When I walk downtown, I am always slightly in awe of the construction of these magnificent concrete buildings looming over me. How can people build to such heights? Then my environmental brain kicks in, and I wonder if these concrete edifices are the result of years of planetary destruction. As it turns out, concrete has more potential to be green than I originally thought. If all concrete companies made sustainable production their priority, I dare say it could become the most environmentally-promising building material currently available.
Concrete is versatile, low maintenance, strong, diverse, and affordable. It is also one of the oldest building materials in the world, dating back to both the Roman and Egyptian times. It is a reliable thermal insulator and retains heat inside of the home, but it also cools buildings in the hot summer months. Concrete is also recyclable and can be broken down and used as aggregate when a building is torn down. A 2015 study by the Massachusetts Institute of Technology discovered that concrete saves 20 per cent of the energy consumed by buildings made of wood.
That being said, concrete is still responsible for five per cent of carbon emissions. In order to become the greenest building material on the market, companies have to modify the way they produce their building blocks. Holcim, who recently joined forces with Lafarge, is one of the top ranking concrete company to use sustainable building practices on a global basis.
It takes a large amount of thermal energy to create concrete and that strongly contributes to its large carbon footprint. Holcim and Lafarge are sourcing their fuel from renewable energy resources such as waste and biomass. This production change will help Holcium meet global goals of reducing greenhouse gas emissions to pre-1990 levels, or 40 per cent by 2030. To date, they are on track with a 26 per cent reduction. Using carbon capture mechanisms to prevent high levels of carbon from being released also creates a more sustainable product.
It appears that concrete has potential to be one of the most sustainable building materials, but how do other building materials compare?
Tree sequestration is a popular construction material, and a lot of people think it’s sustainable because forests absorb carbon dioxide while they are growing. However, it is only sustainable if there is a larger plan to replace the wood cut for construction. Even if a company replants the trees and leaves portions of the forest untouched, it is still impossible to replace the natural biological diversity that existed before harvesting. It also takes time to regrow the trees that are used, which reduces the sustainability of this building material.
Another popular building material is glass, but there are arguments to be made that concrete is still the better choice. Glass is a sustainable building material because it is 100 per cent recyclable. Though glass is environmentally-friendly, it is not very durable and requires high maintenance and care. It is also not an efficient thermal insulator in comparison to concrete.
The highest polluting building materials are aluminum and steel, because these products need several materials. It takes six pounds of bauxite ore to yield one pound of aluminum, and the bauxite is strip-mined from tropical rainforests. Aluminum also requires 270 GJ/t of production energy as compared to concrete that only uses 1.4 GJ/t. Obviously, aluminum and steel are not sustainable building options and builders should avoid using them at all cost.
Compared to other options, concrete is clearly one of the best environmentally-friendly building materials available. The next step now lies in the companies themselves. If every concrete company embraced carbon capture and used biofuels, it would help reduce the global carbon footprint and the world would still have a truly reliable type of construction.