Life Cycle Assessment
Life cycle assessments of products typically identify all significant energy and environmental impacts in the course of the product’s manufacture, distribution, use, maintenance and disposal.
Life cycle studies tend to demonstrate that the environmental benefits of a product with a long life can far outweigh the environmental effects of manufacturing the material in the product. For example, studies have shown that the amount of emissions coming from the manufacture of vinyl used in a window is far outweighed by the decades of energy-saving benefits of that vinyl window.
Life cycle studies also challenge pre-conceived notions. For example, a study conducted under the Building for Environment and Economic Sustainability (BEES) program, developed by the U.S. National Institute of Standards and Technology (NIST) with funding from the U.S. Environmental Protection Agency (EPA), compared “natural” linoleum and vinyl composition tile flooring. The study concluded that, when life cycle considerations were “quantified and combined using the EPA importance weights, the net effect is environmental scores slightly favoring vinyl composition tile.”1 This type of analysis affirms the importance of systematic, multidimensional, life cycle studies in determining the true environmental attributes of competing products.
Finally, life cycle studies have an important value in helping manufacturers better understand where they can focus on material or product improvements.
Since the late 1980s, at least 26 life-cycle evaluations have been completed on vinyl building products, many of them comparing vinyl products to similar products made of other materials. Vinyl products generally have been found to perform favorably in terms of energy efficiency, thermal-insulating value, low contribution to greenhouse gases, and product durability, which means using fewer resources.
While LCA studies often do not declare a clear environmental “winner,” they show the trade-offs among materials. For example, a life cycle study by Franklin Associates has shown that vinyl windows require three times less energy to manufacture than aluminum windows.2 The use of vinyl over alternatives in window frames saves the United States nearly two trillion BTUs of energy per year – enough to meet the yearly electrical needs of 20,000 single-family homes. The same study found that manufacturing of vinyl products accounts for less than 0.3 percent of all gas and oil consumption, with windows and doors accounting for a small fraction of that number.
Strong agreement exists today that the principles contained in the International Standards Organization (ISO) 14000 series Environmental Standard (14040–LCA General Purpose, 14041–LCA Inventory Analysis, 14042–LCA Impact Assessment and 14043–Improvement Assessment) provide an effective guide for performing a comprehensive life cycle assessment.
Several computer programs are available that follow the principles of ISO 14000. One is the BEES program mentioned above. It evaluates a product’s environmental performance over the life of a building based on six regional and global impacts: global warming, acidification, nutrification, natural resource depletion, indoor air quality and solid waste. The BEES user may provide a weighted value for each environmental impact category according to a system used by EPA’s Science Advisory Board, a Harvard University study or a set of equal weights.
While LCAs are important tools, they are not perfect. For example, their results depend on the availability, quality and transparency of the underlying data. As time goes on, more organizations are recognizing the need for high-quality life cycle data and are taking the initiative to conduct the necessary research and analysis.
For more information, see the following sources:
International Organization for Standardization:
Building for Environment and Economic Sustainability and the National Institute of Standards and Technology (NIST):
1B.C. Lippiatt, “Economic and Environmental Performance for Tile/Glass, Linoleum and Vinyl Tile Using the BEES Model,” National Institute of Standards and Technology, (1998).
2Comparative Energy Evaluation of Plastic Products and Their Alternatives for the Building and Construction and Transportation Industries,” Franklin Associates, March 1991.