Green Footstep is an easy-to-use, detailed, and free online carbon calculator for reducing carbon emissions in building construction and retrofit projects available from Rocky Mountain Institute. While there are many other carbon calculators available online, none address multiple building emissions over the building lifetime. This tool helps building designers assess a project’s carbon emission impacts with regard to site, construction, and operations. Because the 2030 Challenge is integrated into the program, this tool can also help designers in their efforts to meet or exceed those targets. Users can create a login that allows them to save and reload their own projects as they work on them. A great site that will hopefully be put to good use.