Gray and durable, concrete has been a literal building block in our homes, bridges, sidewalks and apartments for years. Unfortunately, the process involved in creating this critical building element contributes to our environmental crisis by releasing immense amounts of carbon dioxide into the air. Climate change and our elevated sense of doing what’s right for the environment have led us to find alternative materials to reduce our reliance on concrete. The one you choose will depend on your building needs and goals for going green.
The straw in these bales are made from the stalks of various grains which are cut and baled after the grain is harvested. Farmers are able to make money from what would otherwise be a waste product. Straw bales have insulation values as high as R-30, and can be even higher the thicker the bale. Although construction with straw bales isn’t difficult, it’s best to consult with someone experienced in this style of construction as it involves techniques not used in conventional building.
It may seem too good to be true to find a material that’s good for the environment, fairly easy to construct, and energy efficient. As expected, it has its downsides. First and foremost is that not all locations will allow builds of this type, so be sure to check with your local authorities before making this choice. Also, straw bales do not like moisture, so building with this material is limited to areas that don’t experience much humidity or wet weather. And if you don't live close to the source, shipping expenses and the pollution involved in shipping those materials to your location should be part of your decision.
Grasscrete is a building alternative that can be used in highly trafficked locations like sidewalks and driveways where sturdy support is a requirement. The product is permeable, and though it is created with concrete, the molds have open voids where grass or other plants can grow. These open spaces improve drainage of water that would otherwise flow into storm drains, and give you less concrete to add to your landscape.
Wood and Bamboo
Like hemp, bamboo is a fast-growing resource. Among its many advantages, it's relatively inexpensive, strong, and sustainable, if harvested correctly. It's also a gorgeous building material, with the potential to create lyrical, harmonious structures. One valuable characteristic of bamboo is its tensile strength which refers to the maximum stress it can withstand before it breaks. This makes it an earthquake friendly building material. Processing bamboo for construction requires much less energy than steel, enabling it to be up to 20 percent cheaper than a traditional home. Unfortunately, it's not all good. Formaldehyde, a carcinogen which can cause eye, nose and throat irritation, is often used in bamboo flooring, and harvesting has led to deforestation.
Unlike hemp and bamboo, trees are not fast-growing, but there are still advantages over concrete. During its lengthy growth process, trees absorb carbon dioxide and release oxygen to improve the air. Proper forest management is critical in ensuring access to this valuable renewable resource.
A build of this type is often seen in Earthship construction where soil is packed into tires that form the walls of the structure. Modern rammed earth buildings often use wooden forms that create stylish buildings with enough thermal mass to absorb heat. Specialized machinery packs the earth into the forms, sparing you from straining your back, while rebar or bamboo provide reinforcement for walls.
Expense can be a drawback for a build of this type. Because of specialized machinery and added labor, a rammed earth house can be up to 15 percent higher than a traditional home. Insulation is poor in these buildings, making it an added expense if you live in an area of extreme heat or cold. And though you'd think it would be simply a matter of digging up soil in your area near the building site for the rammed earth, the type of soil may need to be adjusted if it's not composed of a suitable aggregate mix--which may be fine if you aren’t interested in digging large holes in your property. Finally, the forms used are difficult to fill and pack, which means curves can’t be accommodated, giving these buildings a boxy look to them.
Hemp is a fast-growing, pest resistant resource, sturdy, yet lightweight. Because it’s lightweight, it doesn’t require as much energy to transport. Unfortunately, it isn't widely used since not many builders are familiar it, nor its advantages in construction. Despite hemp's many uses, it’s also a heavy feeder and regularly needs large amounts of fertilizer for good growth. Not a good option for someone striving to reduce their negative impact on the environment. And it’s not cheap, so factor in an additional eight to twelve percent in cost when considering this material.
These have made their way into many common construction materials such as roofing tiles, indoor insulation, structural lumber, floor tiles, and concrete, to name a few. Researchers are making strides in making concrete based building materials that incorporate recycled plastic, keeping them out of landfills and reducing greenhouse emissions.
It sounds like a futuristic space term, but if you remember high school biology (we know some of you are out there), you may have heard it before. It refers to the network of fine white filamented root structure of fungi. These filaments grow around materials like ground up straw placed inside forms, creating a lightweight brick or other shape once it’s air dried. They can also be grown in more elaborate shapes, creating gorgeous, organic structures of all sizes.
Another product that utilizes waste material, ferrock gives new life to steel dust produced during the steel making process. The resulting material is even stronger than concrete, and even more incredible--it absorbs CO2 during the drying process
That’s ashcrete and timbercrete. Made from—you guessed it—ash (for ashcrete) and corresponding timber. The ash and timber are waste products that would otherwise go unused, but have been formulated into building materials that are lighter than traditional concrete, and less destructive on the environment.
There are many alternatives to building your green dream home. Continued research will certainly unfurl more choices for the savvy eco-warrior.