The attributes of BlueScope steel may enable the design of sustainable products in the following ways:

• Steel may enable reduced landfill at end of life through reuse or recycling.
• High solar reflectance roofing may enable cooler summer homes and businesses.

Recyclability

Steel is theoretically 100% recyclable: if recovered at the end of each use phase, the life cycle of steel is potentially endless. Recyclability refers to how effectively and efficiently a product or material can be recycled into a new product. Recycling prevents the waste of potentially useful materials; reduces consumption of raw materials and energy; and reduces pollution. Steel is easy to recover from waste streams because of its magnetic properties. This, coupled with its economic value, makes steel the most recycled material in the world by volume.

Globally, over 80% of all scrap steel is captured and is either re-used or recycled.

World Steel Association (2008) 2008 Sustainability Report of the World Steel Industry. World Steel Association, Brussels, Belgium. 34pp.

In Australia, the Australian Bureau of Statistics reports that, in percentage terms, metals have the highest recycling rate of all solid waste generated in Australia, 82%, compared with 74% of concrete waste, 55% of paper waste and 38% of glass waste.

Australian Bureau of Statistics (2006) Australia’s Environment Issues and Trends 2006. Australian Bureau of Statistics, Canberra, Australia. 102pp.

There are two factors that account for the difference between the actual (82%) and potential (100%) recycling rate of steel scrap in Australia:

• Recoverability; in remote locations the cost of transporting equipment to recover building components and the cost of transporting scrap back to a main centre for recycling, may be prohibitive. Also some treatments, coatings and building practices can also increase the cost and complexity of recycling steel; for example, steel reinforcing in concrete can be difficult to extract due to the concrete crushing equipment required.
• Human behaviour; it is a choice whether to send waste to landfill.

Even though there are clear economic and environmental benefits of recycling steel, some scrap inevitably ends up in landfills.

Recycling must be clearly differentiated from downcycling:

Recycling

A material can be recovered and reprocessed into the same material of the same quality again and again, as is the case with steel.

Downcycling

A material is recovered, but can only be reprocessed into another material of lesser quality.

High solar reflectance roofing

BlueScope Steel produces a range of steel sheet with high solar reflectance, that can be roll formed into roofing products and integrated into roof designs to reduce the amount of solar radiation (and consequently heat) absorbed into buildings, improving thermal comfort. The Building Code of Australia (BCA) and New South Wales BASIX classify roof products based on their reflectance. By choosing colours in the lightest two categories, very light or light, designs may qualify for an insulation concession in warm climates. For most Australian climates, the use of these products may also improve the energy performance of a modelled design – when modelling tools are used to demonstrate compliance.

COLORBOND® Coolmax™ steel

COLORBOND® steel XRW

COLOROND® Metallic steel

ZINCALUME® steel

The Building Code of Australia (BCA) and New South Wales BASIX classify roof products based on solar absorptance – the inverse of reflectance – expressed as a ratio between 0 and 1. Solar absorptance values are based on as-new / unweathered product. A value of 0 indicates that a roof absorbs none of the incoming solar radiation, whereas a value of 1 would mean that a roof absorbs 100% of the incoming radiation. Solar absorptance categories of the BCA 2010 for residential (Class 1 & 10) properties; solar absorptance of less than 0.4 “very light”; solar absorptance of between 0.4-0.6 “light”. Solar absorptance categories of the BCA 2010 for commercial (Class 2-9) properties; solar absorptance of less than 0.5 “very light”; solar absorptance of between 0.5-0.6 “light”. Solar absorptance categories of BASIX (BASIX is based on BCA 2009) for residential (Class 1, 2, 4 and 10) buildings in NSW; very light (solar absorptance of less than 0.475); light (solar absorptance of between 0.475 and 0.70).