Sector Focus: Green steel

CW Staff , January 28th, 2012

The development of steel-frame construction made it possible to build tall, leading to the skyscraper boom, while light-steel framing is being touted as the sustainable answer for residential and commercial construction

Steel-frame construction refers to a technique whereby a building, usually a tall tower, is built by means of a skeleton frame comprising vertical steel columns and horizontal I-beams in a rectangular grid to support the floors, roof and walls, which are all attached to the frame. The façade of the building, ranging from stone to reinforced concrete, glass or even sheet metal is also anchored to the frame.

Light-steel framework, on the other hand, uses thin sheets of galvanised steel as a building material for rough framing in commercial or residential construction. The sheets, which are roll-formed into the final profiles for framing, are zinc-coated or galvanised for protection against oxidation and corrosion.

The speed of this construction method, coupled with the perceived sustainability or ‘green’ benefits of steel, has resulted in an increase in light-steel framework construction for a range of applications, from houses to factories and office blocks.

It can also be used for partitions within buildings and for framing interior walls.
“The focus on sustainable building design is creating a fundamental shift in the way that new projects are approached by architects and engineers.

As they search for material solutions that provide energy and cost efficiencies, steel is available to help them meet the highest sustainability standards,” commented Mark Nowak, president of the Steel Framing Alliance of the US.

Steel is, of course, the most recycled material on the planet. All steel products contain recycled steel, while steel framing, in particular, has a minimum 28% recycled content.

This means that, as a building material, steel framing is completely recyclable – a major advantage at a time when the construction industry is looking to reduce its carbon footprint and optimise its resource use.

“A typical 185.8m² home [in the US] requires about 40 to 50 trees, but with steel, only the equivalent of about four scrapped automobiles is needed,” highlighted Nowak.

Compared to many other building materials, steel is routinely collected in aggregate quantities from construction and demolition sites, and recycled into new steel products.

The Steel Recycling Institute of the US reports that the recycling rate of structural steel products in the US is 98%, the highest rate for any building material. In addition, steel is recognised by all major ‘green’ building rating systems and standards, including ASHRAE Standard 189.1 and the USGBC’s LEED programme, which is widely applied in the Middle East.

In terms of the latest developments, Nowak said the 2012 International Energy Conservation Code (IECC) calls for the increased use and thickness of continuous insulation on the exterior walls of cold-formed steel buildings.

In response to this, the steel industry has developed innovative systems that effectively eliminate or reduce thermal bridging. These include steel panels embedded in foam insulation; ‘warm wall’ design, where steel is placed entirely inside the insulation layer; and more cost-effective ways to use continuous foam insulation.

“With so many challenges to the building codes, designers and manufacturers would do well to take a whole building design approach to the energy package, using readily available simulation tools,” commented Nowak.

“Increased interaction between different professionals involved in the design process would ensure greater efficiencies. By getting involved in the early stages of a project with structural designers, steel framers and manufacturers could ensure a high-performing building, without having to add exorbitant costs.”

There are various companies involved in the steel framework sector in the Middle East. Framecad Solutions is a New Zealand company that set up shop in Dubai in 2008 in order to promote this construction method in the region. As an engineered product, meaning it is manufactured and assembled in a factory before being delivered to site, steel framework is becoming more popular due to its perceived benefits and advantages.

“There are many standard sizes used in the industry, but one can use any size or shape, depending on the application,” said Nader Elhaji, regional director for steel-framing supplier Framecad Solutions. “It is an engineered product, and therefore there are no applicable limits on the building shape or size.” The greatest economic viability is derived from structures up to nine storeys, added Elhaji.

Speed, efficiency and cost-savings are the main benefits. “Time-saving is one of the biggest advantages,” according to Kirby Building Systems. “Steel is 50% faster to erect than conventional concrete buildings.”

Other suppliers concur. “The structure is typically built using CAD/CAM systems, with panels and trusses assembled off-site, which means as much as a 35% reduction on construction costs, and a higher speed of construction than traditional systems,” explained Genesis Manazil Steel Framing CEO Maged Mostafa.

Mostafa pointed out that steel framework also adds an element of predictability to the construction process, in that quality and output can be controlled more carefully. “This enhances the confidence and certainty that a project will meet all of its targets. The quality of work is also not entirely dependable on the quality of workmanship, or on weather conditions, as 80% of the activity is carried out in an indoor, controlled environment.”

Critical to these benefits are the steel frames themselves, as well as the technology used to fabricate them. Steel frames are lighter, cost-effective, faster to erect and durable. Perhaps more importantly, the latest technology has automated the steel frame construction market. It has reduced the need for skilled labour that the market required previously, and has sped up the engineering, fabrication and erection processes.

“The more we can utilise steel in smaller structures, such as residential and light commercial buildings, the more we can save on materials used and overall construction costs,” said Mostafa.

A potential disadvantage is that steel framework is not suited to all projects, depending mainly on the size in question. If a project is particularly large, it could mean that the steel framework required cannot be manufactured in a controlled factory environment, which could affect quality.”