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Green Thursday- An innovative way to build houses

iThursday, Jun 25th, 2015 comments by Barbara

Building affordable homes in Johannesburg

In 2011, a new problem was became apparent in the housing market: House ownership among the emerging South African middle class was not growing as housing was unaffordable. This growth stunt was attributed to building costs and alarmingly high property prices amongst other reasons.

Sasol, FNB and Tower Technologies (a subsidiary of EnviroServ Waste Management) teamed up in order to address this issue, by creating a new and affordable building material. By using this new technology, the companies aimed to reduce pressure on existing resources, create jobs and be environmentally- friendly. [1]

 A new building technology 

Conventional houses in South Africa use brick, which can be a more expensive material to use. The new building technology makes use of bricks constructed from mining and manufacturing by-products, such as fly ash.

       Diagram: A flow chart showing the products used to create the houses

The fly ash comes from Sasol, which by-product produced at their Secunda site. When fly ash and cement are mixed together they form a foam-like substance. That substance is then mixed with a polymeric binder. The polymeric binder, used to coat and for other construction purposes, binds the rich foam material together. Once the foam is bound it is place in panel steel structures. The steel structures are designed with specific measurements in order build a house of a predetermined size. [1]

Image: Sasol Secunda, South Africa [2]

Diagram: Showing how fly ash is created in a coal fired power station [3]

Conventionally built houses are different in some aspects to houses built using the techniques described in this article. The table below aims to show a few similarities and differences between the two.

A table comparing conventionally built houses and houses built using by-products [1]

Conventional houses

Using by-products

Construction time is lengthy

Houses constructed in 5 days

Material is expensive

The majority of the materials are by-products (inexpensive)

Selling price is expensive

10 to 20 percent cheaper than conventional houses

Degrades the environment

Helps the environment by using by-products

Construction cost is expensive

Construction cost is considerably lower

Construction: energy intensive

Construction: less energy intensive  

Cement usage is high

Cement usage is considerably low

Physically attractive

Same feel and look as conventionally built houses

Thermally less superior to by-product houses

Thermally superior as compared to conventional houses

Material transportation can be difficult

Easy transportation of construction panels

High carbon footprint (manufacturing bricks etc)

Panels are constructed from waste streams (low carbon footprint)

SABS approved

SABS approved


The project to build houses using this technique was started in Johannesburg and after the construction of 5 houses the developers received 50 orders to build more houses and had a waiting list of 120 people. The initiative seems to be a success in that it is attracting the intended market. It was noted that people between the ages of 35 and 45 were most interested in purchasing such homes. In this category most of the interested people are second time buyers and earn an average of R15 000 and R50 000 a month. [1]


[1] Joburg. 2011. A new way to build houses. [ONLINE] Available at: [Accessed 24 June 15].

[2] Annual Report 2011, (2011), Sasol facilities in Sasolburg, South Africa [ONLINE]. Available at:[Accessed 24 June 15].

[3] Fly Ash Australia, (2010), Coal Fired Power station [ONLINE]. Available at: [Accessed 24 June 15].

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