Green roofs: not just for looks

This post contributed by Terence Houston, incoming ESA Policy Analyst

What is an innovative method to reduce both heating and cooling in buildings, reduce storm water run-off, preserve natural habitats and even refrigerate warehouse beer? According to scientists at the Ecological Society of America’s 95th Annual Meeting in Pittsburgh: green roofs. These vegetated roofs, as the ecologists explained yesterday in “Rooftop ecology: what is a green roof and why should ecologists care?” provide a wide array of economic, architectural and environmental benefits.

Colleen Butler of Tufts University, and moderator of the session, suggested the use of sedum—flowering plants known for their water-storing leaves—during the talk “Linking the plasticity to success of sedum on a green roof.” Sedum has been cited as one of the most commonly used plants in green roof planning due to its drought tolerance.

Bradley Rowe of Michigan State University answered the question of whether green roofs can sequester carbon with a conditional “yes.” He explained that the efficiency depended on a set of variables, including the amount of biomass as well as the design and length of the individual roof. It was also noted that a large green roof had the capability to help keep the contents in a warehouse up to 30 degrees Celsius below the outside temperature.

Mitchell Pavao-Zuckerman of the University of Arizona highlighted the importance of using indigenous plants in sustaining green roofs that can thrive in semi-arid urban ecosystems such as Tucson, AZ. His research highlighted the ability to sustain green roofs in non-temperate environments.

Many of the speakers agreed that selecting a variety of plant species for green roofs can also help create greater synergy and promote roof longevity. As benefits continue to be discovered, green roofs may play an increasingly integral part in the germination of new ideas and methods to both sustain and improve the quality of our natural, and architectural, surroundings.

Photo credit: TonyTheTiger