Sorting it all out

With all these options, it's a daunting task to compare environmental impact of the various rapidly renewable materials with each other, let alone with competing conventional products. Owens explains that questions about where a material comes from, how it's used, how long it will last, and whether it has recycled content are "single-issue proxies for life-cycle-assessment-based thinking." Life-cycle assessment, or LCA, is a methodology that quantifies the environmental impact of a material by examining how it is grown, harvested, transported, maintained, and eventually disposed of, computing costs in energy and water use, air degradation, and other factors. The USGBC Materials and Resources Technical Advisory Group is grappling with the best way to incorporate what Owens calls "multi-attribute life-cycle screening" into LEED.

Oak Lodge (top), a Jesuit retreat in California's Sierra Foothills designed by Siegel & Strain Architects, has walls of highly insulating straw bales covered by stucco. Details for incorporating the straw bale into standard construction (below) are evolving. Photo © J.D. Peterson.

 

However, life-cycle assessment has its shortcomings, according to some sources. Although the methodology can provide a more standardized way of comparing diverse material options, different analyses might use different data sets, leading researchers to completely different conclusions, says New York City−based Cynthia Tyler, senior research scientist at Material ConneXion, an information source for innovative materials. In addition, an LCA typically considers no options besides disposal at the end of a material's useful life. This "cradle-to-grave" analysis will essentially tell you only which option is less detrimental, she says.