From building green to monitoring carbon footprints, sustainability has become part of doing business for many corporations. These companies no longer look at the growing green trend as an obstacle but as an opportunity to supplement their legacy. The effect on the corporate world is evident, but less obvious is the fact that corporate culture, with its inherent focus on performance, also has begun to influence the sustainability movement in a positive way.

The shift is especially pronounced in the context of green-building rating systems, which in the past have been more prescriptive than performance based. As an example, some rating systems give credit for materials produced within 500 miles (805 km) of the structure being built. This makes sense on an intuitive level because less energy is required to transport the materials. But there are a tremendous number of factors that influence whether a locally produced material actually is better for the environment. These factors include the source of the material’s components, type of manufacturing process and mode of transportation. Using locally produced materials could add to or detract from a building’s sustainability.

Those who want to know for sure, including many of those involved in the development and evolution of green-building rating systems, are placing an increasing emphasis on life-cycle assessment, or LCA. LCA is important to sustainable design because it facilitates impartial comparisons of materials, assemblies and entire buildings. It considers materials during the course of their entire lives, from resource extraction through recycling, reuse or disposal. LCA also takes into account a range of environmental impact indicators, such as embodied energy and global-warming potential.

Instead of rewarding materials or products for specific attributes that are assumed to have environmental benefits, rating systems that incorporate LCA put the emphasis where it should be—on building performance. This gives designers the flexibility to choose how to achieve their environmental goals.


Although LCA is widely recognized as one of the best ways to assess building sustainability, the challenge has been the perception that LCA is too complex and time consuming to be used by the mainstream design community.

To help make it more accessible, the Athena Sustainable Materials Institute, Merrickville, Ontario, Canada, recently released a new spreadsheet tool, the Athena EcoCalculator for Assemblies. It is available free of charge to architects, engineers and others who want to evaluate building designs based on a more complete understanding of total environmental impact.

Developed by the Athena Sustainable Materials Institute in partnership with the University of Minnesota, Minneapolis, and Morrison Hershfield Consulting Engineers, Toronto, the EcoCalculator originally was commissioned by the Portland, Ore.-based Green Building Initiative for use with its Green Globes environmental assessment and rating system for commercial buildings. However, because of its value as an indicator of potential climate change impact, GBI also supported the creation of a generic version that could be used by the entire sustainable-design community.

The EcoCalculator provides instant LCA results for hundreds of common building assemblies, including exterior walls, roofs, intermediate floors, interior walls, windows, and columns and beams. The information embedded in the tool is based on detailed assessments completed with its parent software, the Athena Impact Estimator for Buildings, which in turn uses Athena Sustainable Materials Institute’s own datasets along with data from the U.S. Life Cycle Inventory Database established by the National Renewable Energy Laboratory, Golden, Colo.

Assemblies are evaluated in terms of a range of performance measures, including globalwarming potential, primary energy, fossil-fuel depletion, air and water pollution, and weighted resource use. Results show real-time changes as the inputs are adjusted—a function that allows different assembly options to be considered in light of their environmental impacts.


Because GBI has initiated the process to establish Green Globes as an official standard under the Washington, D.C.-based American National Standards Institute, the LCA tool has been reviewed by the ANSI technical committee in preparation for its integration into the system. To a limited degree, the Green Globes system already incorporates LCA by rewarding its use in material selection.

The hope is that governments, green-building organizations and others will leverage the EcoCalculator for use in their own green-rating systems, programs and policies and that it will help achieve goals related to the reduction of carbondioxide emissions, which are widely accepted as major contributors to global climate change.

While the green-building community has long recognized the value of LCA and encouraged its use, technology is at last making it possible for mainstream design professionals to have streamlined access to crucial data about building assemblies. This technology gives the public and private sectors the information they need to choose materials based not on their perceived effects but on their true performance.

For more information or to download the Athena EcoCalculator for Assemblies, visit the Athena Institute's website at