Meg White is the former managing editor of REALTOR® Magazine.
It’s tough to sell a green roof when you don’t have the numbers to back up its energy-savings performance. This free online calculator allows you to compare the costs associated with traditional roofs with those of a green roof. Developed jointly by researchers at Portland State University, the University of Toronto, and Green Roofs for Healthy Cities, the tool takes into account whether you’re looking at new construction or old and commercial versus residential property. Since you’re providing the building’s location, it also calculates average temperature and rainfall to get a more accurate picture. The calculator even allows you to enter your most up-to-date utility rates, in case your bills have changed a significant amount since their 2010 baseline. The results include electrical and gas savings by volume and dollar. Free. Green Roofs for Healthy Cities, Toronto [realtorm.ag/GreenCalc]