23 May 2012 – The Energy Efficiency Manual, written by D. R. Wulfinghoff in 1999, refers to the potential reduction in cooling load using external sun diffusers. His studies show that by installing external sun diffusers, companies can achieve a savings potential of about 70% to 95% of the cooling load. Since effective external shading blocks mostly direct sunlight, while at the same time admitting indirect light, this typically reduces solar heat input by 80% to 90%. In turn, this decreases the dependence on air conditioning to cool internal environments, which as a consequence results in both decreased operational costs and environmental impact.
Glen Pringle, fabrication director at Vital Engineering, which manufactures gratings, stair treads, pressed floors and safety handrails, says that although external sun diffusers are commonly used internationally, the benefits of use are not well known in South Africa and thus they are less commonplace.
“While most installations in South Africa utilise steel external sun diffusers, unless they are corrosion-protected and constantly maintained, they can start looking shabby after a short period of time. This, combined with a lack of education on the bottom-line savings produced by sun diffusers are the most common reasons why they have not gained popularity in South Africa,” Pringle says.
“Vital Engineering has developed a Vitaglass range of GRP fibre glass external sun diffusers which eliminate the inherent corrosion potential problems associated with using steel while at the same time adding a number of further benefits to the equation. Our chosen material of construction is much lighter than steel and because it is moulded, is therefore generally much easier to manipulate to suit specific building designs. On a weight-to-weight comparison, it is also more affordable than steel.
“Because we treat the Vitaglass diffusers with UV stabilisers during the manufacturing process, we are able to increase the durability and longevity of the product, which naturally makes it a viable economic option due to decreased maintenance and elimination of replacement.”
The percentage of sunlight diffused depends on the alignment and orientation of the product as well as the depth of the diffusers. “We supply depths of 20 to 60 mm as standard, with variations on request. The colour of the product can play a small role in heat generation but essentially this is driven more by orientation and ensuring a free air flow behind the diffuser,” Pringle points out.
While some clients prefer to install static external sun diffusers, Vital Engineering does receive requests for diffusers than can be elevated and lowered, either manually or automatically. “Once again this is installation-dependent and while we do not provide the mechanisms for the diffusers, we do provide products that are suited to this purpose,” Pringle says.