One of the earliest green roofs on a commercial building in the U.S. was the Weyerhauser corporate headquarters in Federal Way, Washington, completed in 1971. The five-story reinforced concrete building features 134,218 square feet of its stepped overhangs sheathed in English ivy. The green roof was designed by landscape architect Peter Walker, of Sasaki Walker Associates.
Work Under Way
Two of the largest green roof projects under construction in the world are both atop water plants. The Victorian Desalination Plant in Wonthaggi, Australia, near Melbourne, will have a 26,000-sq-meter green roof with indigenous plants to camouflage the plant and provide corrosion resistance, thermal control and acoustic protection. It is expected to be completed next year, and will be the largest green roof in Australia.
The Croton Water Filtration Plant, taking shape in Bronx County in New York City, is sited on a golf course. As compensation, the plant roof will support a 36,512-sq-m golf driving range, which is expected to open in 2014.
Green roofs are now seen as having a positive impact on property values. "Green roofs increase energy savings. They positively impact the building itself as an amenity for the residents, and the buildings around ones with green roofs get the 'park effect,'" comments Somerville. "Looking at a green roof allows the neighboring building owners to command greater rents."
Politically, green roofs have gained support. "We're at the point now that it's a major part of the dialogue with public officials," Somerville adds. "Landscape architects are no longer having to put the value proposition out there. There's nothing but growth in the future of green roofs."
Visit our ">slideshow, where ENR rounds up the 10 largest green roofs in the world by square footage.