The site of the Horticulture and Landscape Architecture Display Garden, just east of the Lighty and French Administrative buildings on Washington State University’s Pullman campus, continues to be a hot spot of innovation. The latest development on the site of the old greenhouses is an equipment storage building sporting a “green” roof.
Green roofs serve several purposes for a building, such as absorbing rainwater, providing insulation, creating habitat for wildlife, and helping to lower urban air temperatures and combat heat island effects caused by building materials that retain heat.
Phil Waite, associate professor of landscape architecture, explained the two basic types of green roofs. Intensive roofs have a thick layer of soil that, while supporting a large variety of plants, require extra structural support in the buildings they cover. Extensive roofs have a thinner layer of soil and support a smaller selection of plants, but have largely the same benefits. Waite said that extensive green roofs are the wave of the future because they are easier and cheaper to implement than intensive ones.
The green roof in WSU’s display garden that is covered with sedums and dryland grasses is the first extensive green roof on the Pullman campus, said Waite. The garden, designed and built by students under Waite’s supervision, is intended to present a reproducible model of sustainability for gardening and building in the Palouse climate.
“Green roofs slow runoff,” said Waite. “The rainwater is captured and reused. The soil and plant material on the roof actually protect the roofing materials, extending the life of the roof by as much as 50 years. And heat gain is reduced by up to 20 percent. In an urban setting, green roofs reduce the effects of heat islands.”
Portland, Oregon, is a nexus of green roof projects, Waite said. “We took the students there to show them examples of good design. Then they came back to [the Pullman] campus and designed and built the equipment building and its green roof.”
Next time you’re on campus for a game or a reunion, stop by the garden and relax for a while. The benches, raised garden beds and pathways are all constructed with recycled materials from the old greenhouses and other campus projects further adding to the sustainable nature of the display garden.
– By Brian Clark
For a video tour of the garden, check out http://bit.ly/ad2ZBO.
Learn more about the display garden at http://horticulture.wsu.edu/display-garden/.