Primer

Life-Cycle Assessment: Tracing a Product's Impacts

Life-cycle assessment-accounting for all of the environmental impacts of a product from its manufacture to its disposal-is a simple concept, but using it to compare products in practice can be difficult.

If you wanted to know about all the environmental impacts of a product, common sense suggests that you would have to trace that product from the origins of its raw materials, through its manufacture and use, and finally to its fate at the end of its useful life. That’s the premise behind environmental life-cycle assessment (LCA)—a science that aims to quantify all the impacts of a product or service. LCA is often used by manufacturers to compare alternative ingredients and processes for making a product, and by policymakers for establishing preferences for one product over another. When the Coca-Cola Company evaluated whether to switch from glass to plastic soda bottles in the 1970s, its consultants pioneered the use of LCA. (LCA is not the same as life-cycle costing, which looks only at the financial cost of buying, using, and disposing of a product.)

The basic concept is simple, but LCA isn’t easy to do well. First, LCA practitioners have to divide the life cycle of a product into discrete steps so they can measure or estimate the inputs and outputs of each step. Inputs typically consist of raw materials, energy, and water, and outputs include the product itself along with any byproducts and waste products in the form of solid waste, air emissions, and water pollutants. The inputs and outputs of all the steps are combined into a life-cycle inventory that lists every relevant substance and how much of it was consumed or released.

Published May 29, 2008