As part of its mission to drive efficient use of resources, the Rocky Mountain Institute (RMI) in Snowmass, Colo., developed Green Footstep, a carbon calculator that helps building designers, architects, engineers, and contractors adjust designs to lower a project’s carbon footprint.

“It was something we developed out of our work on projects where we were trying to communicate carbon emissions to our clients,” RMI analyst Michael Bendewald says. “We wanted something that was easily accessible online and that provided instantaneous feedback about energy use for design decisions.”

The program is donor-funded, so access is free. It can be used for both new construction and remodeling projects. Users who create accounts can save project specifications on the program.

Users are first asked to define and answer questions about the baseline building, including location, square footage, and energy use by square foot. The program calculates the native-state carbon storage of a site, including standing timber and other vegetation.

Green Footstep then allows designers to adjust design targets, such as building energy-use and inclusion of renewable products, both of which help to move the building closer to carbon neutrality.

For example, Bendewald says, a user can see the energy saved by increasing the roof’s R-value from R-19 to R-40. The program shows how that change affects the carbon footprint.

But to make the calculation, users must first know and enter some energy value information into the program, which can be difficult to calculate for existing homes. (Bendewald says that in commercial construction there are more tools available for figuring out energy values.)

The program also shows designers how to comply with specific goals such as the U.S. Green Building Council’s LEED rating system and the Architecture 2030 initiative.

—Nina Patel, senior editor, REMODELING.