Rethinking concrete to build more sustainable cities

One “boring” aspect of how we built cities going forward is also a very old one, concrete. A material that’s been around since the Romans, humanity has produced an astonishing volume of it and is still doing so at a no less astonishing rate.

Concrete is quite literally the foundation of our modern civilization. It is relatively cheap, strong, made from resources that we (seemingly) have an abundance of, can take many shapes, and has a very long lifespan. […] We use more than twice as much concrete as all other building materials combined. This makes it the second most used material in the world (after water) and the most consumed man-made material with a staggering 10 billion tons of it produced each year. This would be enough to cover all of the UK in a 2 cm layer of concrete or to build 1,700 Hoover Dams, or 90,000 Burj Khalifas each year.

If you are paying attention to the various needs and debates around decarbonizing our economies, you’ve probably seen some numbers and hoped-for technologies around the huge carbon footprint of concrete, but it also has massive impacts on ecosystems, like depletion of sand, water availability concerns, and the fact we too often ignore that it’s not a material appropriate for all climates and contexts.

The uncontrolled taking of sand can devastate local habitats and species. In Africa, China, and Southeast Asia, where we see huge population growth, extracting sand from rivers and lakes creates standing pools of water that become breeding sites for mosquitoes carrying malaria and other emerging diseases. […] Right now about 10% of the world’s industrial water use goes toward concrete production; this does not take into account the water used later on the building site.

The article linked above goes into more detail about those impacts and how our societies might build smarter, like considering designing for longevity, lengthening the lifespan of the material with design for disassembly, urban mining through reuse of what’s in the system, and replacing concrete with sustainable materials that are regional and bio-based.

Fully understanding the environmental impacts we are creating along the entire production chain will then inform a solid transition strategy. There is a path lined with eco-friendly and local materials to build the sustainable megacity of tomorrow — let’s be brave enough to take it.

The author finishes with some inspiring new projects, including one example of the use of wood in new and sustainable ways, something that’s being done more frequently in Scandinavia and could certainly be relied upon quite a bit more here in Québec and Canada.

Mjösa Tower (Mjøstårnet) is an 85.4m-tall mixed-use timber building in Norway. It has 18 floors and includes a hotel, private homes, and office spaces. It is the third tallest building in Norway and has been credited as the tallest timber tower in the world by the Council on Tall Buildings and Urban Habitat.