CA06 - The Biggest Enemy
Concrete isn't going anywhere.
THE TOPIC
Concrete is a lot like death and taxes. It’s unavoidable and it’s a big bad villain. Concrete is notoriously bad for the environment. Concrete alone contributes 8% of the total GHG emissions in the world! That’s difficult to put into perspective but that’s massive!
The problem here, just like death and taxes, is that concrete isn’t going anywhere. It’s an incredible material that has in many ways shaped the modern world. Bridges, dams, power plants, and water treatment facilities are all great examples of critical infrastructure that relies heavily on concrete. Not to mention the importance of concrete when building anything below grade from transit systems to parking structures. We need concrete, just not in its current form.
So what makes concrete so bad anyways? It’s mostly the cement, although there are some other contributors as well. One of the best explanations of the problem with concrete is given by the Girl Scouts! If you don’t understand what the hype with concrete is all about, take a look!
As an architect, I was trained to love concrete. Great architects like Tadao Ando (one of my favorites) use almost exclusively the material to express their ideas. It gives almost endless opportunities, will last virtually forever if designed well, and has such raw beauty. We are in love with concrete, but that needs to change.
THE GRAPHIC
The stronger the concrete, the more Global Warming Potential. The more SCM’s (optimized) the less GWP.
WHY IT MATTERS
Concrete matters for three primary reasons:
Not all concrete is the same - pick wisely
Concrete is essential, but use it sparingly
There is hope for a better day
Let’s dig a little deeper:
1 - Not all concrete is the same - pick wisely
The graphic suggests this idea, but concrete is no different than other materials. What you specify can greatly change the impact on the environment. That’s why you need to consider a few things when choosing what type of concrete you decide to use. Here are a few things to consider:
Cement is the biggest problem, more SCM’s will reduce the impact
Concrete is heavy, less travel distance and pumping will reduce
Concrete strength greatly impacts cement amount. Optimize.
Cement replacements like Limestone can have significant improvement
2 - Concrete is essential, but use it sparingly
Architects LOVE concrete. We’ll build entire buildings out of the stuff if our clients let us. This comes from years of education and magazines filled with glorifying images. But - we need to use less so let’s work on that. Ask yourself - is their a less harmful material I could use for this? Does it need to be this big? Can I optimize this design and reduce it? A few ideas to consider:
3 - There is hope for a better day
Since concrete is such a problem it’s getting alot of attention … which is a good thing! There are companies like Blue Planet & CarbonCure who are working to reduce the impact of concrete. There are also projects that produce heat-free concrete which has 90% fewer emissions than typical concrete. There are is also an interesting company called CarbiCrete that produces carbon-negative CMU blocks. There are great minds at work on the problem, but we need more of us focused on the issue from all different angles.
1 TIP - HOW TO REDUCE
The best way to reduce your impact from carbon is through your design and specifications. Make sure your design is optimized to limit the amount of concrete and it’s impact. The second thing to do is to make sure your concrete mix has the highest SCM’s that it can handle. Work with your structural engineer and concrete supplier to ensure this is the case on-site.
1 RESOURCE - TO HELP YOU ACT
The first step is understanding the problem:
Check out the Girl Scouts explain the problem with concrete
The second step is learning how to fix it: