as stainless steel, even though long life spans (e.g. 100 years) are claimed for them. The rate of corrosion from the copper surface decreases with patination and is considered to average between 0.0001 and 0.0003mm per year. For a 0.6mm thick sheet, this equates to no more than 0.5% corrosion over 100 years. The lifespan of copper roofing and cladding can therefore be regarded conservatively as in excess of 100 years, subject to substrate and structure, and this is endorsed by experience. Naturally, this has a significant effect upon comparative whole of life assessments in terms of both energy consumption (and C02 generation) and cost. |
Copper and Health
Copper is an essential part of the human diet - it helps iron-rich foods make red haemoglobin in the blood. Copper is also involved in the formation of collagen (the fibrous protein in bone, cartilage, tendons, and other connective tissue) and protective coverings for nerves.
Further information on copper and health |
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