Most of us tend to think that “bio-based” materials must be inherently green. However, in an article recently published in Environmental Building News, editor Jennifer Atlee argues that this isn’t always the case.

The first problem, Atlee says, is that the term “bio-based” is overused and way too general. “The green building industry has tended to lump anything with a biological component into a ‘bio-based’ category and pat itself on the back for moving away from fossil fuels,” she says. “Simply switching from the typical nonrenewable feedstock to a renewable one has immediate environmental benefits for some materials, but for others the impact of the material’s biological source on the product is dwarfed by impacts from manufacturing or other stages of the product’s life.”

For example, Atlee says that using corn as a feedstock for plastics (as opposed to fossil fuels) can have huge environmental burdens, as growing corn can result in soil erosion, nutrient runoff, and the use of pesticides, water, and energy.

Another issue, Atlee notes, is that renewable materials often tend to come with a high price. “In order to invest in alternatives, manufacturers have to see clear demand,” Atlee writes. “The market isn’t yet seeing the kind of investment from purchasers on responsible sourcing that is needed to get the attention of larger producers.”

Atlee describes the environmental impacts of several bio-based textiles and biopolymers. Wool, for example, is naturally fire retardant and has great performance results, but the traditional method of scouring and then descaling raw wool uses large amounts of water and hazardous chemicals.

Atlee also examines key sourcing considerations, including certifications and life-cycle assessments. “When comparing bio-based and fossil-fuel-sourced materials, a cradle-to-gate study may make bio-based material look better than is accurate,” she says. “Plants do store carbon, but the terms ‘carbon neutral’ and ‘carbon negative’ neglect that products may also release carbon at end of life.”

In the end, Atlee contends that bio-based materials hold great promise, but there are no guarantees that being bio-based makes them safer or more environmentally friendly than their nonrenewable counterparts. “We need to scrutinize such products carefully, particularly as we create incentives to encourage their further development,” she says.

The entire article, “Biobased Materials: Not Always Greener,” is available by subscription at www.buildinggreen.com and can be used toward continuing education credits.