Innovation and ongoing technical improvements in the coated steel roofing products manufactured by leading Australian multinational, BlueScope Steel, have introduced a number of benefits that support sustainability in buildings.
Designers, MDS Architecture, specified BlueScope Steel’s Clean Colorbond™ steel, in the colour Cape White and the SAFLOK 700 profile, for the 42 000m² roof of the Mall of the North in Polokwane, Limpopo. The roof of this huge retail complex was constructed by Roofing Guarantee.
Wayne Miller, general manager of BlueScope Steel’s South African operations says, “If the future of building is about reducing operating carbon emissions by minimising energy consumption, then known high-end sustainable steel products such as those supplied by BlueScope Steel will have a considerable role to play.”
The benefits of using steel include its high strength-to-weight ratio which allows for wide spans and maximum access to large internal volumes. Facilitating one-room-wide designs, it allows for easily controlled air flow/cross ventilation and natural light throughout the interior. This in turn allows for easier and less energy intensive climate control in summer and winter.
Steel has a low thermal mass which means little energy is needed to change its temperature. Steel cladding and framing is therefore ideal to use in ‘reverse mass’ and lightweight construction. Such methods of construction are most appropriate in tropical, hot, and arid climates. Lightweight materials are more responsive to temperature fluctuations so they cool more quickly at night and less energy is required for this process.
BlueScope Steel has committed considerable research and development resources to the development of its new and improved Zincalume® and Clean Colorbond™ steel sheeting. In addition, the high performance paint system on Clean Colorbond steel is formulated to provide a high level of reflection of incoming solar radiation and incorporates a number of features that minimise maintenance requirements. It offers exceptional colour retention as well as anti-chalking, anti-fungal, and dirt resistance benefits.
“Correctly applied, our product should give a lifespan up to four times longer than the standard galvanised steel or pre-painted galvanised steel variations in a similar building environment,” says Miller.
At the Mall of the North, the white roof surface minimises the fraction of inbound solar energy absorbed and maximises its reflection – resulting in a cooler roof in summer. BlueScope Steel has specially designed its super-polyester paint systems to perform in high UV environments, ensuring that the thermal performance is maintained over a long period of time. Due to the lighter weight per square metre of the aluminium/zinc coating, the heat absorption and emissivity of the upper and lower roof surfaces are minimised, limiting the amount of energy re-radiated upwards and downwards from the roof into the surrounding spaces.
BlueScope Steel products are covered locally by a manufacturer’s warranty but the company is careful to point out that warranties should be applied for prior to the start of building, to ensure that the correct product is being used for the given application and so to maximise the performance of the roofing or cladding. It is also important to ensure that the correct fasteners and flashing material are used to match the performance of the roofing or cladding sheets.