Straight Green: Maximizing Use of Rapidly Renewable, Bio-Based Materials
LEED offers a single point for using rapidly renewable materials with a minimum value of 2.5 percent of all materials used in the building. Use of Bio-Based materials in the Green Globes rating system gives project teams a total of 6 possible points for using anywhere from 1 to 20 percent of materials used in the building.
The LEED rating system effectively removes any wood-based material or product from consideration due to the 10 year harvest cycle requirement. Green Globes recognizes that wood is a renewable resource, and as such should be rewarded for use in a building even if it isn’t rapidly renewable but must also be certified as sustainably harvested to contribute. In both cases, it has been difficult to get the points because so few of the materials used in a building, as a percentage of cost, are rapidly renewable or bio-based. This may soon change because new rapidly renewable/bio-based products have been developed and are now entering the market. In this article, I explore the possibilities of maximizing the potential to acquire these points using a building currently in design at architecture firm I work for.
Squeezing Rapidly Renewable, Bio-Based Materials into a BuildingThe building I am currently working on is a college campus administrative office facility approximately 60,000 square feet with an estimated construction budget of $23 million. The building is being designed to achieve a LEED Platinum rating, with nearly all available points being pursued, including MR Credit 6 - Rapidly Renewable Materials. The first step in tacking this credit is to calculate the required dollar amount needed to get to the 2.5 percent threshold. LEED allows project teams to use a .45 multiplier to come up with a default materials budget cost, which for this project is $10.3 million. To calculate the amount needed for MRc6, this number is multiplied by 2.5 percent, which equals $258,750. This is the minimum that rapidly renewable materials must amount to for the award of the point.
The list of possible materials identified in the LEED rating system reference guide includes bamboo flooring, cotton batt insulation, linoleum flooring, sunflower seed board panels wheatboard cabinetry, wool carpeting and cork flooring. In addition to these materials the project team also found new products like a phenolic resin laminate-faced composite wall panel made with 30 percent bamboo fiber and an acoustical ceiling panel made with 100 percent jute.
The team identified several materials early in the planning process that could be specified toward achievement of this credit, including the following (dollar amount contribution in parentheses):
Linoleum Floor Tile by Forbo Marmoleum ($50,000).
Cotton Batt Insulation by Bonded Logic, Inc. ($18,000).
Bio-Based Acoustical Ceiling Panels by Armstrong World Industries ($45,000).
Earth Door Agri-Fiber Core Flush Wood Doors by Graham Wood Doors ($10,500).
EcoClad Bamboo Fiber Composite Wall Panels by Kliptech Technologies ($9,000).
All added up, the total comes to $132,500-only half way to the mark! With roughly an additional $130,000 to go to achieve the point, it has become cost prohibitive to the project, extremely disappointing considering the teams deliberate approach in selecting materials toward its achieving. Were Green Globes being used as the rating system for the project, the materials selected would have earned the project one of the six available points.
Are Rapidly Renewable, Bio-Based Materials Better for the Environment?When I served on the LEED Materials and Resources Technical Advisory Group, many discussions were had concerning the environmental consequence of favoring rapidly renewable materials over any other. At that time, information available to the group suggested that not all bio-based materials were equal. Bio-based materials originate from things grown and harvested and this process can result in a very large, negative environmental consequence. Add to this the impacts for processing into materials and products, in-service use, and end of life disposal and the footprint gets even bigger.
I was not all that surprised, then, with similar conclusions drawn in a new study “Sustainability Metrics: Life Cycle Assessment and Green Design in Polymers,” which appeared in the publication Environmental Science & Technology, September 2, 2010. The study compares the environmental attributes of 12 polymers, some bio-based, the rest petroleum-based, using Green Design Principles and Life Cycle Assessment. The bio-based polymers are highly ranked using the Green Design Principles due in large part to the fact that the Principles value bio-based content above all other-no surprise here. The same bio-based polymers don’t fare so well, however, when evaluated with Life Cycle Assessment analyses. The study concludes that:
“While biopolymers uniformly rank highly in terms of green design, they exhibit relatively high environmental impacts from production. As shown through the LCA results, biopolymers represent decreases in fossil fuel use and global warming potential and increases in other impact categories such as eutrophication, human health impacts, and eco-toxicity. These impacts result both from fertilizer use, pesticide use, and land use change required for agriculture production as well as from the fermentation and other chemical processing steps.”
The study is interesting, but not all that useful to building practitioners because it does not account for any impacts associated with the use or end-of-life of the materials, significant factors that must be accounted for with regard to building materials, as emphasized in the study with this conclusion:
“… the environmental and human health impact of chemical byproducts of [bio-based] PLA or [bio-based] PHA biodegradation have yet to be studied. The biodegradation of these polymers inherently produce the greenhouse gases carbon dioxide and methane.”
ConclusionMore and more rapidly renewable, bio-based building materials are becoming available and easier to incorporate into buildings. This can make it easier to achieve green building rating system points, but usually at a price. In the example given above, if the client had an unlimited budget, the LEED point for this credit would be easily achievable simply by adding more linoleum, or bamboo flooring, or even using a more expensive line of linoleum or bio-based composite wall panel (the range in price per square foot for these materials can be huge, depending on color, thickness, texture, etc.). Unfortunately, most clients do not have unlimited budgets which means that, even with an abundance of rapidly renewable, bio-based materials available, the available point(s) will remain very expensive to chase.
The very real issue of whether or not maximizing the use of these materials is really better for the environment at all is something that every project team should carefully consider. Doing the right thing from an environmental standpoint does not necessarily include the pursuit of rapidly renewable, bio-based points.