National Weather Center Green Roof

Vegetative roof systems, also known as green roofs, have been shown to improve energy and water efficiency and enhance water quality. The systems intercept solar radiation and cool structures during the summer months. Annual storm-water runoff also is reduced, and pollutants are reduced in the storm-water effluent.

“We are pleased to have the green roof at our complex,” said John Snow, College of Atmospheric and Geographic Sciences dean and administrator of the NWC. “The project is a combination of efforts between our School of Meteorology and the College of Architecture. It will provide opportunities and benefits not only to the two colleges through research, but also to the entire state of Oklahoma by offering insight into energy efficiency and water quality.”

The green roof, located on the National Weather Center’s sixth-floor outdoor classroom, comprises 1,280 square feet and consists of 160 planted green roof trays. The trays contain an engineered substrate consisting of lightweight sand, expanded clay and organic material. The substrate weighs about a third of the weight of regular topsoil. The roof is planted with sedums – exotic succulents that are highly adaptive to a green roof’s growing conditions. As part of the experiment, native dry-land prairie grasses and flowers will be seeded over the sedum for comparison.

Primary investigation areas for the green roof will include plant performance, changes in the radiation balance, cooling efficiency for various climate conditions and impacts on building day lighting. A second phase of the project is scheduled to begin later this year and will add an additional 220 square feet to the existing green roof. The roof will remain at the NWC for up to three years for investigation. Based on the research gathered, it will then be moved to a permanent location.

The green roof project is being led by Coffman, Petra Klein, OU School of Meteorology associate professor, and Lee Fithian, Division of Architecture assistant professor. The Oklahoma Water Resource Board and the Oklahoma Conservation Commission are the project sponsors.

“This green roof system will reduce storm water runoff quantity and improve discharge quality while reducing warm season energy demand loads,” said Reid Coffman, principal investigator for the NWC Experimental Green Roof project and Division of Landscape Architecture assistant professor. “This roof will be the subject of advanced examination into the water and energy performance of vegetative roof systems as contributors toward green urban development. By establishing this experimental project at OU, we hope to become one of the leaders in the state in the area of green-roof research, development and application. This will make Oklahoma more competitive for urban development, cost of living and overall quality of life."