Sustainability with Largest Green Roof in Southeast

Photo Credit: Aerial Innovations of TN

By Big River Industries, Inc.

In May of 2013, a 2.1 million square foot building opened in the heart of Nashville, TN with some of the most impressive sustainable features in the region. It was designed and constructed with energy and water conservation in mind, and has been certified Silver Level LEED – Leadership in Energy and Environmental Design – by the U.S. Green Building Council. Of its exemplary high performance features in this building, the most notable is the 175,000 square foot green roof.

The 4-acre green roof was designed to mimick the rolling hills of Tennessee and is currently the largest in the Southeast. It was specifically designed to not only reduce energy usage by absorbing heat and acting as an insulator, but also to combat stormwater runoff by retaining much of the water within it’s soil, or as it known within the green roof industry, the Growing Media. With this roof’s wide span and sloping pitch, it was crucial that the media in the project be extra light and work within a shallow profile.

Working with a certified blending facility, a special growth media was designed using calcined clay lightweight aggregate (LWA) and varying organic components. It was imperative that the LWA be strong, physically stable, durable and light in weight. The LWA is all-natural, eco-friendly and a nondegradable soil enhancer.

The LWA is made by calcining clay at temperatures in excess of 2000 degrees Fahrenheit. The aggregate has a high water absorption rate, is environmentally inert and a generally neutral pH. LWA is ideal for green roof applications, as it helps neutralize acid rain runoff and maintain pH levels in the growing media.

The city of Nashville, TN hosted the 12th annual Cities Alive Green Roof & Wall Conference from November 12-15, 2014.

For more information on green roofs, please visit