by Margaret Montgomery

One of the most difficult problems for architects interested in sustainable design is knowing which materials are "green." Is the material recycled? Local? Renewable? Is it low in volatile organic compounds (VOCs)? What if you have to choose between these attributes? Are there other factors to be considered? And what about marketing claims? Is a material really "green" just because the manufacturer says it is? The choices can be bewildering.

Sustainable design is necessarily integrated, so making one good material choice will not suffice. And sometimes two good choices can, in combination, add up to a poor choice. For instance, recycled paint from a local source may actually have high-VOC content. One way to understand the complex interaction of factors is through life cycle assessment (LCA). The usefulness of available analysis software depends on your needs and the location of your project.

LCA analyzes the total environmental impact of all materials and energy flows, either as input or output, over the life of a product from raw material to end-of-life disposal or rebirth as a new product. (This is not to be confused with life cycle costing, or LCC, which considers only monetary cost.)

The LCA process is governed under ISO 14000, the series of international standards addressing environmental management. The process requires four general steps: goal and scope definition, inventory analysis, impact analysis, and interpretation and conclusions.

While a detailed analysis for each building material is beyond the capabilities of most architects and building professionals, any LCA analysis tools we use will be built from a database of this kind of information. Building product manufacturers can develop such data with help from software like SimaPro 5.1, GaBi4, and TRACI.   >>>

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Generating reports on emissions from two building products using the Athena life cycle assessment software. Image: Athena Sustainable Materials Institute Initial project screen of the LCA software, Envest. Image: BRE Sustainable Consulting   Click on thumbnail images to view full-size pictures.