The Concrete Institute points out some of the misconceptions about sustainable building with regards to concrete.
While the embodied energy (carbon dioxide) of pure cement is high at about 900kg per ton, when used in concrete with additional secondary materials, the embodied energy of concrete can be as low as 90kg per ton.
“This is an important factor for green building,” says Bryan Perrie, managing director of The Concrete Institute.
“The current average worldwide consumption of concrete is about one ton per year for every living human being which, cumulatively, is massive. It should, right at the outset, be remembered that buildings are not constructed out of cement but rather from concrete, of which cement is but one ingredient,” he states.
“In any event, the concern about cement’s environmental footprint also stems from ignorance. Despite the extensive use of concrete in the world, the cement industry only accounts for about 5% of man-made carbon dioxide emissions worldwide. About 40% of this comes from burning coal and 60% from the calcination of limestone,” he explains.
According to Perrie, there are generally many misconceptions when it comes to establishing true sustainability in the built environment. He also says that since most assessment ratings award points for various sustainability initiatives during the design and life of the building, this often leads to chasing points for a particular rating rather than concentrating on real sustainability.
Aiming for zero levels in primary energy consumption, carbon emissions during construction, waste and water consumption, coupled with the total elimination of unsustainable building materials, would be more appropriate sustainability measures, he suggests.
“This has now become the quest of a few major corporations globally and, to me, is a far more pragmatic approach as it focuses on sustainable issues by setting targets rather than just scoring points. The zero target may not be easy to achieve, but it is a worthwhile target to strive for,” Perrie says.
The Concrete Institute also believes that not enough attention is being paid to the use phase of a building or structure, is the period after the construction phase right through to the end of life of the structure.
“Research has shown that the long-term, cumulative benefits of considering the whole lifecycle of structures are staggering. This is a factor that simply cannot be ignored when it comes to assessing true sustainability in building,” Perrie adds.
The Concrete Institute
Tel: 011 315 0300
The energy consumed for raw material extraction, transportation, manufacture, assembly, installation, disassembly and demolition of a product system over the duration of the product’s life.
Captions: The embodied energy of concrete is often lower than traditionally expected and contributes to sustainable building.