The South African building industry has been reliant, for many years, on conventional methods of construction such as brick and mortar, largely due to the lack of influences from the foreign market during the period before democracy and skill set’s past down from generation to generation.
Timber construction goes back as far as our recorded history and needs no introduction; however building codes such as SANS 082 have been developed to regulate timber structures and their performance. Similarly, light steel frame structures, or engineered light weight structures have been in existence in main stream construction for over thirty years. Recently this method of construction has become a standard form of construction in South Africa under the building code of SANS 517 and is recognized by building authorities and financial institutions. Both timber and light steel frame form part of light weight construction, for the sake of this article on sustainability, I will concentrate on the latter so as to promote the sustainable awareness of the younger of the two methods.
Light Steel Frame Building offers designers and building owners the opportunity to minimise energy wastage during building operations as well as during the life of the building.
The primary steel industry worldwide has in recent times vastly improved production processes to minimise energy consumption and pollution. Furthermore, a large percentage of all scrap generated is re-used in electric arc furnaces to produce new steel, resulting in significant energy savings and a reduction of pollution.
As light steel frame buildings are an engineered building method, the use of materials is optimised offering savings in energy used to produce the materials. The mass of a wall in a Light Steel Frame Building is less than 10% of that of a double skin plastered brick wall. It follows that significant energy savings are achieved merely in the transport of the materials to the building site. Furthermore, wastage of materials on site is minimised, again reducing energy wastage by obviating the need to remove truck loads of building rubble after completion of the building process.
Important to note here that by eliminating organic materials such as timber as a sub-structure is by no means neglecting such a material. Timber as an external or even structural component is able to be incorporated with the engineered light steel frame structure providing a pleasing aesthetic effect in the structure, whether it is a visible or hidden component. This of course would need to be regulated as far as the age of the timber and how often the woodland where the timber is extracted from is allowed to grow. Deforestation in area’s where timber is not allowed to grow for the stipulated period of time, has been well documented in the past and would need to be adhered to should timber remain a sustainable material to build with.
More commonly though on LSF structures, fibre cement external boards or building planks are used. Internationally, fibre cement facade’s are expressed quite often when simply utilising the flat sheet itself. (ref: Euronit, Swiss Pearl) Locally in South Africa, Everite-Nutec is the largest manufacturer of fibre cement and one of the oldest manufacturers of this building material worldwide. There are a small percentage of imported goods but these would need to meet the standards set out by regulatory bodies. From a sustainable perspective, the use of local renewable materials in the composition of the product would be more beneficial to the end user than imported products. Together with other thermally efficient materials used in the insulation of the structure, LSF structures become energy efficient, in fact to date, are more energy efficient than conventional brick and mortar structures. SANS 204 (Energy Efficiency code) currently out for public comment, details this fact that LSF structures exceed the minimum requirements on energy efficiency. Conventional methods of construction would need to have thermal materials added to current construction methods in order to meet these minimum requirements, which in turn would almost certainly raise the building costs.
However, the most significant energy saving is achieved over the life of the building. Light Steel Frame Buildings can be optimally insulated for each “building type” in the different geographic regions in Southern Africa, resulting in reduced energy wastage for heating and cooling.
All the above factors combine to render light steel frame buildings energy efficient, and sustainable.