Compare the cost of green roofing with conventional roofing systems! Interested in green roofing but not sure how to determine its long-term costs and benefits, especially compared to traditional roofs? Stop wondering. Green Roofs for Healthy Cities (GRHC) with support from Tremco Roofing and Building Maintenance and the Athena Institute, are proud to bring you the GreenSave Calculator, specifically designed to help professionals concerned with sustainability. The GreenSave Calculator was developed by GRHC and the Athena Institute with funding by Tremco.