The Center for Sustainable Building Research at the University of Minnesota and the Athena Sustainable Materials Institute have released a report, “Life Cycle Assessment of North American Residential and Commercial Windows: Life Cycle Goal and Scope Specification,” which they say is focused on providing a standardized, accurate and representative environmental life cycle assessment (LCA) of commercial and residential windows. The recently released goal and scope were prepared to serve as a precursor to a full “cradle-to-grave” LCA study of commercial and residential windows, which, once completed, will serve as a roadmap for collecting, compiling and interpreting that data. The report notes that the goal and scope were commissioned by the Department of Energy, and the LCA will be commissioned by other U.S. government departments as well as a number of industry organizations, including the American Architectural Manufacturers Association (AAMA), the Glass Association of North America (GANA) and the Insulating Glass Manufacturers Alliance.

Jeff Inks, vice president, code and regulatory affairs for the Window and Door Manufacturers Association (WDMA) says his group is also considering levels of funding for the program.

“Because LCA is growing in importance as criteria for energy-efficient and green building programs and now new green building codes and standards, we are very interested in this work,” says Inks.

“Many component manufacturers have been scrambling to assess and prove their green credentials and how they can help designers and owners accumulate points in the various green building rating systems,” says Rich Walker, AAMA president and chief executive officer. “These rating systems go beyond energy efficiency to address a much wider range of concerns involving site use and occupant wellbeing. LCA is considered the scientific way to assess the overall environmental impact of materials, products, and building assemblies. LCA is a systematic, cradle-to-grave evaluation from resource extraction and embodied energy (energy used in the production of the product) through to disposal.”

Bill Yanek, executive vice president for GANA, says the association and its membership believe that in energy-efficiency debates, too often, emphasis is placed upon the energy intensity of the glass manufacturing process.

“The energy saving and energy producing aspects of value-added glass products and clean energy using glass should be part of the debate. A thorough life cycle analysis will provide a more complete picture of the role of glass in energy efficiency,” said Yanek. The proposed study is based on case studies and will review more than 150 window variations. It is also expected to result in a modular database through which additional window permutations and combinations may be assessed.

The report notes that case studies for the commercial functional unit will include 1500-mm x 2500-mm (fixed), 900-mm x 1500-mm (casement) and 1500-mm x 2500-mm (curtainwall) windows installed in a high-rise office building for 73 years, modeled in six climates; double- and triple-glazed produced with sputter-coat and hard-coat low-E glass, all with air fill and aluminum spacers; and frames made of fiberglass and aluminum.

For the residential functional unit they will include 1000-mm x 1600-mm (double hung) and 1200-mm x 1200-mm (fixed) windows installed in a single-family house for 85 years, modeled in six climates; double- and tripled-glazed, produced with sputter coat and hard-coat low-E glass, all with argon fill, dual-compound sealant and aluminum spacers; and vinyl, aluminum clad wood, and vinyl clad wood.

Researchers say that the results of the LCA may be incorporated into programs such as Energy Star® and also included in various software and calculation tools. They add that the methodology, results and interpretation of the LCA study will be subjected to concurrent critical review to ensure the project is consistent with ISO 14040 standards.