"The fundamental metric is tons of CO2. Green Footstep compares your building's CO2 to that of the carbon stored on the building site," including standing timber and plants on site before he development Bendewald explains. "If the cumulative emissions of the building do not equal the site-stored carbon in its native-state (a positive number), then the project is not carbon neutral."

Developers and designers can then use that information to change their buildings to pay off that carbon debt and restore the balance, using such methods by reducing building energy use and/or incorporating more renewable energy. Users can establish free accounts so they can save and reload their projects and track the adjustments.

"Mostly architects," have taken advantage of the program thus far, Bendewald notes. "Building owners, engineers, consultants and educators have also found it useful."

Designers can use the tool to comply with specific design goals such as LEED certification credits and the 2030 Challenge, an organization looking to make all new buildings carbon neutral by 2030. The calculator can help decision-making through pre-design to occupancy on residential and commercial buildings, both ground up and retrofits. More than 250 users have used the tool, including Irving Oil's headquarters in St. John, New Brunswick, Canada, which used the calculator to determine early design targets and will revisit it for later phase verification.

"In a world with ecological limits, Green Footstep interactively helps inform decisions about carbon," said Victor Olgyay, a principal at RMI, in the Green Footstep announcement. "Green Footstep makes it easier for designers to make every building they work on part of the solution to climate change," says Olgyay.