SA on track to build for a greener future

Eco-wise construction firms take lead in leaving smaller carbon footprint

SOUTH African construction companies are building more green buildings, which use less water and energy, while also reducing the amount of carbon dioxide in the atmosphere. The 10th Green Building Convention 2017 held at Century City yesterday looked at construction and the environment.

The conference, themed “Dare to Lead”, was hosted by the Green Building Council South Africa.

Cyril Attwell, a researcher and director at ARC Projects, in his presentation, “Technology and Materials: Grey to Green – Past, Present and Future”, used examples of some of the firm’s recent projects such as the Gautrain, Portside building (Cape Town), City Deep Container Terminal and the firm’s wind farms around the country to show how ARC Projects had turned waste substances such as rubble and ash to create concrete which needed less cement and water while also reducing the amount of carbon dioxide.

Attwell, giving an indication of how much carbon dioxide concrete contained, said 1 000 litres of concrete had a carbon footprint of about 350kg of carbon dioxide.

“Now that’s rather high. It’s one of the largest contributors to greenhouse gases in the world. One hundred percent of the total world’s greenhouse gases are related to cement. The second biggest commodity after water is concrete.”

Attwell, a scientist, said everything was made out of chemistry and one can change just about anything by changing the energy applied to a chemical and has also applied this concept to concrete.

Giving an example of what ARC Projects has done in South Africa to diminish the 350kg of carbon dioxide , he said he was responsible for designing the concrete used to build the Gautrain project.

“Quite interestingly, the original estimate was the usage of 340 000 tons of cement. We reduced that to 10 000 tons. That is 130 million kilograms of carbon dioxide that was reduced by using ash from Eskom’s power stations. We took the ash from there, as well as from the mine dumps and placed 32% of that, saving 130 million kilograms of carbon dioxide.”

Putting this further into perspective, he said the original cement usage estimate of the project would have needed about 4.5 x 3 kilometres of rainforest, alive for 40 years, to counteract the carbon dioxide produced by building the project (Gautrain).

Cape Town mayor Patricia de Lille said that with the construction boom in Cape Town, the city had approved 90 000 building plans last year.

“Having said that we need to navigate our way together in the drought. We are at the coalface of dealing with the impact of climate change and the drought together with our residents and our businesses. The City of Cape Town has been leading the way in putting together a comprehensive water resilience plan.”