People like a steel built environment, which is light, open, airy and adaptable. Steel structures mature with age, rather than deteriorate and decay. Steel’s long clear spans mean that interiors can be changed with ease.

Steel frames can readily be adapted and reconfigured to give old buildings a new lease of life. The longevity of a building is fundamental to its overall sustainability.

Most other materials are recycled once to a lesser use. This is referred to as downcycling. Steel can be recycled indefinitely without loss of property or performance. This is referred to as multicycling.

It means steel always has a value, which guarantees that virtually none is ever disposed of to landfill. The multicycling of steel is a self-sustaining system that predates modern appreciation of environmental issues and would continue in the unlikely event that they should ever lessen in importance.

Recycled content is a driver to encourage recycling of materials which would otherwise be disposed of. However, it is not a suitable driver for metals that are already recovered and recycled close to their maximum.

Specifying recycled content for steel does not have any beneficial environmental effect, but can distort the market and result in unnecessary transport costs and emissions. All steel is recyclable and will be multicycled many times without any artificial stimulus.

A.It is accepted that, to be sustainable, a solution needs a sound economic basis. Steel is fast, efficient, predictable and safe.

Production is highly automated and site operations are not labour intensive. Steel is the cost effective solution and delivers long-term value through flexibility, adaptability and lasting appeal.

The thermal mass of a building can be used to reduce the requirement for active heating and cooling. People instinctively associate the cool inside churches with their mass, but it has far more to do with the lack of windows and low solar gain along with an absence of heat generating electrical equipment and lighting.

Optimum thermal mass is mobilised from the first 100mm thickness of concrete floor slab, which is available in standard steel-framed construction. The extra mass associated with heavier weight structures is a waste, which is compounded by the larger foundations required.

The World Steel Association collects a lot of data, which has been used to calculate the value of 0.762 t/tonne using the System Expansion methodology, which is the highest ranked method in the ISO 14040 series of standards.

There are other values in circulation, some are higher and some are lower than 0.762 t/tonne. Most are derived by less rigorous methods than System Expansion in an attempt to have a common method for all materials. They are intended to provide a fair comparison, but do not take account of steel’s unique environmental qualities.

Almost no steel or indeed any metal is ever intentionally wasted. It is too valuable. Throwing away metal is like throwing away money.

A recent survey indicated that no more than 1% of structural steel ever goes to landfill. The rest is multicycled indefinitely.

An alloy is a partial or complete solid substance made up of one or more elements in a metallic matrix. Alloying one metal with other metals or non-metals enhances its properties.

It is graded on composition and physical properties.

The density of steel varies based on the alloying constituents; however, it usually ranges between 7.75 and 8.05 g/cm3 (0.280–0.291 lb/in3).

When steel doesn't contain aluminum, boron, chromium, cobalt, columbium, molybdenum, nickel, titanium, tungsten, vanadium or zirconium, it is considered as carbon steel. In addition, in carbon steel copper does not exceed 0.40 per cent, manganese 1.65 per cent and silicon 0.6 per cent.