|
“We make four billion tons a year of cement, which translates into about thirty million tons of concrete. That’s almost ten thousand pounds of concrete being poured every year for every human being on the planet.” – Rebecca Dell, The Big Switch |
|
Besides water, concrete is the most used material in the world. If you take a stroll through a big city, it’s easy to understand why. |
|
Unfortunately, concrete is also a massive source of greenhouse gas emissions. And that all has to do with one of its primary ingredients: cement. |
|
Cement and Steel Emissions 101 |
|
Cement and concrete are often used interchangeably, but that is incorrect. Concrete is the ubiquitous grey substance used to construct our many apartment buildings, skyscrapers, and bridges. Cement is the glue that holds the other components of concrete together (rocks and sand). It’s also the reason the concrete industry is among the biggest carbon polluters in the country. |
|
To make cement, you need something called clinker, a key ingredient that acts as a binder. And to make clinker, limestone needs to be heated to a staggering 2,700 degrees Fahrenheit. Achieving such a high temperature currently requires burning a lot of fossil fuels, making cement production a very carbon-intensive process. Additionally, the chemical reaction necessary to make clinker releases mass quantities of nitrous and sulfur oxides leading to negative externalities like acid rain and heart disease. |
|
The second-most used material in our built environment – steel – isn’t so great for the climate either. Global steel production accounts for more carbon dioxide (CO2) emissions than those generated by all of India. |
|
So, before the first light is switched on in a new building, the structure itself is already responsible for significant carbon emissions. This type of CO2 from materials manufacturing, alongside other lifecycle emissions like building construction and the transportation of materials, is known as embodied carbon. |
|
Is There a Solution to Decarbonize These Carbon-Intensive Materials? |
|
Absolutely! |
|
Just as we have solutions like heat pumps and induction stoves to tackle operational building emissions, a variety of strategies exist to reduce embodied carbon from building materials. For concrete, we can heat limestone more efficiently, or we can use cement blends with less clinker. And for steel, we can replace the fossil fuels currently integral to the manufacturing process with green hydrogen, use renewable energy to power smelting furnaces, or even bring in sustainable replacement materials like cross-laminated timber (CLT). |
|
How the Inflation Reduction Act Will Help |
|
However, using greener materials is often more expensive than the status quo. Fortunately, the Inflation Reduction Act (IRA) makes eliminating embodied carbon a priority, allocating $4.5 billion across five programs to achieve such a goal. |
|
Most notable is Section 60503, Use of Low-Carbon Materials. This program allocates a whopping $2.15 billion to construct or modify federal buildings with low-carbon materials. While the legislation does not go into detail about what these materials will be, our guess is that much of it will target embodied carbon from concrete and steel, especially given the size of most federal buildings. |
|
Another IRA section worth mentioning is 60116, which provides $100 million for the Environmental Protection Agency to identify and label low-embodied carbon construction materials. |
|
This process is far more important than it may sound. Embodied carbon is only now emerging as a hot topic in decarbonization, and there is little research on the subject in comparison to operational emissions. In order to quickly transition to low- and zero-carbon concrete and steel, it’s vital that engineers and developers have an easy way to identify greener products. |
|
What’s Next? |
|
Once this IRA money is distributed, we’ll be sure to update you on the specific strategies the federal government is pursuing to reduce emissions from embodied carbon in industrial building materials. If you want to learn more in the meantime, we suggest reading this excellent report by RMI. |
|
And if you just want to see an example of how amazing low-carbon architecture can be, check out McDonald’s Chicago Flagship, designed with CLT and featuring a floating glass garden. |
|
Photo by kalyanby. Source: Shutterstock. |
