Illustration by Lil Chan
Green roofs offer significant environmental advantages, thanks to the vegetation, drainage and irrigation they provide. They do a great job of soaking up stormwater to prevent flooding and water pollution. They moderate the temperature of the buildings below, reducing energy costs. They break up heat islands in massive areas of concrete and asphalt in cities. They even provide habitat for birds and pollinators.
However, green roofs have a major disadvantage: their initial cost is much higher than that of traditional roofs. That extra cost can cause municipal governments, universities and developers to avoid building them.
Some cities have found a way to justify this higher cost: design the green roof alongside another significant public benefit.
An excellent example of this trend in green roof construction is Columbus Commons in downtown Columbus, Ohio, completed in 2012. This $20 million project features an underground parking garage whose green roof is part of a roughly six-acre public park with amenities and open green space.
The project’s developers, the Downtown Development Corp. (CDDC) and Capitol South Community Urban Redevelopment Corp. (Capitol South), are each private non-profit development organizations. The Georgetown Co. served as development manager. The design/build team included construction manager Corna-Kokosing, architects Moody Nolan and landscape architects EDGE Group.
Once a thriving mall
The site was formerly occupied by the City Cente