There's no shortage of approaches for a design team to take these days to create structures that are “green.” Yet clarity has been elusive about just what constitutes green and how to measure the “greenness” of a project. The Green Building Initiative is hoping to provide some lucidity to the green design and construction industry through its Green Globes rating system.
|The EcoCalculator evaluates the life cycle assessment of more than 400 common building assemblies based on a number of factors, including resource extraction and processing, product manufacturing, on-site construction of assemblies, and transportation to landfill.|
T here's no shortage of approaches for a design team to take these days to create structures that are “green.” Yet clarity has been elusive about just what constitutes green and how to measure the “greenness” of a project.
The Green Building Initiative is hoping to provide some lucidity to the green design and construction industry through its Green Globes rating system. Most notable is a software tool within Green Globes for evaluating the life cycle assessment of more than 400 common building assemblies. Each of the building assemblies has been evaluated based on:
Resource extraction and processing
On-site construction of assemblies
All related transportation, maintenance, and replacement cycles over an assumed building service life
Structural system demolition
Transportation to landfill.
To ensure fair comparisons between assemblies, the following assumptions were made:
Results are presented on a per-unit-area basis, but the estimator software actually took into account much larger quantities, such as 1,000 linear feet of wall.
Installation for all assemblies was assumed to utilize components and loadings typical for central areas of the U.S.
All assemblies would be used in owner-occupied office buildings with a 60-year lifespan—which affects the maintenance and repair/replacement schedules of relevant building envelope materials (e.g., roofing membranes, cladding systems, and windows).
Other specific assumptions cover factors such as window-to-wall ratio, concrete strength and fly-ash content, gypsum board type, and thickness of latex paint.
The development of EcoCalculator can be traced back to 1991 with an effort funded by the Canadian government. It put in place the Green Plan to start funding research in environmental issues. At the same time, a wood-affiliated group wanted to look at the life cycle of wood versus concrete and steel.
Merging the efforts, the Green Plan created a research alliance that was to come up with answers. Joined for the effort were a major integrated steel company, an arm of the federal government that worked with concrete and steel products, an environmental research group at the University of Vancouver, and others in academia.
“The data work we did then was quite well recognized, so the architectural community said, 'We want more than just these structural products, such as brick and glass,'” says Wayne Trusty, president of the Athena Institute and past manager of the Green Plan.
Six years later, another milestone occurred when the Athena Sustainable Materials Institute was formed in Canada. It acquired the intellectual property of the Green Plan, including reports and databases. Over the next five years, Athena evolved the data from a spreadsheet to an actual software tool, known as the Impact Estimator. Further evolution changed the Impact Estimator to the EcoCalculator.
Since its commercial release in 2003, the EcoCalculator has gone through a number of iterations and has been adopted by several universities, including the University of Minnesota, Arizona State, Harvard, MIT, and Stanford, as well as a handful of large architecture firms.
The recent push to use the tool in the U.S. began in 2004, when USGBC manufacturer members requested that life cycle assessment be integrated into the LEED system. In January 2007, USGBC approved the recommendation for the process.
“With pressure to level the playing field on different products, life cycle assessment is a good way to do it,” says Trusty.
Currently, life cycle assessment is being carefully examined under the Green Build Initiative-American National Standards Institute (GBI-ANSI) process. Because of its value as an indicator of climate change impacts, the GBI also supports Athena's creation of a generic version of EcoCalculator for use by the entire sustainable design community. To create a free EcoCalculator, the rating system-related components have been removed. (The version in Green Globes has weighting and scoring.)
“We left the assemblies with the impact measures so that anybody can go in and see the relative value of using one assembly versus another from an environmental point of view,” says Trusty. He adds that once the GBI-ANSI process is complete, users will see the same assemblies and measurements, but with the addition of a weighting system with points assigned.
Designed for ease of use, EcoCalculator lets you select an assembly sheet from a category such as exterior walls, interior walls, roofs, windows, intermediate floors, and columns and beams. The number of assemblies in each category varies depending on the possible combinations of layers and materials. Assemblies are assessed in terms of a range of performance measures, including global warming potential, embodied primary energy (fossil fuel depletion), pollution to air and water, and weighted resource use.