The environmental and socio-economic impact of clay bricks in South Africa
The building sector has been linked to high CO2 emissions and global climate change, a concern that affects us all. A first step towards improving the sustainability of building materials is to understand the extent and source of the environmental and socio-economic impacts.
In light of this, the CBA commissioned two detailed scientific assessments to understand the environmental impact of clay brick production and use in South Africa. The independent studies were conducted by The University of Pretoria. The CBA also commissioned a social LCA which was conducted by G1 Consulting & Associates and Equispectives Research & Consulting Services.
This brochure provides a high-level overview of these studies and the key take home messages for those involved in brick manufacturing in South Africa.
ISO 14040 and 14044 standards
The study commissioned by the CBA was conducted in accordance with the ISO 14040 and 14044 standards, with an external review by Quantis International, to assure the highest quality standards. The LCA is underpinned by specific production data from 86 out of the 102 clay brick production sites in South Africa, covering 95% of the bricks produced in South Africa. Data from the informal sector was not considered, as this is estimated to represent only 3% of the market. Production data for each manufacturing site was collected for one year (2013), and takes into account raw materials, electricity and fuels input into each of the production steps, as well as all transport steps.
What was assessed
Brick firing technologies differ substantially in terms of their infrastructure requirements, fuel type and combustion procedure. The study covered six different kiln types used in South Africa:
- CLAMP KILN, the most widely used in SA typically producing stock bricks. The kiln is fired with coal or fuel oil, and burns for up to two weeks.
- TUNNEL KILN, an advanced firing technique, with most face bricks produced in SA produced by this technology. Firing is with gas, fuel oil or coal of specific quality, and continues for 48 to 72 hours.
- TRANSVERSE ARCH KILN (TVA), a continuously-fired kiln burning coal and/or gas, with the complete firing and vitrification process taking up to a week.
- VERTICAL SHAFT BRICK KILN (VSBK), a continuous process in which bricks move down a vertical kiln through a central firing location. The firing process takes only 24 hours. VSBKs are typically coal-fired.
- HOFFMAN KILN, an old technology and the first type of continuous kiln in which coal is dropped from above into a tunnel constructed of refractory bricks.
- ZIGZAG KILN, the least used technology in South Africa, has a long fire zone and uses suction fans to draw the fire from one batch of bricks to the next batch. Internal fuel (coal) added to the clay mix fires the kiln.