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The green reality of aluminium

It is important to understand the sustainability issues of aluminium. By David Earle

Much has been said in recent months about the need for the construction industry to put its house in order on environmental issues.

Ethical sourcing, designing for deconstruction and minimising in-process waste are all issues that have been raised.

Add to these the improving energy efficiency of buildings and component designs and minimising the toxic effects of the manufacturing process and you have a significant task for the industry.

Since 1991, the International Aluminium Institute has monitored the performance of the large majority of global aluminium mining and smelting operations. The total area being mined at any one time is small – just one sq mile.

The vast majority of the sites are subject to formal rehabilitation plans and agreements with around 80 per cent restored to the native hardwood forest.

Alongside these well established activities smelters have reduced the energy needed to produce alumina from bauxite by almost 70 per cent.

They have a current target of a 10 per cent cut in smelting energy by 2010 and their ever increasing use of hydro-electric energy sources enhances their efforts.

Since 1990, despite a 54 per cent increase in primary aluminium production, the global greenhouse emissions have fallen 32 per cent.

Systems designers and fabricators make every effort to optimise bar and sheet stock sizes and use sophisticated software programmes to further reduce the in-process wastage to around 5 per cent, almost all of which is collected and used as clean scrap.

The demand for aluminium windows, roofing, and cladding, particularly in the commercial and high rise residential sectors, remains high due to their well known and proven characteristics such as corrosion resistance and durability.

Its inherent ability to form a protective oxide coating on exposure to air plus the highly durable anodised and powder coating finishes now available make aluminium an attractive and cost effective option for architects and specifiers.

High reuse

Already recognised as a valuable commodity by the construction industry and across Europe, an average of 95 per cent of the aluminium in buildings is collected for recycling.

Such is the demand for clean scrap, its current price is very similar to that for prime aluminium, while the cost penalties for processing powder coated and thermally broken scrap are relatively low due to the efficiency of modern refining processes.

The recyclability of aluminium alloys can be summarised as the rule of 95 – 95 per cent is recovered from buildings, the process saves 95 per cent of the energy needed to produce prime metal and typically 95 per cent or more of the original material is recovered.

David Earle is the technical officer at the Council for Aluminium in Building, a member of the Construction Products Association