At November’s Greenbuild show in Phoenix, I attended a session where researchers from the University of Tennessee discussed their life-cycle assessment (LCA) of different cladding materials.
The researchers used two different assessment tools: the Athena Institute’s EcoCalculator and the BEES (Building for Environmental and Economic Sustainability) 4.0 program, developed by the National Institute of Standards and Technology.
The results? Wildly different – the programs varied by a factor of more than 70 percent in assigning final environmental impact scores to stone, aluminum, and glass façades.
LCA is a complex business. It attempts to benchmark a construction product through the circle of raw material acquisition, manufacture, transportation, installation, use, maintenance, disposal, and recycling. Some LCA tools also provide a rating for economic performance by considering the costs of initial investment, replacement, operation, maintenance, repair, and disposal. At every step of the way, bundles of assumptions are made that affect the outcome, which is a numerical rating.
Of course, the authority and persuasive power of numbers can fool us into thinking that they’re final and objective. Or, for the sake of convenience when making a difficult decision, we accept a number as the final say. As that flinty journalist H.L. Mencken said, “For every complex problem, there is a solution that is simple, neat, and wrong.”
LCA is in its early stages. As manufacturers increasingly use various methods for qualifying their green building products, a welter of conflicting numbers will be tossed around. In time, LCA tools will be refined to yield more congruent ratings. In the meantime, the situation may remind us of Mark Twain’s complaint: “There are three kinds of lies: lies, damned lies, and statistics.”
But taking the long view – which is what LCA is all about – is good for business in the long run.
