For a city that touts itself as a leader in green architecture, LA has few green roofs. Only recently, it got one of its first, designed by architect (and SCI-Arc professor) Alexis Rochas.
The sinuous project, located on top of The Flat, a new downtown residential building, is made of a folding and torqued galvanized sheet metal surface, prefabricated off site. This forms a series of platforms or “grow channels” filled with engineered soil that’s light enough not to weigh the project down. The tiered structure, supported by an armature of steel tubes and a plywood substructure, wraps around the building’s existing mechanical rooftop equipment, offering maximum solar exposure, maximum growing room, and efficient irrigation.
Besides filtering pollutants, increasing thermal insulation, and reducing storm water runoff, the 3,000-square-foot garden—engineered by Arup and built with the help of students at SCI-Arc—is its own ecosystem, with plants tended and used by residents and the chefs of The Flat’s ground-floor restaurant, Blue Velvet. Vegetation is then returned to the roof in the form of compost. Over 20 types of plants are grown here, rotated by season. This spring’s crop includes thyme, kale, artichokes, tomatoes, chard, Thai basil, four types of mint, and Walla Walla onions.
“It’s really an unexplored program,” said Rochas, noting that most green roofs are basically flat, and not necessarily architectural. He likens his design to a series of rolling hills. “Because it’s a mix of garden and sculpture, it’s something you can enjoy looking at, as well as using,” he said.
So is this the beginning of a green roof revolution in LA? Maybe not a revolution, but there are more planted roofs on the way. The city is putting a planted covering on its new Council District 9 constituent center in South LA, and a restroom in the new Vista Hermosa Park downtown has a green roof on top of it. According to the city’s Department of Environmental Affairs, the LA Zoo is also investigating a green roof for its upcoming reptile and insect center, and the city is considering installing a partial green roof above City Hall, although neither project has yet received funding.
To encourage more in the future, the Department of Environmental Affairs in 2007 published a Green Roof Resource Guide, laying out the best ways to create a green roof and get it through the regulatory process. Furthermore, the city’s new Green Building Ordinance, passed last fall, requires that new buildings pass a green checklist, and awards points for green roofs.
Still, Jill Sourial, environmental projects manager for City Councilman Ed Reyes (Sourial helped Rochas navigate the approvals process for his green roof), warns that the city won’t become the next Chicago, where green roofs are everywhere. Nor does she think that green roofs—which can be costly, and provide little storm water runoff benefits in a low-rain area like LA—will ever become mandatory. “It’s a good option for creating new open spaces, and for heat minimization, but in LA, it’s more for people who have a green aesthetic and want to promote that,” she said. City environmental supervisor
Jose Gutierrez is more upbeat, looking at green roofs’ citywide benefits, which could include an overall drop in air temperature, lower heating and cooling costs and less related emissions, new habitats for birds and insects, and a beautification of the city. “Would you rather look at concrete on the top of the building next to you, or a beautiful garden?” he asked.
(Additional photos and a video tour of the roof can be found here.)