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Abstract
When selecting among alternative materials and systems, two methodologies, both scientific approaches, are available to the building envelope designer. Life cycle cost (LCC) evaluates the economic impact of a product throughout its life cycle while life cycle assessment (LCA) evaluates a product over its life cycle. But, LCA target environmental rather than economic impact as the primary measure. Frequently referred to as a “cradle-to-grave” approach, LCA tracks the impact of a product from initial extraction of raw materials to the eventual recycling or disposal of the finished product. The LCA approach is also a key element in the ISO 14000 standards for environmental management; and many global manufacturers now use LCA to evaluate and compare their products against competitive materials. With the 2007 announcement by the U.S. Green Building Council that LCA will be integrated into the Leadership in Energy and Environmental Design (LEED) Green Building Rating System, it is anticipated that all manufacturers of building materials in North America will soon be required to provide product LCA information in order for their materials to be considered for inclusion in LEED projects. Because the materials that make up the building envelope are constantly exposed to harsh weather conditions and are expected to perform without failure for many decades, the construction industry has traditionally relied on LCC, with its emphasis on product durability, as the best measure of long-term value. As the construction industry moves from LCC to LCA, however, some members of the industry are concerned that the new LCA approach may place too little emphasis on product durability. After a brief review of the history of this new approach, this paper discusses the basic concepts of LCA and reviews the relationship between LCA and product durability. Examples of roofing and other building envelope materials that have been analyzed using LCA are reviewed, and the implications of the findings discussed. Finally, the paper offers suggestions for best industry practices in implementing LCA as an integral part of building envelope design.
When selecting among alternative materials and systems, two methodologies, both scientific approaches, are available to the building envelope designer. Life cycle cost (LCC) evaluates the economic impact of a product throughout its life cycle while life cycle assessment (LCA) evaluates a product over its life cycle. But, LCA target environmental rather than economic impact as the primary measure. Frequently referred to as a “cradle-to-grave” approach, LCA tracks the impact of a product from initial extraction of raw materials to the eventual recycling or disposal of the finished product. The LCA approach is also a key element in the ISO 14000 standards for environmental management; and many global manufacturers now use LCA to evaluate and compare their products against competitive materials. With the 2007 announcement by the U.S. Green Building Council that LCA will be integrated into the Leadership in Energy and Environmental Design (LEED) Green Building Rating System, it is anticipated that all manufacturers of building materials in North America will soon be required to provide product LCA information in order for their materials to be considered for inclusion in LEED projects. Because the materials that make up the building envelope are constantly exposed to harsh weather conditions and are expected to perform without failure for many decades, the construction industry has traditionally relied on LCC, with its emphasis on product durability, as the best measure of long-term value. As the construction industry moves from LCC to LCA, however, some members of the industry are concerned that the new LCA approach may place too little emphasis on product durability. After a brief review of the history of this new approach, this paper discusses the basic concepts of LCA and reviews the relationship between LCA and product durability. Examples of roofing and other building envelope materials that have been analyzed using LCA are reviewed, and the implications of the findings discussed. Finally, the paper offers suggestions for best industry practices in implementing LCA as an integral part of building envelope design.
Date
4/2009
4/2009
Author(s)
James Hoff
James Hoff
Page(s)
189-200
189-200
Keyword(s)
life cycle assessment; LCA; building envelope; environment; low slope roofing; LEED;
life cycle assessment; LCA; building envelope; environment; low slope roofing; LEED;