When Matthew Passmore, John Bela and Blaine Merker founded their design collective, Rebar, five years ago, they did so with the intention of melding landscape and urban design with art and activism and the goal of changing San Franciscans’ relationship with the physical space they call home.

For one of their first projects, Park(ing), Rebar turned one parking space into a temporary public park. Park(ing) Day has since gone global, with 140 cities and 21 countries participating on a single day (this year, Sept. 17). Rebar was also responsible for the 2008 Victory Garden in Civic Center, created in conjunction with Slow Food Nation. “Essentially 25 percent of the city’s land area is taken up by roadways,” says Passmore. “Our goal is to playfully provide different examples of how public space can be used.”

“We’ve provided the physical space for a new kind of imagination.”

In late 2009 they opened a design studio in the Mission, and earlier this year the trio spoke at the “Smart City” conference in Paris, bringing with them the Bushwaffle—an inflatable public lounge installation that transforms hard surfaces into soft playgrounds. Then there’s the Global Tacoshed project, which started as a meal at an SF taco truck and turned into a research assignment: CCA students mapped the origin of each ingredient in a taco in an effort to understand the complexities of both local and global food systems.

Rebar’s latest endeavors include their involvement in the citywide Pavement to Parks program. The team is creating sidewalk extensions in the form of mobile parklets that will debut on 22nd Street this summer. The group is also involved in the newly established Hayes Valley Farm, and will provide public artwork to aid in the revitalization of Leland Avenue in Visitacion Valley and Hilltop Park in Hunters Point. Rebar’s first retrospective will take place at the SF Planning and Urban Research Association this fall. “I’d say we had our finger on an emerging zeitgeist,” says Merker.