Selecting materials for your green building project can be daunting, to say the least. Every product says it is “green” or “environmentally friendly.” In addition, there are different certifications and labels, each supposedly better than the others. Many green guides and books have been written to try to dispel the myths and break through the “greenwashing.” It is enough to make a person’s head spin!
Natural Materials – From Nature
One seemingly obvious alternative is to buy products taken directly from nature. Wood, linoleum, bamboo, wool carpets, cork, and wheatboard are a few that come to mind. Most of these materials are available at mainstream hardware stores and through traditional interior decorators. We will look at the environmental characteristics of each, and what makes them “green.”
Wood
Wood comes from trees, and is therefore a natural material. Wood harvested from traditional forests is harvested when the trees are mature. How long trees take to reach maturity varies by species and variety. Forest trees grow without assistance from man or any man-made substances.
When trees are harvested, there is an environmental impact from the logging activities, including building roads, running saws, lifts, and log trucks to take the wood to the mill. Once processed, there are further impacts from transporting the wood to the stores where it is sold. There is also a loss in oxygen production when trees are harvested and not replaced.
Raw wood doesn’t have any added toxins or chemicals, and is safe to handle and install indoors. Engineered wood products, such as trusses or joists, and particleboard, like plywood or OSB (oriented strand board), are usually held together with some form of adhesive.
Most adhesives will contain added chemicals, like urea formaldehyde, that can off-gas into the interior of a building, causing respiratory irritation at the very least. Recently, however, manufacturers have started using adhesives without these chemicals in their wood products. Be aware of the contents of the adhesives in the wood products you purchase.
Adding finishes, like paints or stains, will also add chemicals to the wood. Look for coatings with low VOC (volatile organic compound) levels, or use natural finishes such as Osmo, a blend of natural oils and waxes.
Linoleum
Made up of linseed oil, jute, pine rosin, wood flour, and calcium carbonate, linoleum is a natural and renewable 
building material. Invented in the mid 1850s, it has stood the test of time. Originally it was only available in large sheets, like carpet, but now can be found in tile form, too.
Natural linoleum has been largely replaced by vinyl flooring or tiles, some of which are marketed as linoleum. Buyers should be careful when selecting linoleum to insure that they are receiving the right product. Forbo Marmoleum is the number one brand of linoleum world-wide.
Bamboo
A plant that most people fight to get rid of can provide a beautiful finish for wood floors, cabinets, and other trim materials. Bamboo grows very rapidly and can be harvested repeatedly during a plant’s lifetime. The shoots are cut, boiled in boric acid or lime, and laid flat to dry. Then they are planed to a smooth finish.
Flooring made of bamboo has a look similar to hardwood. It is as durable as hardwood, and can be sanded and finished in a similar way. Bamboo plants take only seven years to reach maturity, significantly less than their traditional hardwood cousins.
The species of bamboo used for most flooring, Moso, is most readily available in China, so there is a lot of transportation involved in getting the product to the U.S. or other countries.
Wool Carpet
Wool not only is a natural product, coming from sheep, of course, but it is also renewable, in that the sheep continually grow more wool. This makes it a naturally sustainable material. The wool for most carpet comes from New Zealand, so transportation impacts can be high.
Backing materials for carpet are not always as sustainable, unfortunately. Most are made from petroleum products or PVC, which can give off some nasty chemicals during manufacturing, installation, and during its useful life. Many carpet manufacturers, such as Interface, are changing the way they produce carpet to make it more sustainable, and are reducing the chemicals in their products. Carpets certified by the Carpet and Rug Institute’s Green Label and Green Label Plus programs have been independently tested for chemical off-gassing.
Cork
Cork is a rather interesting material, as it is actually the outer layer of bark on a tree. It is harvested by cutting off this outer layer, leaving the inner layer of the cork tree exposed. The cork bark then grows back and can be harvested again. Most trees can be harvested about seven times in their lifetime.
It makes an excellent flooring material, as it is both rigid and soft, and naturally antimicrobial. Like a hardwood floor, it can be sanded and refinished. Care needs to be taken when placing furniture or other heavy items on it, as they will make indentations in the floor. Pads to disperse the weight are suggested.
The cork used for flooring comes from India, so there will be environmental impacts caused by transportation.
Wheatboard
Made from the leftover stalks of harvested wheat, wheatboard is a type of particleboard made to substitute for MDF (medium density fiberboard) or other particleboards. It’s most common use is in cabinets, where it is used to form the boxes. Not only is it made from a waste product, but when combined with a urea formaldehyde-free adhesive, it contains no toxins to off-gas into a building.
There are lots of choices for natural building materials, even more than I have listed here. The key is to research the options carefully, and verify with the manufacturer that you are getting what you want. Next week, we will continue our series by taking a look at natural building materials su
Editor’s Note: Dawn Killough is a LEED Accredited Professional working with sustainable materials on daily basis.
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Photos courtesy of: kevmann16, Forbo, ecvv.com, and Dag Endresen.
We have an actual list of materials, graded for sustainability, on our site, Smart Energy.