The silent assassin

The construction industry is receiving attention for its increasing depletion of natural resources. What are the alternatives? KERRY DIMMER reports.

The construction industry is considered to be one of the causes of environmental pollution and degradation, given that it is a large consumer of land and raw materials, and is a high waste generator. Marc Sherratt, architect and founder of Marc Sherratt Sustainability Architects, calls the current construction industry “the silent assassin of global ecological diversity”, adding that the sector “doesn’t apply the same focus on the problem as the agriculture, packaging or transport industries, and yet its effect is arguably greater.”

The stats confirm the concerns. The World Watch Institute says construction consumes 40% of the world’s usage in raw stones, gravel and sand, and 25% of its virgin wood each year. Bimhow, a construction blog, says the industry is responsible for 23% of air pollution, 50% of climatic change, 40% of the pollution of drinking water, and 50% of landfill waste. Sherratt adds to the list: globally, buildings produce one third of the world’s CO₂, and consume 12% of the world’s fresh water.

“Other forms of pollution are less obvious: light pollution that is seen from space, urban heat islands, and heat pollution that causes cities like Dubai to be hotter than the desert that surrounds it. The point is that land buildings have led to a planet that has been designed for a single species: us! We have not accounted for the significant effects that construction has on the environment.”

The “us” is, however, doing something about it, with innovative alternatives to natural environment resources. Plastic building blocks is one example – in a process that is being perfected by a South African design centre that turns plastic waste into brick-like blocks called EcoArena.

Green concrete is another potential innovation; it’s something the University of the Free State is studying in an attempt to “unearth new ways to produce concrete”. This alternative replaces raw materials with industrial waste or byproducts such as fly ash from coal-burning power plants and pulp/paper mills. Crushed waste glass or recycled concrete is used as the aggregate instead of natural sand and stone.

At Freedom Park, Cape Town, the EcoBeam system was used to build houses, whereby brick-and mortar was replaced by sandbags, which ironically is a decades-old technology. The manufacturer claimed that the carbon dioxide emission of one square metre of sandbag wall was 96% less than a conventional brick wall.

The Council for Scientific and Industrial Research (CSIR), in collaboration with the road construction industry, has also been giving attention to the waste product potential for pavements and roads. A demonstration project, on a section of the R80, has proved successful and although the CSIR has yet to release its technical findings, it has claimed there is potential in using specified waste plastic materials.

Meanwhile, Dr Wil Srubar of the University of Colorado Boulder believes that growing building materials using biology is part of the solution in creating low-carbon and carbon-storing bio-based building materials. His lab has been using coccolith shells – tiny micro algae that grow in seawater – as an input in making cement. Srubar’s team is also giving attention to hemp fibre, compressed into structural boards, as an insulation material.

The construction industry will ultimately have no choice in adopting such solutions, although, as Sherratt says: “How we build and what we build with is difficult to change given our inherited consumption habits. I suggest that perhaps the new buildings of the future will be the ones designing us to do better rather than the other way round!”