Sustainable Building Materials – The UMass AGC Student Chapter

By Nate Wright
March 1, 2022

Hey everyone. I wrote this post over a year ago over winter break when I become very interested in sustainable building practices and green buildings. After becoming more aware of humans’ negative impact on the Earth and its ecosystems, I just don’t see any reason to NOT strive for the best, environmentally-friendly buildings and projects. The reality is that human construction, waste, and pollution have degraded the planet for decades. Human-made buildings and products should not just co-exist with the environment, but improve it and sustain it. So here’s some information I’ve learned about building materials and why they might be better.

First, let’s talk about concrete, which is the most commonly used man-made material in the world. It’s used in driveways, sidewalks, roads, bridges, airports, foundations, and many other structures. Concrete is so common for several reasons: it is strong, its strength increases over time, it is resistant to weather, fire, mildew, and rotting, it is affordable, it can be shaped easily by pouring it into a mold, and it doesn’t release any known harmful compounds into the air. Despite these benefits, I see two BIG downsides:

How Concrete is Created
Cement, the glue that holds concrete together, is formed by burning limestone and other materials at a high temperature. A byproduct of this process is carbon dioxide, which makes up the vast majority of greenhouse gases. One ton of concrete produces one ton of CO₂, and three trillion liters of water are used per year to make concrete.

Concrete is Unappealing
Concrete is unnatural; it is grey, plain, dull, unimaginative, and completely uniform in color and texture. Can you name one thing in nature like that? Rocks are grey, but their bumps, edges, and variety in shape and size give them character. Concrete on the other hand is not, and when there is a lot of it in one area, it can negatively impact your mood (and therefore your health), whether you are aware of it or not. As humans, we are meant to be in nature, surrounded by it, celebrating it, and working with it.

Research shows that being in nature benefits your overall health drastically (see “Further Reading & Viewing”). Does walking by concrete spark any joy in you? Do you really enjoy it? For the UMass folks, what makes you happier, looking at the Olver Design Building, or the Fine Arts Center? For me, the Design Building excites and inspires me. It feels fresh. I know the Design Building was built more recently, but notice it next time you’re walking near anything. How does it make you feel? Also, notice how you feel when you walk through the Durfee Conservatory… (!)

Alternative Materials, Why They Could Be More Sustainable, and Their Drawbacks

Not only may these materials be more sustainable in terms of cost, resources, and impact on the environment, but they just create a better atmosphere than concrete.

Wood

Being natural and renewable, wood is a great building material. It doesn’t oxidize (no rust), it has great acoustics, and absorbs sound well.

The specific heat of wood is nearly twice that of concrete and three times that of steel, which means it has a higher heat insulation capacity.

Being organic, however, wood is subject to shrinkage, swelling, deterioration, fungi and bacteria growth, and insects. To prevent this and the fire hazards associated with wood, the wood needs to be treated in some way for it to be safe.

Using wood means we need to plant trees as we cut them down. This would require extra efforts to ensure that trees are being planted as they are cut down.
Bamboo (the cheap man’s timber)

It’s cheap, strong, and grows crazy fast (some species can reach full maturity in 90 days, others in just a few years). Bamboo is also earthquake-resistant due to its light and elastic nature, and requires 1/50th the energy for processing in comparison to steel, and is just as strong as wood.

Bamboo becomes soft when heated and can become unstable. To avoid this, bamboo would require treatment (apply a lighter color as darker colors soften quicker). It is also subject to deterioration.

Bamboo can be 20% cheaper than wood, but if bamboo is not grown in the country where it’s being used, the shipping costs can even out that difference or even make it more expensive. It’s also important to keep in mind that governments have yet to set national standards for bamboo structures, and that the shipping charges to non bamboo growing nations can be quite extensive, making it more expensive than hardwood flooring.

Ferrock

Ferrock is a strong and flexible building material that is 95% composed of recycled materials (i.e. steel dust from the steel industry). When curing, it absorbs and traps CO₂ ? about 10% by weight. Being made from recycled materials, it is much “greener” than concrete.

Similar to many of the other materials in this list, ferrock can be expensive and hard to come by only because it is not widely produced. If we transitioned to using ferrock, the costs would certainly decline, but for now we are just really good at making concrete.

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Rammed Earth

This one might be my favorite. It’s so cool. As the name implies, rammed earth is dirt that has been packed together firmly. Thus, it requires no other resources and is completely biodegradable (can it even biodegrade if it’s already Earth?). Check out one way it’s made below.

Long before concrete and other commercial building materials were conceived, humans used the concept of rammed earth to build structures. Parts of the Great Wall of China (built 221 B.C.) are made from rammed earth, and it’s still standing. Some of the benefits of rammed earth, according to an Australian company Rammed Earth Construction, are “temperature and noise control, strength and durability, low maintenance, fireproofing, load-bearing and pest deterrence, as well as its beauty and the pleasure of building with natural and environmentally sound material.” Rammed earth costs are low, are highly available, and can be sourced locally, reducing transportation costs and pollution. On the down side, careful design is needed to direct water away from the walls, and it can be a poor insulator, meaning that it is often insulated with plastic foams, which have very high embodied carbon. However, new insulators made from wood fiber and even mushrooms have far smaller footprints than foam.

Solidia Concrete

In a TED Talk, Tom Schuler of Solidia Tech talks about how Solidia’s concrete is actually carbon-negative, as it sequesters carbon in its hardening process. Solidia’s technology has the potential to eliminate a minimum of 1.5 gigatonnes of CO₂ per year! See the image below for how it is both similar and different to Portland cement concrete. It’s fascinating that it uses the same raw materials but has a significantly lower carbon footprint! This could be a great option as we would not need to replace pre-existing equipment.

Seen above, Solidia cement doesn’t require water. If we transitioned to this technology, we would cut out the three trillion liters of water used per year to make concrete, and simultaneously reduce concrete’s carbon footprint by 70%. Also, fun fact: for a 1km long road section, Solidia concrete captures the same amount of carbon that 100,000 trees do in a year. Wild!

As mentioned before, concrete is the most commonly used man-made material on the planet. The concrete industry has been around for centuries and has evolved very little. Creating change in an industry so massive and with such history may be difficult, but it starts with a reason to change and gradual process over time. (And to be clear: I’m not envisioning a world completely rid of concrete. While desirable for some, that’s just not realistic). Overall, the Solidia Tech concrete seems to offer the quickest and smoothest transition to a more environmentally-friendly alternative to regular concrete. However, we don’t want all of our buildings, bridges, and roads to look the same, so the other materials mentioned above may offer some good variety. And if we do indeed move toward these more sustainable options, they will become more feasible and cheaper to produce.

Related: my good friend Andy Robie (sup Robie!) told me about Earthship homes. They’re sustainable, self-sufficient homes that use zero fossil fuels. Some goals of Earthships are to reduce barriers (economical, institutional, physical) between humans and their habitat and to reduce the overall negative impact that human housing has on the planet. They’re really cool in my opinion. If they sound interesting to you I highly recommend checking out their websites earthshipbiotecture.com or earthshipglobal.com to learn more about how they work.

If you know of other cool stuff like this, or want to drop some knowledge about sustainable construction or materials, leave a comment below! I’d love to hear other people’s thoughts.