This calculator was developed through a collaboration led by Dr. David Sailor (while he was on the faculty of Portland State University), along with Brad Bass at the University of Toronto, and with input from Steven Peck at Green Roofs for Healthy Cities. The effort was funded by the US Green Building Council with additional financial and in-kind support from University of Toronto, Portland State University, GRHC, and Environment and Climate Change Canada. Ongoing maintenance and support of the calculator is provided by Julie Ann Wrigley Global Institute of Sustainability at Arizona State University.

The green roof energy calculator allows you to compare the annual energy performance of a building with a vegetative green roof to the same building with either a dark roof or a white roof . At the present time simulations are available for new construction (ASHRAE 90.1-2004) and old construction (pre-ASHRAE 90.1-2004) office and residential buildings driven by typical precipitation and weather data. Representation of an irrigation schedule is optional. Read more about how the Calculator works.