While light weight steel frame building has been used elsewhere in the world for decades, it has only recently been introduced to the Southern African market. The Southern African Light Steel Frame Building Association (SASFA) has now published the SASFA Code for Light Steel Frame Building, and are currently introducing it to the market through a series of 1 ½ day training courses in Johannesburg, Durban and Cape Town.

The Director of SASFA, John Barnard, is one of the prominent speakers on the training course, along with Lex Somerville, who is an independent building materials and construction consultant in Australia, and Dr Hennie de Clercq, the Executive Director of The SA Institute of Steel Construction.

Light steel frame building has a number of advantages compared with conventional building methods, including the faster process of construction and accuracy as well as allowing the flexibility to build in stages. There are also quite a few energy saving advantages to using light steel frame building. Barnard explains the benefits, starting with insulation.

The main purpose of insulation in building is to maintain internal temperatures at comfortable levels. Insulation works hand in hand with the principles of heat movement. Heat moves through three basic mechanisms - radiation, convection, and conduction.

For example, in summer the high temperature outside is transferred to the inside of a building mainly through the windows, external walls and roof of the building inside. This process is known as heat gain. In winter, the reverse happens and is known as heat loss.

In summer, to counter the effect of in-coming heat, appliances such as air-conditioners and fans are used, requiring large amounts of electrical energy. By implementing proper insulation, the rate of heat movement is slowed down considerably, reducing the need to cool interiors.

The resistance of an insulating material to heat flow is quantified using the R-value'. The higher the R-value, the more resistant the material is to heat flow. Depending on the geographic location in South Africa, the recommended R-values for walls of low rise buildings range between 1.9 and 2.2 m2 .K/W.

Insulation is added as a normal part of the building process for light steel framing, resulting in R-values within the recommended rating. This can save from 10 to 30% of electricity consumption with regards to heating and cooling.

About six months ago, Barnard worked with a specialist consultant to compare the internal temperatures of light steel frame buildings (designed and built according to the SASFA Code) with those in conventionally built buildings (brick and block walls). Sophisticated software developed by the American Department of Energy was used in the comparison. The result indicated that light steel frame houses, compared to brick structures of the same dimension and orientation, could offer energy savings of up to 33% when the internal spaces are heated / cooled to optimal internal temperatures.    


Another form of energy demand is embodied energy', defined as the total amount of energy consumed by all the processes involved in establishing the building, including the manufacture of the building materials and components used. It goes from the production through to the delivery and assembly of the final building.

Embodied energy accounts for up to 20% of the total energy consumption of a building over a period of 50 years and includes operational energy use. SASFA have compiled a report comparing the embodied energy per kg of material, with reference to Australian information and specific software data.

To produce galvanized steel sheet requires some 38.0 MJ/kg, significantly more than the 1.5 MJ/kg for concrete blocks or the 2.5 MJ/kg of clay bricks. This would suggest that the use of concrete blocks or bricks would be more sustainable from the embodied energy perspective than the use of steel. However, this is comparison is based on mass (kg).

Barnard explains that, when the actual use of materials in a building is considered, a totally different picture emerges. When compared on a unit mass basis, galvanized steel sheet may appear to be less sustainable - however the mass of steel used in a structure is vastly less than the mass of bricks or blocks. Hence the embodied energy of a light steel frame wall (measured in MJ/square metre of wall) is less than a quarter of that of a double leaf plastered brick wall.
While on the subject of mass, it should also be noted that less energy for transport is needed with light steel framing, as the total mass of materials used is less than 10% of that of a conventionally built building. From a logistics view point, there is not only a lower mass of materials to bring to site but also to remove once construction has completed. On a conventional building site a vast quantity of rubble is generated, which typically has to be removed after the building has been completed. Due to the very low levels of scrap generated when building light steel frame buildings, rubble removal is hardly required.    
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Recycling also plays a big part in sustainability of using steel compared to other construction methods. Steel has a recycling rate of plus 70% and can be either reused for other buildings, or steel producers can manufacture new steel products from scrap. In South Africa, more than 30% of South African steel is produced from scrap or recycled steel, which conserves further energy in production. The same applies to the other materials used.

Barnard explains that the SASFA does not believe that light steel frame building will replace conventional building methods overnight - it is however an alternative method to be used for low rise buildings. While the SASFA Code covers single and double storey buildings Barnard does point out that it doesn't mean that light steel frames are restricted to only small-scaled buildings. Six to eight storey buildings are built in the US using the same principles. He has also heard of a 14 story building being built currently in China.

In South Africa, steel frame building is already being implemented in a variety of constructions across the country.

He explains that with the current power situation in South Africa could benefit from construction methods such as light steel framing. Due to the energy saving advantages and sustainability benefits, buildings constructed with light frame steel frames now, would not only be beneficial to the power situation in the longer term, but in the immediate future as well.

Lex Somerville says the amount of enthusiasm he has seen in South Africa, in Durban, Johannesburg and Cape Town during the training course has been unbelievable with regards to light steel framing. He goes on to explain that as far as light steel framing is concerned, Australia is generally regarded as the leader in the industry. However, he says with the approach and attitude he has seen over the past few days, he believes that South Africa could very well take over.

Barnard adds to Somerville's opinion by stating that SASFA regards quality as the cornerstone of the development of the industry in Southern Africa, and he wants to emphasis that although steel framing is energy efficient and could result in cost-savings, it doesn't mean at all that the quality of the buildings is compromised.

Contributed by:

SASFA

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