Rice University, TX Green Roofs Policy
Rice's new utility plant got the perfect finishing touch last week: an energy-saving roof filled with green, growing plants.
The garden topping the electrical room of the South Plant is a "green roof." These roofs use vegetation -- grasses, flowers and shrubs -- to create an additional insulating layer to help keep buildings cool. More than just dirt and plants placed on top of a building’s roof, green roofs are part of a building’s total roofing system. Properly designed, the “system” includes the roof structure, a waterproofing membrane, a specially designed drainage system, a growing medium (soil) and plantings. The plantings form the foundation of a rooftop ecosystem, supporting songbirds and other native animals and insects.
By protecting the building from direct sunlight, vegetated roofs protect the roof’s surface from the sun’s harmful ultraviolet rays, which can otherwise shorten the life of the roofing materials. The vegetation also limits damage from hailstorms, and during rain events, the soils that make up the roof will decrease the amount and rate of runoff, which helps reduce flooding.
Rice is planting three other vegetated green roofs -- one at Duncan College, at the Collaborative Research Center and at the Oshman Engineering Design Kitchen.
Green roofs today vary from simple utilitarian grass roofs to elaborate flowering rooftop parks, and Rice is experimenting with different species of plantings to determine which perform the best in a rooftop environment. The lessons learned here will help others in the Houston area identify the optimal plantings for their vegetated roofs, which is another way that Rice is seeking to improve the community around it.
“My hope is that 10 years from now, as someone flies over Houston in an airplane, or as birds fly across our sky, they’ll be able to look down and wonder where all the buildings went because all they see from their viewpoint is native landscape," said Richard Johnson, Rice's director of sustainability. "If vegetated green roofs cover our buildings, we’ll reduce our energy consumption, our flooding, and even the outdoor temperatures in summertime. At the same time, we will have helped to restore ecosystems disrupted by human development. This is a future that I think we can all get excited about helping to make possible.”